Edge adapter architecture apparatus and method

An architecture for intercepting and processing packets from a network is disclosed. The architecture provides both stateful and stateless processing of packets in the bi-directional network flow. Further, stateless processing is provided by a parallel arrangement of network processors while stateful processing is provided by a serial arrangement of network processors. The architecture permits leveraging existing bi-directional devices to process packets in a uni-directional flow, thereby increasing the throughput of the device. The ability to share state among the stateless processor, among the stateful processors of each packet flow direction and between the stateless and stateful processors provides for dynamic adaptability and analysis of both historical and bi-directional packet activity.

BACKGROUND

The Internet is growing by leaps and bounds. Everyday, more and more users log on to the Internet for the first time and these, and existing users are finding more and more content being made available to them. The Internet has become a universal medium for communications, commerce and information gathering.

Unfortunately, the growing user base along with the growing content provider base is causing ever increasing congestion and strain on the Internet infrastructure, the network hardware and software plus the communications links that link it all together. While the acronym “WWW” is defined as “World Wide Web”, many users of the Internet have come to refer to it as the “World Wide Wait.”

These problems are not limited to the Internet either. Many companies provide internal networks, known as intranets, which are essentially private Internets for use by their employees. These intranets can become overloaded as well. Especially, when a company's intranet also provides connectivity to the Internet. In this situation, the intranet is not only carrying internally generated traffic but also Internet traffic generated by the employees.

The growth of the Internet has also resulted in more and more malicious programmer activity. These “hackers” spread virus programs or attempt to hack into Web sites in order to steal valuable information such as credit card numbers. Further, there have been an increasing number of “Denial of Service” attacks where a hacker infiltrates multiple innocent computers connected to the Internet and coordinates them, without their owners' knowledge, to bombard a particular Web site with an immense volume of traffic. This flood of traffic overwhelms the target's servers and literally shuts the Web site down.

Accordingly, there is a need for an enhanced Internet infrastructure to more efficiently deliver content from providers to users and provide additional network throughput, reliability, security and fault tolerance.

SUMMARY

The present invention is defined by the following claims, and nothing in this section should be taken as a limitation on those claims. By way of introduction, the preferred embodiments described below relate to an architecture for intercepting and processing packets transmitted from a source to a destination over a network. The architecture includes a packet interceptor coupled with the network and operative to selectively intercept the packets prior to receipt by the destination and at least one stateless processor coupled with the packet interceptor and operative to perform stateless processing tasks on the intercepted packets. The at least one stateless processor includes at least two stateless packet processors coupled in parallel, the processing of the intercepted packets being distributed among the at least two stateless packet processors. The architecture further includes at least one stateful processor coupled with the at least one stateless processor and operative to perform stateful processing tasks on the intercepted packets. The at least one stateful processor includes at least two stateful packet processors serially coupled with each other. Each of the at least two stateful packet processors is operative to perform a portion of the stateful processing tasks on the intercepted packets. The last of the two stateful packet processors being coupled with the network and operative to selectively release the intercepted packet back to the network.

The preferred embodiments further relate to a method of intercepting and processing packets transmitted from a source to a destination over a network. In one embodiment, the method includes intercepting, selectively, the packets prior to receipt by the destination, distributing the intercepted packets to at least two stateless packet processors operative to perform stateless processing tasks on the intercepted packets, performing the stateless processing task in parallel by the at least two stateless packet processors, receiving the intercepted packets from the at least two stateless packet processors by a first stateful packet processor operative to perform a first stateful packet processing task on the intercepted packets, receiving the intercepted packets from the first stateful packet processor by a second stateful packet processor operative to perform a second stateful processing task on the intercepted packets, and releasing, selectively, the intercepted packets.

Further aspects and advantages of the invention are discussed below in conjunction with the preferred embodiments.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIG. 1shows an exemplary network100for use with the presently preferred embodiments. It is preferred that the network100be a publicly accessible network, and in particular, the Internet. While, for the purposes of this disclosure, the disclosed embodiments will be described in relation to the Internet, one of ordinary skill in the art will appreciate that the disclosed embodiments are not limited to the Internet and are applicable to other types of public networks as well as private networks, and combinations thereof, and all such networks are contemplated.

As an introduction, a network interconnects one or more computers so that they may communicate with one another, whether they are in the same room or building (such as a Local Area Network or LAN) or across the country from each other (such as a Wide Area Network or WAN). A network is a series of points or nodes126interconnected by communications paths128. Networks can interconnect with other networks and can contain sub-networks. A node126is a connection point, either a redistribution point or an end point, for data transmissions generated between the computers which are connected to the network. In general, a node126has a programmed or engineered capability to recognize and process or forward transmissions to other nodes126. The nodes126can be computer workstations, servers, bridges or other devices but typically, these nodes126are routers or switches.

A router is a device or, in some cases, software in a computer, that determines the next network node126to which a piece of data (also referred to as a “packet” in the Internet context) should be forwarded toward its destination. The router is connected to at least two networks or sub-networks and decides which way to send each information packet based on its current understanding of the state of the networks to which it is connected. A router is located at any juncture of two networks, sub-networks or gateways, including each Internet point-of-presence (described in more detail below). A router is often included as part of a network switch. A router typically creates or maintains a table of the available routes and their conditions and uses this information along with distance and cost algorithms to determine the best route for a given packet. Typically, a packet may travel through a number of network points, each containing additional routers, before arriving at its destination.

The communications paths128of a network100, such as the Internet, can be coaxial cable, fiber optic cable, telephone cable, leased telephone lines such as T1 lines, satellite links, microwave links or other communications technology as is known in the art. The hardware and software which allows the network to function is known as the “infrastructure.” A network100can also be characterized by the type of data it carries (voice, data, or both) or by the network protocol used to facilitate communications over the network's100physical infrastructure.

The Internet, in particular, is a publicly accessible worldwide network100which primarily uses the Transport Control Protocol and Internet Protocol (“TCP/IP”) to permit the exchange of information. At a higher level, the Internet supports several applications protocols including the Hypertext Transfer Protocol (“HTTP”) for facilitating the exchange of HTML/World Wide Web (“WWW”) content, File Transfer Protocol (“FTP”) for the exchange of data files, electronic mail exchange protocols, Telnet for remote computer access and Usenet (“NNTP” or Network News Transfer Protocol) for the collaborative sharing and distribution of information. It will be appreciated that the disclosed embodiments are applicable to many different applications protocols both now and later developed.

Logically, the Internet can be thought of as a web of intermediate network nodes126and communications paths128interconnecting those network nodes126which provide multiple data transmission routes from any given point to any other given point on the network100(i.e. between any two computers connected to the network100). Physically, the Internet can also be thought of as a collection of interconnected sub-networks wherein each sub-network contains a portion of the intermediate network nodes126and communications paths128. The division of the Internet into sub-networks is typically geographically based, but can also be based on other factors such as resource limitations and resource demands. For example, a particular city may be serviced by one or more Internet sub-networks provided and maintained by competing Internet Service Providers (“ISPs”) (discussed in more detail below) to support the service and bandwidth demands of the residents.

Contrasting the Internet with an intranet, an intranet is a private network contained within an enterprise, such as a corporation, which uses the TCP/IP and other Internet protocols, such as the World Wide Web, to facilitate communications and enhance the business concern. An intranet may contain its own Domain Name Server (“DNS”) and may be connected to the Internet via a gateway, i.e., an intra-network connection, or gateway in combination with a proxy server or firewall, as are known in the art.

Referring back toFIG. 1, clients102,104,106and servers108,110,112are shown coupled with the network100. Herein, the phrase “coupled with” is defined to mean directly connected to or indirectly connected with, through one or more intermediate components. Such intermediate components may include both hardware and software based components. The network100facilitates communications and interaction between one or more of the clients102,104,106and one or more of the servers108,110,112(described in more detail below). Alternatively, the network100also facilitates communications and interaction among one or more of the clients102,104,106, e.g. between one client102,104,106and another client102,104,106or among one or more of the servers108,110,112, e.g. between one server108,110,112and another server108,110,112.

A client102,104,106may include a personal computer workstation, mobile or otherwise, wireless device such as a personal digital assistant or cellular telephone, an enterprise scale computing platform such as a mainframe computer or server or may include an entire intranet or other private network which is coupled with the network100. Typically, a client102,104,106initiates data interchanges with other computers, such as servers108,110,112coupled with the network100. These data interchanges most often involve the client requesting data or content from the other computer and the other computer providing that data or content in response to the request. Alternatively, the other computer coupled with the network can “push” data or content to the client102,104,106without it first being requested. For example, an electronic mail server108,110,112may automatically push newly received electronic mail over the network100to the client102,104,106as the new electronic mail arrives, alleviating the client102,104,106from first requesting that new mail be sent. It will be apparent to one of ordinary skill in the art that there can be many clients102,104,106coupled with the network100.

A server108,110,112may include a personal computer workstation, an enterprise scale computing platform or other computer system as are known in the art. A server108,110,112typically responds to requests from clients102,104,106over the network100. In response to the request, the server108,110,112provides the requested data or content to the client102,104,106which may or may not require some sort of processing by the server108,110,112or another computer to produce the requested response. It will be apparent to one of ordinary skill in the art that a client102,104,106may also be a server108,110,112and vice versa depending upon the nature of the data interchange taking place, e.g. peer-to-peer architectures. For purposes of this disclosure, during any given communication exchange, a client102,104,106requests or receives content and is separate from the server108,110,112which provides the content (whether requested or not, i.e. pushed). Preferably, servers108,110,112are World Wide Web servers serving Web pages and/or Web content to the clients102,104,106(described in more detail below). It will be apparent to one of ordinary skill in the art that there can be many servers108,110,112coupled with the network100.

Clients102,104,106are each coupled with the network100at a point of presence (“POP”)114,116. The POP114,116is the connecting point which separates the client102,104,106from the network100. In a public network100, such as the Internet, the POP114,116is the logical (and possibly physical) point where the public network100ends, after which comes the private (leased or owned) hardware or private (leased or owned) network of the client102,104,106. A POP114,116is typically provided by a service provider118,120, such as an Internet Service Provider (“ISP”)118,120, which provides connectivity to the network100on a fee for service basis. A POP114,116may actually reside in rented space owned by telecommunications carrier such as AT&T or Sprint to which the ISP118,120is connected. A POP114,116may be coupled with routers, digital/analog call aggregators, servers108,110,112, and frequently frame relay or ATM switches. As will be discussed below, a POP114,116may also contain cache servers and other content delivery devices.

A typical ISP118,120may provide multiple POP's114,116to simultaneously support many different clients102,104,106connecting with the network100at any given time. A POP114,116is typically implemented as a piece of hardware such as a modem or router but may also include software and/or other hardware such as computer hardware to couple the client102,104,106with the network100both physically/electrically and logically (as will be discussed below). The client102,104,106connects to the POP114,116over a telephone line or other transient or dedicated connection. For example, where a client102,104,106is a personal computer workstation with a modem, the ISP118,120provides a modem as the POP114,116to which the client102,104,106can dial in and connect to via a standard telephone line. Where the client102,104,106is a private intranet, the POP114,116may include a gateway router which is connected to an internal gateway router within the client102,104,106by a high speed dedicated communication link such as T1 line or a fiber optic cable.

A service provider118,120will generally provide POP's114,116which are geographically proximate to the clients102,104,106being serviced. For dial up clients102,104,106, this means that the telephone calls can be local calls. For any client102,104,106, a POP which is geographically proximate typically results in a faster and more reliable connection with the network100. Servers108,110,112are also connected to the network100by POP's114,116. These POP's114,116typically provide a dedicated, higher capacity and more reliable connection to facilitate the data transfer and availability needs of the server108,110,112. Where a client102,104,106is a wireless device, the service provider118,120may provide many geographically dispersed POP's114,116to facilitate connecting with the network100from wherever the client102,104,106may roam or alternatively have agreements with other service providers118,120to allow access by each other's customers. Each service provider118,120, along with its POP's114,116and the clients102,104,106effectively forms a sub-network of the network100.

Note that there may be other service providers118,120“upstream” which provide network100connectivity to the service providers118,120which provide the POP's114,116. Each upstream service provider118,120along with its downstream service providers118,120again forms a sub-network of the network100. Peering is the term used to describe the arrangement of traffic exchange between Internet service providers (ISPs)118,120. Generally, peering is the agreement to interconnect and exchange routing information. More specifically, larger ISP's118,120with their own backbone networks (high speed, high capacity network connections which interconnect sub-networks located in disparate geographic regions) agree to allow traffic from other large ISP's118,120in exchange for traffic on their backbones. They also exchange traffic with smaller service providers118,120so that they can reach regional end points where the POP's114,116are located. Essentially, this is how a number of individual sub-network owners compose the Internet. To do this, network owners and service providers118,120, work out agreements to carry each other's network traffic. Peering requires the exchange and updating of router information between the peered ISP's118,120, typically using the Border Gateway Protocol (BGP). Peering parties interconnect at network focal points such as the network access points (NAPs) in the United States and at regional switching points. Private peering is peering between parties that are bypassing part of the publicly accessible backbone network through which most Internet traffic passes. In a regional area, some service providers118,120have local peering arrangements instead of, or in addition to, peering with a backbone service provider118,120.

A network access point (NAP) is one of several major Internet interconnection points that serve to tie all of the service providers118,120together so that, for example, an AT&T user in Portland, Oreg. can reach the Web site of a Bell South customer in Miami, Fla. The NAPs provide major switching facilities that serve the public in general. Service providers118,120apply to use the NAP facilities and make their own inter-company peering arrangements. Much Internet traffic is handled without involving NAPs, using peering arrangements and interconnections within geographic regions.

For purposes of later discussions, the network100can be further logically described to comprise a core122and an edge124. The core122of the network100includes the servers108,110,112and the bulk of the network100infrastructure, as described above, including larger upstream service providers118,120, and backbone communications links, etc. Effectively, the core122includes everything within the network100up to the POP's114,116. The POP's114,116and their associated hardware lie at the edge124of the network100. The edge124of the network100is the point where clients102,104,106, whether single devices, computer workstations or entire corporate internal networks, couple with the network100. As defined herein, the edge124of the network100may include additional hardware and software such as Domain Name Servers, cache servers, proxy servers and reverse proxy servers as will be described in more detail below. Typically, as the network100spreads out from the core122to the edge124, the total available bandwidth of the network100is diluted over more and more lower cost and lower bandwidth communications paths. At the core122, bandwidth over the higher capacity backbone interconnections tends to be more costly than bandwidth at the edge124of the network100. As with all economies of scale, high bandwidth interconnections are more difficult to implement and therefore rarer and more expensive than low bandwidth connections. It will be appreciated, that even as technology progresses, newer and higher bandwidth technologies will remain more costly than lower bandwidth technologies.

II. The World Wide Web

As was discussed above, clients102,104,106engage in data interchanges with servers108,110,112. On the Internet, these data exchanges typically involve the World Wide Web (“WWW”). Relative to the TCP/IP suite of protocols (which are the basis for information exchange on the Internet), HTTP is an application protocol. A technical definition of the World Wide Web is all the resources and users on the Internet that are using the Hypertext Transfer Protocol (“HTTP”). HTTP is the set of rules for exchanging data in the form of files (text, graphic images, audio, video, and other multimedia files, such as streaming media and instant messaging), also known as Web content, between clients102,104,106and servers108,110,112. Servers108,110,112which serve Web content are also known as Web servers108,110,112.

Essential concepts that are part of HTTP include (as its name implies) the idea that files/content can contain references to other files/content whose selection will elicit additional transfer requests. Any Web server108,110,112contains, in addition to the files it can serve, an HTTP daemon, a program that is designed to wait for HTTP requests and handle them when they arrive. A personal computer Web browser program, such as Microsoft™ Internet Explorer, is an HTTP client program (a program which runs on the client102,104,106), sending requests to Web servers108,110,112. When the browser user enters file requests by either “opening” a Web file (typing in a Uniform Resource Locator or URL) or clicking on a hypertext link, the browser builds an HTTP request and sends it to the Web server108,110,112indicated by the URL. The HTTP daemon in the destination server108,110,112receives the request and, after any necessary processing, returns the requested file to the client102,104,106.

The Web content which a Web server typically serves is in the form of Web pages which consist primarily of Hypertext Markup Language. Hypertext Markup Language (“HTML”) is the set of “markup” symbols or codes inserted in a file usually containing text intended for display on a World Wide Web browser. The markup tells the Web browser how to display a Web page's content for the user. The individual markup codes are referred to as elements or tags. Web pages can further include references to other files which are stored separately from the HTML code, such as image or other multimedia files to be presented in conjunction with the text Web content.

A Web site is a related collection of Web files/pages that includes a beginning HTML file called a home page. A company or an individual tells someone how to get to their Web site by giving that person the address or domain name of their home page (the addressing scheme of the Internet and the TCP/IP protocol is described in more detail below). From the home page, links are typically provided, either directly or through intermediate pages, to all the other pages (HTML files) located on their site. For example, the Web site for IBM™ has the home page address of http://www.ibm.com. Alternatively, the home page address may include a specific file name like index.html but, as in IBM's case, when a standard default name is set up, users don't have to enter the file name. IBM's home page address leads to thousands of pages, but a Web site may also consist of just a few pages.

Since site implies a geographic place, a Web site can be confused with a Web server108,110,112. As was discussed above, a server108,110,112is a computer that holds and serves the HTML files, images and other data for one or more Web sites. A very large Web site may be spread over a number of servers108,110,112in different geographic locations or one server108,110,112may support many Web sites. For example, a Web hosting company may provide server108,110,112facilities to a number of Web sites for a fee. Web sites can also contain links to pages or files on other Web sites.

III The Domain Name System

As was described above, the network100facilitates communications between clients102,104,106and servers108,110,112. More specifically, the network100facilitates the transmission of HTTP requests from a client102,104,106to a server108,110,112and the transmission of the server's108,110,112, response to that request, the requested content, back to the client102,104,106. In order to accomplish this, each device coupled with the network100, whether it be a client102,104,106or a server108,110,112must provide a unique identifier so that communications can be routed to the correct destination. On the Internet, these unique identifiers comprise domain names (which generally will include World Wide Web Uniform Resource Locators or “URL's”) and Internet Protocol addresses or “IP” addresses. Every client102,104,106and every server108,110,112must have a unique IP address so that the network100can reliably route communications to it. Additionally, clients102,104,106and servers108,110,112can be coupled with proxy servers (forward, reverse or transparent), discussed in more detail below, which allow multiple clients102,104,106or multiple servers108,110,112to be associated with a single domain name or a single IP address. In addition, a particular server108,110,112may be associated with multiple domain names and/or IP addresses for more efficient handling of requests or to handle multiple content providers, e.g. multiple Web sites, on the same server108,110,112. Further, as was discussed above, since a POP114,116provides the connecting point for any particular client102,104,106to connect to the network100, it is often satisfactory to provide each POP114,116with a single unique domain name and IP address since the POP114,116will reliably deliver any communications received by it to its connected client102,104,106. Where the client102,104,106is a private network, it may have its own internal hardware, software and addressing scheme (which may also include domain names and IP addresses) to reliably deliver data received from the POP114,116to the ultimate destination within the private network client102,104,106.

As was discussed, the Internet is a collection of interconnected sub-networks whose users communicate with each other. Each communication carries the address of the source and destination sub-networks and the particular machine within the sub-network associated with the user or host computer at each end. This address is called the IP address (Internet Protocol address). In the current implementation of the Internet, the IP address is a 32 bit binary number divided into four 8 bit octets. This 32-bit IP address has two parts: one part identifies the source or destination sub-network (with the network number) and the other part identifies the specific machine or host within the source or destination sub-network (with the host number). An organization can use some of the bits in the machine or host part of the address to identify a specific sub-network within the sub-network. Effectively, the IP address then contains three parts: the sub-network number, an additional sub-network number, and the machine number.

One problem with IP addresses is that they have very little meaning to ordinary users/human beings. In order to provide an easier to use, more user friendly network100, a symbolic addressing scheme operates in parallel with the IP addressing scheme. Under this symbolic addressing scheme, each client102,104,106and server108,110,112is also given a “domain name” and further, individual resources, content or data are given a Uniform Resource Locator (“URL”) based on the domain name of the server108,110,112on which it is stored. Domain names and URL's are human comprehensible text and/or numeric strings which have symbolic meaning to the user. For example, a company may have a domain name for its servers108,110,112which is the company name, i.e., IBM Corporation's domain name is ibm.com. The portion of the domain name immediately following the period or “dot” is used to identify the type of organization to which the domain name belongs. These are called “top-level” domain names and include com, edu, org, mil, gov, etc. Com indicates a corporate entity, edu indicates an educational institution, mil indicates a military entity, and gov indicates a government a entity. It will be apparent to one of ordinary skill in the art that the text strings which make up domain names may be arbitrary and that they are designed to have relevant symbolic meaning to the users of the network100. A URL typically includes the domain name of the provider of the identified resource, an indicator of the type of resource and an identifier of the resource itself. For example, for the URL “http://www.ibm.com/index.html”, http identifies this resource as a hypertext transfer protocol compatible resource, www.ibm.com is the domain name (again, the www is arbitrary and typically is added to indicate to a user that the server108,110,112, associated with this domain name is a world wide Web server), and index.html identifies a hypertext markup language file named “index.html” which is stored on the identified server108,110,112.

Domain names make the network100easier for human beings to utilize it, however the network infrastructure ultimately uses IP addresses, and not domain names, to route data to the correct destination. Therefore, a translation system is provided by the network100to translate the symbolic human comprehensible domain names into IP addresses which can then be used to route the communications. The Domain Name System (“DNS”) is the way that Internet domain names are located and translated into IP addresses. The DNS is a distributed translation system of address translators whose primary function is to translate domain names into IP addresses and vice versa. Due to the ever expanding number of potential clients102,104,106and servers108,110,112coupled with the network100(currently numbering in the millions), maintaining a single central list of domain name/IP address correspondences would be impractical. Therefore, the lists of domain names and corresponding IP addresses are distributed throughout the Internet in a hierarchy of authority. A DNS server, typically located within close geographic proximity to a service provider118,120(and likely provided by that service provider118,120), handles requests to translate the domain names serviced by that service provider118,120or forwards those requests to other DNS servers coupled with the Internet for translation.

DNS translations (also known as “lookups” or “resolutions”) can be forward or reverse. Forward DNS translation uses an Internet domain name to find an IP address. Reverse DNS translation uses an Internet IP address to find a domain name. When a user enters the address or URL for a Web site or other resource into their browser program, the address is transmitted to a nearby router which does a forward DNS translation in a routing table to locate the IP address. Forward DNS translations are the more common translation since most users think in terms of domain names rather than IP addresses. However, occasionally a user may see a Web page with a URL in which the domain name part is expressed as an IP address (sometimes called a dot address) and wants to be able to see its domain name, to for example, attempt to figure the identity of who is providing the particular resource. To accomplish this, the user would perform a reverse DNS translation.

The DNS translation servers provided on the Internet form a hierarchy through which any domain name can be “resolved” into an IP address. If a particular DNS translation server does not “know” the corresponding IP address of a given domain name, it “knows” other DNS translation servers it can “ask” to get that translation. This hierarchy includes “top-level” DNS translation servers which “know” which resources (clients102,104,106or servers108,110,112) have a particular top level domain identifier, i.e. com, gov, edu, etc. as described above. This hierarchy further continues all the way up to the actual resource (client102,104,106or server108,110,112) which is typically affiliated with a DNS translation server which “knows” about it and its IP address. A particular DNS translation server “knows” of a translation when it exists in its table of translations and has not expired. Any particular translation will typically be associated with a Time to Live (“TTL”) which specifies a duration, time or date after which the translation expires. As discussed, for a given translation, if a DNS translation server does not know the translation, because it is not in its routing table or it has expired, that DNS translation server will have to inquire up the hierarchical chain of DNS translation servers in order to make the translation. In this way, new domain name and IP address translations can be propagated through the DNS translation server hierarchy as new resources are added and old resources are assigned new addresses.

Referring now toFIG. 2, there is shown a diagram illustrating the basic operation of the Domain Name System200. Depicted in the figure are clients102,104,106, labeled “Client1”, “Client2” and “Client3.” Clients1and2are coupled with POP's114provided by service provider120, labeled “POP1A” and “POP1B.” Client3is coupled with a POP (not shown) provided by service provider118, labeled “POP2.” In addition, service providers118,120may provide additional POP's114for other clients102,104,106as described above. Service provider120is shown further coupled with service provider118, a server108, labeled “Server1”, preferably a Web server and more preferably an entire Web site which may comprise multiple sub-servers (not shown) as discussed above, and a top-level DNS translation server202, labeled “DNS Top”, all via the network100which is preferably the Internet. Furthermore, service provider120further includes a DNS translation server204, labeled “DNS A” and routing and interconnection hardware206, as described above, to electrically and logically couple the POP's114with the network100. Optionally, the service provider120may also include a cache server208or proxy server (not shown) to enhance content delivery as described below.

In order for a client102,104,106to generate a request for content to a particular server108, the client102,104,106first determines the IP address of the server108so that it can properly address its request. Referring to Client1102, an exemplary DNS translation transaction where the client102,104,106is a single workstation computer is depicted. A user of Client1enters a URL or domain name of the Server1108and specific resource contained within Server1, such as a sub-server, into their browser program in order to make a request for content. The browser program typically handles negotiating the DNS translation transaction and typically has been pre-programmed (“bound”) with the IP address of a particular DNS translation server to go to first in order to translate a given domain name. Typically, this bound DNS translation server will be DNS A204provided by the service provider120. Alternatively, where the client102,104,106is not bound to a particular DNS translation server, the service provider120can automatically route translation requests received by its POP's114to its DNS translation server, DNS A202. The process by which a domain name is translated is often referred to as the “slow start” DNS translation protocol. This is in contrast to what is known as the “slow start HTTP” protocol which will be discussed below in more detail in relation to content delivery.

Client1102then sends its translation request, labeled as “A1”, to its POP114, POP1A. The request, A1, is addressed with a return address of Client1and with the IP address of the bound DNS A204therefore the service provider's120routing equipment206automatically routes the request to DNS A204, labeled as “B.” Assuming DNS A204does not know how to translate the given domain name in the request or the translation in its routing table has expired, it must go up the DNS hierarchy to complete the translation. DNS A204will then forward a request, labeled “C”, upstream to the top-level DNS translation server202associated with the top-level domain in the domain address, i.e. com, gov, edu etc. DNS A204has been pre-programmed with the IP addresses of the various hierarchical servers that it may need to talk to in order to complete a translation. DNS A204addresses request C with the IP address of the top-level DNS server202and also includes its own return address. DNA then transmits the request over the network100which routes the request to the top level DNS server202. The top-level DNS server202will then translate and return the IP address corresponding to Server1108back to DNS A204via the network100, labeled “D.”

As was discussed above, a particular domain name may be associated with multiple IP addresses of multiple sub-servers108,110,112, as in the case of a Web site which, due to its size, must be stored across multiple sub-servers108,110,112. Therefore, in order to identify the exact sub-server which can satisfy the request of the Client1102, DNS A204must further translate the domain address into the specific sub-server108. In order to accomplish this, Server1108provides its own DNS translation server210which knows about the various sub-servers and other resources contained within Server1108. DNS A204, now knowing the IP address of Server1108, e.g. the Web site generally, can create a request, labeled “E”, to translate the domain name/URL provided by Client1102into the exact sub-server/resource on Server1108. DNS B210returns the translation, labeled “F”, to DNS A204which then returns it to Client1102via the service provider's routing equipment206, labeled “G”, which routes the response through POP1A114to the Client1, labeled “H1.” Client1102now has the IP address it needs to formulate its content requests to Server1108.

FIG. 2, further depicts an exemplary DNS translation transaction wherein the client102,104,106is a private network such as an intranet. For example, client2104may comprise its own network of computer systems. Further more, client2104may provide its own DNS translation server (not shown) to handle internal routing of data as well as the routing of data over the network100generally for the computer systems coupled with this private network. In this case, the internal DNS translation server will either be programmed to send its unknown translations to DNS A (labeled as “A2”, “B”, “C”, “D”, “E”, “F”, “G”, “H2”) or may be programmed to use the DNS hierarchy itself, i.e. communicate directly with the upstream DNS Top202and DNS B210(labeled as “A2”, “B2”, “C2”, “D2”, “E2”, “F2”, “G2”, “H2”). In these cases, the internal DNS translation server simply adds another layer to the DNS hierarchy as a whole, but the system continues to function similarly as described above.

In addition,FIG. 2, further depicts an exemplary DNS translation transaction wherein the client102,104,106is coupled with a POP114that is not associated with its bound DNS translation server204. For example, Client3106is depicted as being coupled with POP2provided by service provider118. In the exemplary situation, Client3106is bound with DNS A204provided by service provider120. This situation can occur in the wireless environment, where a particular wireless client102,104,106couples with whatever POP114,116is available in its geographic proximity (e.g. when roaming) and is affiliated, e.g. has access sharing agreements, with the service provider120who generally provides connectivity services for the client102,104,106. In this case, client3106will perform its translation requests as described above, and will address these requests to its bound DNS Server, in this case DNS A204. The service provider118will see the address of the DNS A204in client3's106translation requests and appropriately route the translation request over the network100to service provider120and ultimately on to DNS A204. DNS A204will appropriately handle the request and return it via the network100accordingly (labeled as “A3”, “B”, “C”, “D”, “E”, “F”, “G”, “H3”).

It will be appreciated that in each of the examples given above, if a particular DNS translation server already “knows” the requested translation, the DNS translation server does not have to go up the hierarchy and can immediately return the translation to the requester, either the client102,104,106or downstream DNS translation server.

It should be noted, that because a given server108,110,112may comprise multiple IP addresses, the DNS translation servers may be programmed to return a list of IP addresses in response to a given domain name translation request. Typically, this list will be ordered from the most optimal IP address to the least optimal IP address. The browser program can then pick one of the IP addresses to send content requests to and automatically switch to another IP address should the first requests fail to reach the destination server108,110,112due to a hardware failure or network100congestion. It will further be appreciated that the operations and structure of the existing DNS system are known to those of ordinary skill in the art.

IV. Content Delivery

As mentioned above, once the DNS translation is complete, the client102,104,106can initiate its requests for content from the server108. Typically, the requests for content will be in the form of HTTP requests for Web content as described above. In order to alleviate server108overload, the HTTP protocol provides a “slow start” mechanism. As was described above, a Web page consists of HTML code plus images, multimedia or other separately stored content. Typically, the amount of HTML code contained within a Web page is very small compared to the amount of image and/or multimedia data. When a client requests a Web page from the server108, the server108must serve the HTML code and the associated image/multimedia data to the client102,104,106. However, the client102,104,106, upon receipt of the HTML code, may be unwilling or unable, for whatever reason, to receive the associated image/multimedia data. To prevent the server108from wasting processing and bandwidth resources unnecessarily by sending unwanted data, the HTTP slow start protocol forces the client102,104,106to first request the HTML code and then subsequent to receipt of that HTML code, request any associated separately stored content. In this way, if after the initial request, the client102,104,106disconnects or otherwise switches to making requests of another server108, the initial server108is not burdened with serving the unwanted or unnecessary content.

In addition, it important to note that clients102,104,106may be located very far from each other, either geographically or even logically in consideration of the network topology. For example, a client102,104,106may be located in Chicago, Ill. while the server108from which it is requesting content is located in Paris, France. Alternatively, client102,104,106may be located in the same city as server108but, due to the topology of the network100, there may be multiple nodes126and interconnecting communications paths128between the client102,104,106and the server108necessitating a lengthy route for any data transmitted between the two. Either scenario can significantly impact the response time of a server108to a given request from a client102,104,106. Adding in the fact that the network100may be servicing millions of clients102,104,106and servers108at any given time, the response time may be further impacted by reduced bandwidth and capacity caused by network congestion at the server108or at one or more intermediate network nodes126.

Servers108and service providers118,120may attempt to alleviate this problem by increasing the speed and bandwidth capacity of the network100interconnections. Further, servers108may attempt to alleviate slow request response times by providing multiple sub-servers which can handle the volume of requests received with minimal latency. These sub-servers can be provided behind a reverse proxy server which, as described above, is “tightly coupled” with the Web site and can route content requests directed to a single IP address, to any of the multiple sub-servers. This reduces the number of individual translations that have to be made available to the DNS translation system and kept up to date for all of the sub-servers. The reverse proxy server can also attempt to balance the load across multiple sub-servers by allocating incoming requests using, for example, a round-robin routine. Reverse proxy servers can further include a cache server as described below to further enhance the Server's108ability to handle a high volume of requests or the serving of large volumes of data in response to any given request. It will be appreciated that reverse proxy servers and load balancing techniques are generally known to those of ordinary skill in the art.

Clients102,104,106and service providers118,120(and, as described above, servers108) may attempt to alleviate this problem by including a cache or cache server208. A cache server208is a server computer (or alternatively implemented in software directly on the client102,104,106or another computer coupled with the client102,104,106such as at the POP114) located, both logically and geographically, relatively close to the client102,104,106. The cache server208saves/caches Web pages and other content that clients102,104,106, who share the cache server, have requested in the past. Successive requests for the same content can then be satisfied by the cache server208itself without the need to contact the source of the content. A cache server208reduces the latency of fulfilling requests and also reduces the load on the content source. Further, a cache server208at the edge124of the Internet reduces the consumption of bandwidth at the core122of the Internet where it is more expensive. The cache server208may be a part of a proxy server or may be provided by a service provider118,120.

Cache servers208invisibly intercept requests for content and attempt to provide the requested content from the cache (also known as a “hit”). Note that a cache server208is not necessarily invisible, especially when coupled with a proxy server. In this case, the client102,104,106may need to be specially programmed to communicate its content requests to the proxy server in order to utilize the cache server. Cache servers208, as referred to in this disclosure then, may include these visible cache servers as well as invisible cache servers which transparently intercept and attempt to service content requests. Where the requested content is not in the cache (also known as a “miss”), the cache forwards the request onto the content source. When the source responds to the request by sending the content to the client102,104,106, the cache server208saves a copy of the content in its cache for later requests. In the case where a cache server is part of a proxy server, the cache/proxy server makes the request to the source on behalf of the client102,104,106. The source then provides the content to the cache/proxy server which caches the content and also forwards the requested content to the client102,104,106. An exemplary software based cache server is provided by SQUID, a program that caches Web and other Internet content in a UNIX-based proxy server closer to the user than the content-originating site. SQUID is provided as open source software and can be used under the GNU license for free software, as is known in the art.

Caches operate on two principles, temporal locality and spatial locality. Temporal locality is a theory of cache operation which holds that data recently requested will most likely be requested again. This theory dictates that a cache should store only the most recent data that has been requested and older data can be eliminated from the cache. Spatial Locality is a theory of cache operation which holds that data located near requested data (e.g. logically or sequentially) will be likely to be requested next. This theory dictates that a cache should fetch and store data in and around the requested data in addition to the requested data. In practice, this means that when a HTML Web page is requested, the cache should go ahead and request the separately stored content, i.e. begin the slow start process because more likely than not, the client102,104,106will request this data upon receipt of the HTML code.

While cache servers208alleviate some of the problems with net congestion and request response times, they do not provide a total solution. In particular, they do not provide a viable solution for dynamic content (content which continually changes, such as news, as opposed to static or fixed content). This type of content cannot be cached otherwise the requesting client102,104,106will receive stale data. Furthermore, cache servers208often cannot support the bandwidth and processing requirements of streaming media, such as video or audio, and must defer these content requests to the server108which are the source of the content. Cache servers208, in general, further lack the capability to service a large volume of requests from a large volume of clients102,104,106due to the immense capacity requirements. Typically, then general cache servers208, such as those provided by a service provider118,120will have high miss rates and low hit rates. This translates into a minimal impact on server108load, request response times and network100bandwidth. Moreover, as will be discussed below, by simply passing on requests which miss in the cache to the server108to handle, the server108is further subjected to increased security risks from the untrusted network100traffic which may comprise, for example, a denial of service attack or an attempt by a hacker to gain unauthorized access.

Referring now toFIG. 3, there is depicted an enhanced content delivery system300which provides optimized caching of content from the server108to the client102,104,106utilizing the HTTP slow start protocol. The system300is typically provided as a pay-for service by a content delivery service to which particular servers108subscribe to in order to enhance requests made by clients102,104,106for their specific content.FIG. 3depicts the identical DNS system ofFIG. 2but adds cache servers302and304, labeled “Cache C1” and “Cache C2” plus a special DNS translation server306, labeled “DNS C” affiliated with the content delivery service.

The depicted system300implements one known method of “Content Delivery.” Content delivery is the service of copying the pages of a Web site to geographically dispersed cache servers302,304and, when a page is requested, dynamically identifying and serving the page from the closest cache server302,304to the requesting client102,104,106, enabling faster delivery. Typically, high-traffic Web site owners and service providers118,120subscribe to the services of the company that provides content delivery. A common content delivery approach involves the placement of cache servers302,304at major Internet access points around the world and the use of a special routing code embedded in the HTML Web pages that redirects a Web page request (technically, a Hypertext Transfer Protocol—HTTP—request) to the closest cache server302,304. When a client102,104,106requests the separately stored content of a Web site/server108that is “content-delivery enabled,” the content delivery network re-directs that client102,104,106to makes its request, not from the site's originating server108, but to a cache server302,304closer to the user. The cache server302,304determines what content in the request exists in the cache, serves that content to the requesting client102,104,106, and retrieves any non-cached content from the originating server108. Any new content is also cached locally. Other than faster loading times, the process is generally transparent to the user, except that the URL ultimately served back to the client102,104,106may be different than the one initially requested. Content delivery is similar to but more selective and dynamic than the simple copying or mirroring of a Web site to one or several geographically dispersed servers. It will further be appreciated that geographic dispersion of cache servers is generally known to those of ordinary skill in the art.

FIG. 3further details a known method of re-directing the requests generated by the client102,104,106to a nearby cache server302,304. This method utilizes the HTTP slow start protocol described above. When a client102,104,106wishes to request content from a particular server108, it will obtain the IP address of the server108, as described above, using the normal DNS translation system. Once the server's108IP address is obtained, the client102,104,106will make its first request for the HTML code file which comprises the desired Web page. As given by the HTTP slow start protocol, the server108will serve the HTML code file to the client102,104,106and then wait for the client102,104,106to request the separately stored files, e.g., the image and multimedia files, etc. Normally, these requests are made in the same way that the initial content request was made, by reading each URL from the HTML code file which identifies the separately stored content and formulating a request for that URL. If the domain name for the URL of the separately stored content is the same as the domain name for the initially received HTML code file, then no further translations are necessary and the client102,104,106can immediately formulate a request for that separately stored content because it already has the IP address. However, if the URL of the separately stored content comprises a different domain name, then the client102,104,106must go through the DNS translation process again to translate the new domain name into an IP address and then formulate its requests with the appropriate IP address. The exemplary content delivery service takes advantage of this HTTP slow start protocol characteristic.

The exemplary content delivery service partners with the subscribing Web server108and modifies the URL's of the separately stored content within the HTML code file for the particular Web page. The modified URL's include data which will direct their translation requests to a specific DNS translation server306, DNS C provided by the content delivery service. DNS C is an intelligent translation server which attempts to figure out where the client102,104,106is geographically located and translate the URL to point to a cache server302,304which is geographically proximate to the client102,104,106. DNS C performs this analysis by knowing the IP address of the downstream DNS server204, DNS A which it assumes is located near the client102,104,106. By using this IP address and combining it with internal knowledge of the network100topology and assignment of IP addresses, DNS C306can determine the geographically optimal cache server302,304to serve the requested content to the client102,104,106.

An exemplary transaction is further depicted byFIG. 3. In this exemplary transaction, Client3106wishes to request content from Server1108. Client3106will establish the IP address of the source of the desired content using the standard DNS translation system described above, labeled “A1”, “B”, “C”, “D”, “E”, “F”, “G”, “H1.” Once Client3106has the IP address of Server1108, it will generate a request for the initial HTML code file of the desired Web page and Server1108will respond with the data. Client3106will then request a particular separately stored file associated with the Web page by reading the URL from the HTML code file and translating the domain name contained therein. As noted above, this URL comprises the domain name of the content delivery service as well as an identifier which identifies the content being requested (since the content delivery service typically handles many different servers108). Client3106will generate another translation request to DNS A204, labeled “I1” and “J.” DNS A204will attempt to translate the given domain name but will fail because the content delivery service has set all of its translations to have a TTL=0. Therefore, DNS A204will be required to contact DNS C306which is provided by the content delivery service, labeled “K” and “L.” Note that DNS A204may be required to contact DNS top202in order to locate the IP address of DNS C306. DNS C306receives the translation request and knows the IP address of DNS A204, which was given as the return address for the translation. Using the IP address of DNS A204, DNS C306figures out which cache server302,304is geographically proximate to Client3106, in this case, Cache C2304. An appropriate IP address is then returned to by DNS C306to DNS A204and subsequently returned to Client3106. Client3106then formulates its request for the separately stored data but, unwittingly, uses the IP address of the cache server C2304. Cache server C2304receives the request and serves the desired content as described above.

FIG. 3further illustrates a second exemplary transaction sequence which discloses a flaw in the depicted content delivery method. In this example, Client1102wishes to request content from Server1108. Client1102is a wireless or mobile client which is coupled with service provide118at POP2but is bound to DNS A204provided by service provider120. In this example, all of the translation and request transactions occur as in the above example for Client3106. The translation request to identify the IP address of the separately stored content will be handled by DNS A204which will then hand it off to DNS C306as described above. However, DNS C306will then attempt to identify a geographically proximate cache server302,304based on the IP address of DNS A204which is not located near Client1102in this example. Therefore DNS C306will return a translation directing Client1102to cache server C2304when in fact, the optimal cache server would have been cache server C1302. With more and more wireless and mobile user utilizing the Internet, mis-optimized re-direction of content delivery will happen more frequently. Furthermore, there may be cases where the Client102,104,106is dynamically bound to a DNS translator associated with whatever POP114,116they are connecting to. While this may appear to solve the problem, the content delivery service is still basing its redirection determination on an indirect indicator of the location of the client102,104,106. However, the IP address of the DNS translator may still fail to indicate the correct geographic location or the correct logical location (based on the topology of the network100) of the client102,104,106in relation to the DNS translator. A more accurate indicator of the client's102,104,106physical geographic location and/or network logical location is needed in order to make an accurate decision on which cache server302,304to redirect that client102,104,106to.

V. The First Embodiment

Referring now toFIG. 4, there is depicted a first embodiment of an enhanced DNS system to facilitate the operation of content delivery services by eliminating the dependency on the geographic location of the downstream DNS server. In addition to what is shown inFIG. 3, the embodiment shown inFIG. 4further adds an edge server402coupled with the routing equipment206and POP's114of an affiliated service provider120and preferably located within the affiliated server provider's120facilities. In one alternative embodiment, the edge server402is integrated with a router. In another alternative embodiment, the edge server is integrated with a generally accessible DNS translation server such as DNS A1204. The edge server402is capable of monitoring the network traffic stream passing between the POP's114and the network100, including the service provider's120hardware, such as the cache208and the DNS translation server204, DNS A. The edge server402is further capable of selectively intercepting that traffic and preventing it from reaching its intended destination, modifying the intercepted traffic and reinserting the modified traffic back into the general network traffic stream. It is preferred that the facilities and capabilities of the edge server402be provided to content delivery services and or Web servers108on a fee for services basis as will be described below. Further, it is preferred that an edge server402be provided at every major service provider118,120so as to be able to selectively intercept network traffic at all possible POP's114,116of the network100.

Referring toFIG. 4A, the edge server402includes a request interceptor404, a request modifier406, and a request forwarder408. The edge server402preferably includes one or more processors, a memory coupled with the processors and one or more network interfaces or other interfaces, also coupled with the processors and operative to couple or integrate the edge server402with the routing equipment of the service provider120. Optionally, the edge server402may include secondary storage including a second memory such as a cache memory, hard disk or other storage medium. Further, the processors of the edge server402may be dedicated processors to perform the various specific functions described below. The edge server402preferably further includes software and/or firmware provided in a read only memory or in a secondary storage which can be loaded into memory for execution or, alternatively, executed from the secondary storage by the processors, to implement the various functions as detailed below. To further improve performance, such software functionality may also be provided by application specific integrated circuits (“ASICs”). For example, an edge server402can comprise a Compaq TaskSmart™ Server manufactured by Compaq Corporation, located in Austin, Tex. The TaskSmart™ Server can include an Intel IXA1000 Packet Processor manufactured by Intel Corporation, located in Santa Clara, Calif. to perform the traffic monitoring and port specific traffic interception functions as well as the security applications as detailed below. The TaskSmart™ Server can further include a PAX.port 1100™ classification adapter manufactured by Solidum Corporation, located in Scotts Valley, Calif., which can receive intercepted DNS translation requests from the packet processor and, utilizing a look up table (preferably stored in a memory providing high speed access), determine whether or not the request is associated with a subscribing server108, as described below. The classification adapter can attempt to resolve the DNS request or hand it off to a general processor such as an Intel Pentium III™ or other general purpose processor for further operations as detailed below. An exemplary edge server402may have six 9.1 GB hot pluggable hard drives preferably in a RAID or other redundant configuration, two redundant hot pluggable power supplies, five 10/100 Ethernet ports and 1 GB of main memory and capable of handling in excess of 1250 requests per second.

The request interceptor404listens to the network traffic passing between the POP's114of the affiliated service provider120and the network100and selectively intercepts DNS translation requests generated by any of the clients102,104coupled with the particular affiliated service provider120. Such interception is preferably accomplished by identifying the destination “port” of any given data packet generated by a client102,104, alternatively other methods of identifing a packet type may be used such as by matching the destination address with a list of known DNS translation server addresses. A port in programming is a “logical connection place” and specifically, within the context of the Internet's communications protocol, TCP/IP, a port is the way a client program specifies a particular applications program on a computer in a network to receive its requests. Higher-level applications that use the TCP/IP protocol such as HTTP, or the DNS translation protocol, have ports with pre-assigned numbers. These are known as “well-known ports” and have been assigned by the Internet Assigned Numbers Authority (IANA). Other application processes are given port numbers dynamically for each connection. When a service (server program) initially is started, it is said to bind to its designated port number. As any client program wants to use that server, it also must request to bind to the designated port number. Port numbers are from0to65536. Ports0to1024are reserved for use by certain privileged services. For the HTTP service, port80is defined as a default and it does not have to be specified in the Uniform Resource Locator (URL). In an alternative embodiment, the routing equipment206of the service provider120is programmed to forward all DNS translation requests to the edge server402. The request interceptor404can then choose which DNS translation requests to intercept as described below. This alternative routing scheme may implemented through a traffic routing protocol such as a Domain Name System Translation Protocol (“DNSTP”). This protocol is implemented in similar fashion to the Web Cache Control Protocol (“WCCP”) which is used to redirect HTTP requests to proxy cache servers based on the specified port in the packet.

DNS translation requests are identified by the port number53. The request interceptor404monitors for all data traffic with the specified port number for a DNS translation request. It then is capable of intercepting DNS translation requests generated by clients102,104such as computer workstations, wireless devices or internal DNS translators on a private network. The request interceptor404is aware of which content delivery services subscribe to the edge server402service and is operative to selectively intercept DNS translation requests associated with the subscribing content delivery service, i.e. contain translations intended to be translated by the DNS translator of the content delivery service or server108. The request interceptor404may provide a table or database stored in memory or other storage device where it can look up the service subscribers to determine whether the particular DNS translation request should be intercepted. It is preferred that the request interceptor404make this determination at “wire speed”, i.e. at a speed fast enough so as not to impact the bandwidth and throughput of the network traffic it is monitoring.

When a DNS translation request is generated by a client102,104to translate a domain name associated with the content delivery service, as described above for the modified HTTP slow start protocol, to retrieve the separately stored Web page content, that DNS translation request will be selectively intercepted by the request interceptor404of the edge server402. The interception will occur before it reaches the bound/destination DNS translation server bound to or specified by the client102,104. The request interceptor404will then pass the intercepted DNS translation request to the request modifier406.

The request modifier406modifies the DNS translation request to include additional information or indicia related to the client102,104so that the intelligent DNS translation server of the content delivery service or server108can make a more optimized decision on which of the geographically dispersed cache servers302,304would be optimal to serve the requests of the client102,104. This additional information can include the geographic location of the POP114or the characteristics of the downstream network infrastructure, such as whether the client102,104is connecting to the POP114via a modem connection or a broadband connection or whether the client102,104is a wired or wireless client, etc. It will be appreciated that there may be other information or indicia that the edge server402can provide to enhance the DNS translation request and this may depend on the capabilities of the subscribing content delivery services, and all such additional indicia are contemplated. It is preferable that the subscribing content service providers are familiar with the indicia data types, content and possible encoding schemes which the edge server402can provide so as to establish a protocol by which the data is transferred to the subscribing content delivery service. Such information is then recognized and used by the content delivery service to enhance their redirection. For example, by knowing the geographic location of the POP114as provided by the edge server402, the content delivery service does not need to rely on the IP address of the bound DNS server from which it receives the translation request (described in more detail below) and therefore will make a more accurate determination of which cache server302,304to choose. Similarly, by knowing the capabilities of the downstream network infrastructure from the POP114to the client102,104as provided by the edge server402, the content delivery service can redirect content requests by the client102,104to a cache server302,304with capabilities which match. For example, where the POP114to client102,104connection is a broadband connection, the client102,104can be directed to make its requests to a cache server302,304capable of utilizing the available bandwidth to the client102,104. In contrast, where the client102,104connects to the POP114via a modem/standard telephone line connection, the content delivery service can direct that client102,104to make its requests to an appropriate low speed cache server302,304so as not to waste the resources of high bandwidth cache servers302,304.

Once the DNS translation request has been modified, the request modifier406passes the DNS translation request to the request forwarder408. The request forwarder places the modified DNS translation request back into the general stream of network traffic where it can be routed to its originally intended destination, i.e. the bound or specified DNS translation server204,410bound to or specified by the originating client. The DNS translation server204,410will translate the request as described above, by contacting the DNS translation server306, DNS C associated with the content delivery service. As described above, the intelligent DNS translation server306of the content delivery service will see the modified request and utilize the information/indicia included by the edge server402to make a more optimal translation and cache server302,304assignment.

FIG. 4depicts an exemplary content delivery transaction between Client1102and Server1108. For the purposes of this example transaction, Client1102is bound to DNS translation server204, labeled “DNS A1.” Client1102initiates the HTTP slow start protocol as described above by making its initial request for an HTML Web page from Server1108. This initiation may require making several DNS translations as described above, labeled as “A”, “B1”, “C1”, “D1”, “E1”, “F1”, “G1”, “H.” Once the HTML Web page has been received by Client1102, it will begin to request the separately stored content associated with the Web page. As was discussed above, where Server1108has been “content enabled” and subscribes to the content delivery service, the URL's of the separately stored content will comprise the domain name of the content delivery service. As well, as discussed above, these domain names will require complete DNS translation all the way back to the DNS translation server306, DNS C of the content delivery service because the content delivery service ensures that all of its translations have TTL=0 and therefore cannot be stored in any given downstream DNS translation server. Therefore, Client1102will initiate a DNS translation for the URL of the separately stored content, labeled “I.” This DNS translation request will go through the POP114and to the routing equipment206of the service provider120. The edge server402will see this DNS translation request and identify the domain name of the content service provider as a subscriber to its service. The request interceptor404will then intercept the DNS translation request, labeled as “J.” The request interceptor404will pass the intercepted DNS translation request to the request modifier406which will append a geographic indication representing the physical geographic location of the edge server402or alternatively, other downstream network characteristics. Given that the edge server402is located geographically proximate to the POP's114, this information will more accurately represent the location of Client1102. Alternatively, while the edge server402may not be geographically proximate to the POP's114, it may be network proximate to the POP's114, i.e. there may be a minimal of network infrastructure between the POP's114and the edge server402. In some instances, while one device on a network may sit physically right next to another device on the network, the network topology may dictate that data flowing between those devices flow over a circuitous route to get from one device to the other. In this case, while the devices are physically close to one another, they are not logically close to one another. The edge server402is preferably familiar, not only with its geographic location within the context of the network100as a whole, but also its logical location. Using this information, the edge server402can further include information as to this logical location so as to enable, not only a geographically optimal redirection of Client1's102requests but also a network topology based optimized redirection.

The request modifier406will then pass the modified DNS translation request to the request forwarder408which will place the request back into the general traffic stream, and in this case, on its way to the original intended recipient, Client1's102bound DNS translation server204, DNS A1, labeled as “K1.” DNS A1204will then translate the modified DNS translation request as described above and return the translation to Client1102, labeled as “L1”, “M1”, “N1”, “O.” DNS C306, using the additional data provided by the edge server402, will supply a DNS translation redirecting Client1's102requests to Cache C2304which is the optimal cache server.

FIG. 4further depicts a second exemplary content delivery transaction between Client1102and Server1108. For the purposes of this second example transaction, Client1102is a wireless or mobile wired device connecting to a POP114provided by service provider120but is bound to DNS translation server410, labeled “DNS A2” provided by service provider118. Note that in the previous exemplary transaction above, Client1102was bound to DNS A1204, e.g., Client1102was a stationary computer or private network subscribing to the network100connection services of service provider120and using the POP's114provided by the service provider120and that service provider's120DNS translation server204, DNS A1. In the current example, Client1102is a subscriber to the network100connections services of service provider118but is currently roaming, i.e. geographically located in an area not serviced by a POP116provided by service provider118. Therefore Client1102must use a POP114provided by a service provider120, which for example, has an agreement to allow such connections from service provider's118customers. However, because DNS translation servers are bound to the Client102, i.e. the address of the preferred DNS translation server is programmed into the Client102, Client102will still use its programmed or bound DNS translation server, typically the DNS translation server provided by its service provider118, in this case DNS A2410.

As above, Client1102initiates the HTTP slow start protocol as described above by making its initial request for an HTML Web page from Server1108. This initiation may require making several DNS translations as described above but using DNS A2410instead of DNS A1204, labeled as transactions “A”, “B2”, “C2”, “D2”, “E2”, “F2”, “G2”, “H.” Once the HTML Web page has been received by Client1102, it will begin to request the separately stored content associated with the Web page. As was discussed above, where Server1108has been “content enabled” and subscribes to the content delivery service, the URL's of the separately stored content will comprise the domain name of the content delivery service. As well, as discussed above, these domain names will require complete DNS translation all the way back to the DNS translation server306, DNS C of the content delivery service because the content delivery service ensures that all of its translations have TTL=0 and therefore cannot be stored in any given downstream DNS translation server. Therefore, Client1102will initiate a DNS translation for the URL of the separately stored content, labeled “I.” This DNS translation request will go through the POP114and to the routing equipment206of the service provider120. The edge server402will see this DNS translation request and identify the domain name of the content service provider as a subscriber to its service. The request interceptor404will then intercept the DNS translation request, labeled as “J.” The request interceptor404will pass the intercepted DNS translation request to the request modifier406which will append a geographic indication representing the physical geographic location of the edge server402. Given that the edge server402is located geographically proximate to the POP's114, this information will more accurately represent the location of Client1102. Alternatively, while the edge server402may not be geographically proximate to the POP's114, it may be network proximate to the POP's114, i.e. there may be a minimal of network infrastructure between the POP's114and the edge server402. In some instances, while one device on a network may sit physically right next to another device on the network, the network topology may dictate that data flowing between those devices flow over a circuitous route to get from one device to the other. In this case, while the devices are physically close to one another, they are not logically close to one another. The edge server402is preferably familiar, not only with its geographic location within the context of the network100as a whole, but also its logical location. Using this information, the edge server402can further include information as to this logical location so as to enable, not only a geographically optimal redirection of Client1's102requests but also a network optimized redirection.

The request modifier406will then pass the modified DNS translation request to the request forwarder408which will place the request back into the general traffic stream, and in this case, on its way to the original intended recipient, Client1's102bound DNS translation server410, DNS A2, labeled as “K2.” DNS A2410will then translate the modified DNS translation request as described above and return the translation to Client1102, labeled as “L2”, “M2”, “N2”, “O.” In this case, without the additional data provided by the edge server402, DNS C306would have made its redirection determination based on the IP address of DNS A2410, as described above. This would have resulted in Client1102being redirected to Cache C1302instead of the optimal cache for its location. However, DNS C306, using the additional data provided by the edge server402is able to supply a DNS translation redirecting Client1's102requests to Cache C2304which is the optimal cache server.

VI The Second Embodiment

Referring toFIG. 5, there is depicted a second embodiment of an enhanced DNS system to facilitate content delivery which is not dependent upon the geographic location of the downstream DNS server and is capable of enhancing the HTTP slow start protocol.

FIG. 5shows Clients1and2102,104coupled with POP's114, POP1A and POP1B of service provider120. As described above, service provider120includes routing equipment206, Cache208and DNS translation server204to facilitate coupling the POP's114with the network100. In addition, service provider120further includes an edge server502and an edge cache508. In one alternative embodiment, the edge server502is integrated with a router. In another alternative embodiment, the edge server502is integrated with a generally accessible DNS translation server such as DNS A204. In still another alternative embodiment, the edge server502can be integrated with the edge cache504or each can be provided as separate devices or the edge server502can utilize an existing cache server208provided by the service provider120. For clarity, a number of the components ofFIG. 4have been omitted fromFIG. 5.

Referring toFIG. 5A, the edge server502further includes a request interceptor504and an edge DNS translation server506. It is preferred that the facilities and capabilities of the edge server502be provided to Web servers108on a subscription or fee for services basis as will be described below. It is further preferred that an edge server502and edge cache508be provided at every service provider118,120or at every major network100intersection so as to provide coverage of every POP114,116on the edge124of the network100. The edge server402preferably includes one or more processors, a memory coupled with the processors and one or more network interfaces or other interfaces, also coupled with the processors and operative to couple or integrate the edge server502with the routing equipment of the service provider120. Optionally, the edge server502may include secondary storage including a second memory such as a cache memory, hard disk or other storage medium. Further, the processors of the edge server502may be dedicated processors to perform the various specific functions described below. The edge server502preferably further includes software and/or firmware provided in a read only memory or in a secondary storage which can be loaded into memory for execution or, alternatively, executed from the secondary storage by the processors, to implement the various functions as detailed below. To further improve performance, such software functionality may also be provided by application specific integrated circuits (“ASICs”). For example, an edge server502can comprise a Compaq TaskSmart™ Server manufactured by Compaq Corporation, located in Austin, Tex. The TaskSmart™ Server can include an Intel IXA1000 Packet Processor manufactured by Intel Corporation, located in Santa Clara, Calif. to perform the traffic monitoring and port specific traffic interception functions as well as the security applications as detailed below. The TaskSmart™ Server can further include a PAX.port 1100™ classification adapter manufactured by Solidum Corporation, located in Scotts Valley, Calif., which can receive intercepted DNS translation requests from the packet processor and, utilizing a look up table (preferably stored in a memory providing high speed access), determine whether or not the request is associated with a subscribing server108, as described below. The classification adapter can attempt to resolve the DNS request or hand it off to a general processor such as an Intel Pentium III™ or other general purpose processor for further operations as detailed below. An exemplary edge server502may have six 9.1 GB hot pluggable hard drives preferably in a RAID or other redundant configuration, two redundant hot pluggable power supplies, five 10/100 Ethernet ports and 1 GB of main memory and capable of handling in excess of 1250 requests per second.

As described above, the request interceptor504operates to selectively intercept DNS translation requests associated with its subscribing Web server108generated by clients1and2102,104. Alternatively, DNS translation requests can be forwarded to the request interceptor504by the service provider's120routing equipment206as described above. In this embodiment, however, because the request interceptor504is monitoring for DNS translation requests associated with the server108and not some separate content delivery service, the request interceptor504will selectively intercept all DNS translation requests, including the initial request to retrieve the HTML Web page file and begin the HTTP slow start protocol. Again, the request interceptor504preferably includes a database or table stored in a memory or other storage medium which indicates the domain names or other identification information of subscribing servers108.

The selectively intercepted DNS translation requests are passed by the request interceptor504to an internal edge DNS translation server506. The internal edge DNS translation server506then translates the given domain name into the IP address of the edge cache508and returns this translation to the client102,104, labeled “A”, “B”, “C”, “D.” This effectively redirects the client102,104to make all of its content requests from the edge cache508. This differs from a proxy server, where the client102,104is not redirected but either thinks that it is communicating with the server108(in the case of a transparent or server side reverse proxy server) or has been specifically programmed to communicate its requests to the proxy server (in the case of a client side forward proxy server). The edge cache508operates as a normal cache server as described above, attempting to satisfy content requests from its cache storage. However, when the requested content is not available in the cache storage (a cache miss), the request is proxied to the server108by the edge cache508and/or edge server502, i.e. the edge cache508and/or edge server502make the request on behalf of the client102,104. This is in contrast to normal cache servers which forward the request from the client102,104onto the server108upon a cache miss.

Cache misses are handled as described above, the edge server502or alternatively the edge cache508makes its own request for the uncached content from the server108. Alternatively, other algorithms can be used to reduce or eliminate cache misses including mirroring the content of the server108coupled with periodic updates either initiated by the edge server502or edge cache508or periodically pushed to the edge cache508by the server108. In another alternative embodiment, the server108can update cached content when it determines that such content has changed or can provide time durations or other form of expiration notification after which the edge cache508purges the content. Where the content expires or is otherwise purged from the edge cache508, the next request for that content will miss and cause a reload of the content from the server108. One of ordinary skill in the art will recognize that there are many caching algorithms which may be used to maintain cache coherency. It is further preferable that the edge cache508maintain a replacement policy of replacing the oldest data in the cache when the cache is full. Again, one of ordinary skill in the art will recognize that there are many different cache replacement algorithms that may be used.

In this way, the edge server502and edge cache508act similarly to a forward or reverse proxy server for all of its subscribing servers108. Generally, a reverse proxy server is a proxy server that hides multiple source servers behind a single address. A reverse proxy server allows a content provider to serve their content from multiple host computers without requiring users to know the addresses of each of those computers. When a user makes a request to a content provider, they use the address of the reverse proxy server. The reverse proxy server intercepts the requests for content from the source and redirects those requests to the appropriate host computer within the content provider. The redirection can be based on a which machine contains the requested content or can be used to balance the request load across multiple mirrored servers. A forward proxy server sits between a workstation user and the Internet so that the enterprise can ensure security, administrative control and caching services. A forward proxy server can be associated with a gateway server which separates the enterprise network from an outside network such as the Internet. The forward proxy server can also be associated with a firewall server which protects the enterprise network from outside intrusion. Forward proxy servers accept requests from their users for Internet content and then request that content from the source on behalf of the user. The forward proxy server modifies the identity of the requester (typically by altering the internet protocol address of the requester) to be that of the forward proxy server. A user workstation typically must be configured to use a proxy server. A forward proxy server can also be a cache server (see above).

A major distinction between the edge server502and a proxy server is that there is no one address of the edge server502. The edge server502effectively needs no address because it intercepts the necessary network traffic. Therefore, clients102,104do not need to know of the existence of the edge server502and can operate as they normally do, making content requests of servers108. However, when they request content from a subscribing server108, that content will be transparently provided instead by the edge server502and edge cache508.

Effectively, the edge server502and edge cache508isolate the sub-network comprising the service provider120, the POP's114and the clients102,104from the subscribing server108, i.e. the clients102,104are prevented from any direct contact with server108. Should the client102,104request uncached content, it is the edge cache508and not the client102,104which will request that content from the server108. Furthermore, the edge server502and edge cache508can ensure that the request is valid and legitimate before communicating with the server108. This “trusted” relationship between the edge server502/edge cache508and the subscribing servers acts as additional security for the servers108. Those servers108can be programmed to ignore content requests from clients102,104since they know that only valid content requests can come from an edge server502/edge cache508. Furthermore, the edge server502alleviates the load on the server's108internal DNS translation server210because all DNS translations will be handled by the internal edge DNS translator506.

The effect of the edge server502and edge cache508is faster DNS translations and better response times to requests. The edge cache508can serve the initial HTML Web page file to the requesting client102,104and immediately begin the process of requesting the separately stored content (if not already in the cache) from the server108in order to speed up the HTTP slow start protocol. Furthermore, it is preferred that the edge caches508located through out the edge124of the network100be capable of communicating and sharing cached data. In this way, the edge caches508can further reduce the demands placed on the subscribing servers108.

Notice, however, that because the edge server502intercepts translation requests, a client102,104that already knows the IP address of the server108, can still directly communicate with that server108via the network100. In this case, the server108can choose to disconnect itself from the network100generally (or refuse to accept any inbound content requests from the network100that do not originate from an edge server502/edge cache508, however such origination may be forged). The edge server502and edge cache508can then connect with the server108using private proprietary communications links which are not available to clients102,104.

The edge server502and edge cache508can also provide load balancing and security services to the subscribing servers. For example, open source load balancing techniques available from eddieware.org can be implemented in the edge server502. Where a particular server108comprises multiple sub-servers, the edge cache508can be programmed to request uncached content from the sub-servers so as to spread the load on each sub-server.

Further, because the edge server502acts as the DNS translator server for its subscribers, it can detect and absorb any security attacks based on the DNS system, such as distributed denial of service attacks, “DDoS.” A Denial of Service Attack (“DoS” or Distributed DoS “DDoS”) is an incident in which a user or organization is deprived of the services of a resource they would normally expect to have. Typically, the loss of service is the inability of a particular network service, such as e-mail, to be available or the temporary loss of all network connectivity and services. In the worst cases, for example, a Web site accessed by millions of people can occasionally be forced to temporarily cease operation. A denial of service attack can also destroy programming and files in a computer system. Although usually intentional and malicious, a denial of service attack can sometimes happen accidentally. A denial of service attack is a type of security breach to a computer system that does not usually result in the theft of information or other security loss. However, these attacks can cost the target person or company a great deal of time and money.

There are two related varieties of DDoS attacks. One attempts to shut down the DNS system in relation to the target site so that no legitimate user can obtain a valid translation and make a request from the site. Another type of DDoS attack attempts to overload the server108directly with a flood of content requests which exceed the capacity of the server. However, it will be appreciated that, by placing edge servers502and edge caches508so that all POP's114,116are covered and can be monitored, DDoS attacks can never reach the server108itself and will always be detected close to their origination by an edge server502where they can be stopped and isolated. It will be further apparent that where a DDoS attack cripples one edge server502and its associated sub-network, the remaining edge servers502at other service providers118,120(and their associated sub-networks) can remain operational and therefore the server108suffers minimal impact as a result of the DDoS attack. In addition, it is preferred that the edge server502and edge cache508provide bandwidth and processing power far in excess of that needed by the sub-network comprising the POP's114and service provider120in order to be able to absorb DDoS attacks and not be crippled by them.

It will further be appreciated, that the edge server502can incorporate the capabilities of the edge server402by providing enhanced DNS translations for subscribing content delivery services as well as the enhanced content delivery itself for subscribing servers108.

In addition, where client102,104is a private network such as an intranet, which has its own internal DNS translation server which is making DNS translation requests out to the network100, the edge server502can set its returned DNS translations to have a TTL=0 so that the client's102,104internal DNS server must always forward DNS translation requests to subscribing server108upstream where they can be intercepted by the edge server502. Otherwise, the caching function of the client's102,104internal DNS translation server would prevent proper DNS translations from occurring. Notice that this is not an issue in the first embodiment, because as discussed above, the content delivery service performs the DNS translations and always sets translation TTL=0 to facilitate its operation.

VII The Third Embodiment

Referring toFIG. 6, there is depicted an enhanced network100to facilitate content delivery and network100security.FIG. 6depicts clients1and2102,104connected with POP's114, POP2A and POP2B of service provider118effectively forming a sub-network of the network100. Further, clients3and4106,612are shown connected to POP's116, POP1A and POP1B of service provider120. Further, service providers118,120each include an edge server602A,602B and an edge cache604A,604B coupled with the routing equipment206of the service providers118,120so as to be able to intercept all network traffic flowing between the POP's114,116and the network100. In one alternative embodiment, the edge server602is integrated with a router. In another alternative embodiment, the edge server602is integrated with a generally accessible DNS translation server such as DNS A1204or DNS A2410. In still another alternative embodiment, the edge server602is integrated with the edge cache604, or alternatively they can be implemented as separate devices or the edge server602can utilize a cache server208provided by the service provider118,120(not showing inFIG. 6). It is preferred that the facilities and capabilities of the edge servers602be provided to Web servers108on a subscription or fee for services basis as will be described below. It is further preferred that an edge server602and edge cache604be provided at every service provider118,120or at every major network100intersection so as to provide coverage of every POP114,116on the edge124of the network100, i.e. to minimize the size of the sub-network downstream from the edge server602.

Referring toFIG. 6A, the edge server602further includes a request filter606, a request interceptor608and a proxy server and/or internal DNS translation server610. The edge server602is capable of operating similarly to the edge server402and502of the previous embodiments. However, the edge server602is further capable of intercepting data traffic at the packet level based on the source or destination IP address contained within the packets flowing past the edge server602. In this way, the edge server602is able to provide complete isolation of its subscribing servers108,110. Any network traffic destined for a subscribing server108,110can be intercepted by the edge server602and acted upon. The edge server602preferably includes one or more processors, a memory coupled with the processors and one or more network interfaces or other interfaces, also coupled with the processors and operative to couple or integrate the edge server602with the routing equipment of the service provider120. Optionally, the edge server602may include secondary storage including a second memory such as a cache memory, hard disk or other storage medium. Further, the processors of the edge server602may be dedicated processors to perform the various specific functions described below. The edge server602preferably further includes software and/or firmware provided in a read only memory or in a secondary storage which can be loaded into memory for execution or, alternatively, executed from the secondary storage by the processors, to implement the various functions as detailed below. To further improve performance, such software functionality may also be provided by application specific integrated circuits (“ASICs”). For example, an edge server602can comprise a Compaq TaskSmart™ Server manufactured by Compaq Corporation, located in Austin, Tex. The TaskSmart™ Server can include an Intel IXP 1200 Packet Processor manufactured by Intel Corporation, located in Santa Clara, Calif. to perform the traffic monitoring and port specific traffic interception functions as well as the security applications as detailed below. The TaskSmart™ Server can further include a PAX.port 1100™ classification adapter manufactured by Solidum Corporation, located in Scotts Valley, Calif., which can receive intercepted DNS translation requests from the packet processor and, utilizing a look up table (preferably stored in a memory providing high speed access), determine whether or not the request is associated with a subscribing server108, as described below. The classification adapter can attempt to resolve the DNS request or hand it off to a general processor such as an Intel Pentium III™ or other general purpose processor for further operations as detailed below. An exemplary edge server602may have six 9.1 GB hot pluggable hard drives preferably in a RAID or other redundant configuration, two redundant hot pluggable power supplies, five 10/100 Ethernet ports and 1 GB of main memory and capable of handling in excess of 1250 requests per second.

For valid content requests from clients102,104,106,612, the edge server602in combination with the edge cache604acts just like the edge server502and edge cache508in the previous embodiment. Such requests will be redirected and served from the edge cache604. Again an edge cache604A at one service provider118can share cached data from another edge cache604B located at another service provider120. In this way, a comprehensive content delivery service is created which completely isolates the core122of the network100from untrusted and unregulated client102,104,106,602generated network traffic. Such traffic is isolated at the edge124of the network100within the sub-network below, i.e. downstream from the edge server602where it can be contained, monitored and serviced more efficiently. In terms of the economics of the network100then, the load on the expensive high bandwidth communications resources located at the core122of the network100is reduced and maintained at the edge124of the network where bandwidth is less expensive.

In addition, the edge server's602packet level filter606prevents any client102,104,106,612from directly communicating with any subscribing server108,110even if that client102,104,106,612has the IP address of the server108,110. The packet level filter606will see the destination IP address in the network traffic and selectively intercept that traffic.

Once traffic is intercepted, the edge server602can perform many value added services. As described above, the edge server602can perform DNS translations and redirect clients102,104,106,612to make their content requests to the edge cache604. The edge server602can also monitor the data transmission being generated by clients102,104,106,602for malicious program code, i.e. program code that has been previously identified (by the server108or a third party such as a virus watch service) as unwanted, harmful, or destructive such as viruses or other unauthorized data being transmitted. For example, if the edge server602A detects a data packet whose origin address could not have come from the downstream network or POP's114to which it is connected, the edge server602A knows that this data packet must be a forgery and can eradicate it or prevent it from reaching the network100. For example, where a computer hacker surreptitiously installs a program on client1102to generate a DDoS attack on server1108but appear as if the attack is coming from client4612, the edge server602A will see the packets generated by Client1102and also see that they contain a source address associated with a client, in this case client4612, which based on the address, could not have come from any POP114of the service provider118to which the edge server602A is connected. In this case, the edge server602A can eliminate that packet and then attempt to identify the actual originating client, in this case client1102, so that the attack can be stopped and investigated. In addition, because general network traffic is unable to reach the subscribing servers108,110, hackers would be unable to access those servers in attempts to steal valuable data such as credit card numbers.

Furthermore, to enhance security, as described above, the connections between the edge servers602A,602B and edge caches604A,604B can alternatively be made through private communications links instead of the publicly accessible network100. In this way, only trusted communications over secure communications links can reach the servers108,110. This security in combination with the multiple dispersed edge servers602A,602B and edge caches604A,604B covering the edge124of the network100ensures that the subscribing servers108,110will be able to serve their content under high demand and despite security threats.

In operation, the request filter606pre-filters traffic before receipt by the request interceptor608. The request filter606preferably provides subscriber detection, “ingress filtering” capability, and cache hit determination. The request filter606first determines whether or not the traffic it is monitoring is associated with a subscribing/affiliated server108,110. If not, this traffic is ignored and allowed to proceed to its final destination. The request filter606preferably comprises a table or database of subscribers stored in a memory or other storage device. If the traffic is associated with a subscribing server108,110, the request filter606then performs ingress filtering by determining whether the packet originated downstream from the edge server602, i.e. from the downstream sub-network, the POP's114,116affiliated with this particular edge server602or from upstream which indicates that they did not originate from an affiliated POP114,116and therefore are suspect and most likely invalid. Packets originating from upstream are preferably eradicated. Valid downstream originating packets are then analyzed for the content/nature of the packet. If the packet comprises a content request, the request filter606can determine if the request can be satisfied by the edge cache604. Preferably, the request filter606maintains a table or database in memory or other storage medium of the edge cache604contents. If the packet contains a request that can be satisfied from the edge cache604, the request filter606will hand the packet/request off to the edge cache604. The edge cache604operates similarly to the edge cache508of the above embodiment. If the packet comprises a DNS translation request or a content request which cannot be satisfied by the edge cache604, the request filter606hands the packet/request off to the internal request transmitter/proxy server/DNS translation server610to proxy, e.g. transmit, the request to the intended server or provide a DNS translation. The server108responds with the requested content to the edge server602and/or edge cache604which then returns the response to the requesting client102,104,106,612and/or caches the response. It is preferred that the request filter606be able to perform its functions at “wire speed”, i.e. a speed at which will have minimal impact on network100bandwidth and throughput. The request filter606then further alleviates the processing load on the internal DNS translator/proxy server610of the edge server602.

It will be appreciated that, in any of the above embodiments, additional upstream edge servers and edge caches can be provided at major peering points to provide a layered hierarchy of cache storage tiers which further enhances the response times. In addition, a hierarchy of edge servers and edge caches can be used to handle any overload of one or more downstream edge servers and edge caches or to handle spill over of capacity or even a complete failure of one or more edge servers or edge caches. By forming a hierarchy of edge servers and edge caches, the network100and service provider118,120fault tolerance is increased and enhanced.

The edge servers and edge caches therefore act similarly to proxy servers. However, where a forward proxy server alters the source address of a given content request (effectively making that request on behalf of a client), an edge server merely adds additional data to the source address which can then be used by upstream content delivery services for more accurate redirection or intercepts and substitutes the address translation transactions to redirect a client to make its requests from a nearby edge cache. Therefore, there is no need to intercept content requests since those requests will have been already directed to the edge cache. While a reverse proxy server is typically tightly bound with a group of servers which belong to a single entity or comprise a single Web site, the edge server performs reverse proxy functions but for any entity or Web site which subscribes to the service. Furthermore, no changes are required to the client or the subscribing servers. Once the subscriber tables are updated within the edge servers, the edge server will then start to perform its functions on the network traffic of the subscribing Web server. The subscribing Web server does not need to alter their Web site in any way and the client does not need to be pre-programmed to communicate with the edge server.

Further the network of edge servers and edge caches located at every major network intersection so as to cover every POP, thereby minimizing the size of the sub-network downstream from the edge server, forms a security barrier which isolates the core infrastructure and servers of the network/internet from the edge where the clients are located. In addition to isolation, network performance is enhanced by virtually placing the content and services of core content providers at network-logically and physically-geographic proximate locations with respect to the clients. Content is placed as close as possible to the requesters of that content resulting in enhanced response times and enhanced throughput. This results in reduced load, congestion and bandwidth consumption of the expensive high capacity backbone links which form the core of the network. Trivial network traffic is maintained at the edge of the network speeding response times and throughput. In addition, the edge caches are capable of communicating with one another and sharing cached data, thereby greatly enhancing the caching effect and further reducing the load on the core of the network.

By further making the edge servers more intelligent, such as by adding additional processing capacity, dynamic load balancing services can be provided to the subscribing servers which can respond to changing demands for content. The edge servers and edge caches are further located to minimize the number of downstream clients, thereby forming sub-networks which can isolate and contain network traffic. This allows security services to be provided by isolating security threats to the smallest possible portion of the network generally while leaving the remaining portions of the network fully operational. Further, would be hackers are prevented from being able to directly access a subscribing server in an attempt to break in and steal valuable data. Therefore, even where a particular server has a security hole, the data stored there will still be protected. In addition, the edge server is aware of its physical/geographic location and its logical location within the network hierarchy allowing it to enhance content redirection services as clients switch to wireless connectivity or otherwise become more mobile in relation to their service providers. Finally, the provision of a decentralized DNS enhancement system, as provided by the presently preferred embodiments, reduces the load on the existing DNS system and on subscribing servers' internal DNS systems as well as provides a distributed defense against DNS based denial of service attacks. Such attacks can be isolated to the smallest portion of the network possible and closest to the attack'source while the remaining portions of the network remain unaffected. Further, by isolating the attack, the source of the attack can be more easily pinpointed and investigated. Traffic can be monitored for unauthorized or malicious program code, i.e. program code previously identified as unwanted, harmful or destructive, such as the placement of zombies or virus programs. Such programs can be detected and eradicated before they can make it to their intended destination.

In addition, the provision of the decentralized DNS enhancement system, as provided by the presently preferred embodiments, provides an infrastructure which may be used to supplant the existing DNS system and allow the creation of new domain names and a new domain name allocation service. New services such as a keyword based DNS system may also be provided to further increase the ease of use of the network100and which do not rely on any modifications to a user's Web browser program (i.e. remain transparent to both the client and the content provider). A user's attempt to request content from a subscribing content provider using a new domain name provided by this new DNS system would be intercepted prior to reaching the existing DNS system and be properly translated so as to direct the user to the content provider. Alternatively, the request may be redirected to an edge server and edge cache which proxies the request for the user to the content provider. Such a system allows the content provider to remain a part of the network100, i.e. remain connected to the Internet and maintain their access within the existing DNS system, or they may choose to completely disconnect from the network100altogether and utilize proprietary communications links to the network of edge servers and edge caches to provide users/clients with access to their content.

It will be further appreciated by one of ordinary skill in the art that the provision of numerous distributed edge servers and edge caches encircling the core of the network100provides a secure decentralized infrastructure on which service applications can be built. Through the provision of additional application and data processing capabilities within the edge servers, service applications such as user applications (for example, content monitoring/filtering, advertising filtering, privacy management and network personalization), e-commerce applications (such as regional and local electronic store fronts, distributed shopping carts or advertising distribution), distributed processing applications, database access applications (such as distributed enterprise database access), communications applications (such as electronic mail, identity authentication/digital signatures, anti-spam filtering and spam source detection, voice telephony and instant messaging), search engine applications, multimedia distribution applications (such as MP3 or MPEG distribution and content adaptation), push content applications (such as stock quotes, news or other dynamic data distribution), network applications (such as on-demand/dynamic virtual private networks and network/enterprise security), etc. can be implemented. These applications can be implemented with minimal hardware at the network100core122because much of the processing load and bandwidth demands are distributed out at the edge124of the network100. Further, any application where decentralization of the client interface from the back-end processing enhances the application can be applied on a wide scale to the edge server infrastructure to reduce the centralized demands on the service providers.

VIII. The Fourth Embodiment

The above embodiments are all based upon the interception of packets off the network and the subsequent processing and determination of a course of action to take with those intercepted packets. As was described above, this may include selective interception of packets, selective modification of those intercepted packets and the subsequent release/reinsertion of the modified packets back into the general stream of network traffic. Selective interception includes the temporary interception of all packets presented on the inputs of the edge device and performing an initial evaluation to determine whether the packet should be immediately released or permanently intercepted for further processing. The determination of whether or not a particular packet should be permanently intercepted and the further processing/modification and/or subsequent release of the temporarily held packet are discussed in more detail below.

The embodiments disclosed above involve coupling an edge server or similar device with the routing equipment of an Internet service provider to facilitate packet interception at a point as close to the POP's as possible. This allows for early and reliable packet interception and further ensures some measure of reliability in determining the origination of a particular packet, the advantages of which are described above. Alternatively, it was noted above that the interception of packets may also take place at other upstream locations. It will be appreciated that the optimal placement of the disclosed embodiments is at any point within the network traffic flow which is most likely to see all of the relevant packets that are to be intercepted flow through.

In addition to the above embodiments, many other solutions to the Internet's problems involve the use of such edge/packet interception devices to process, route and deliver packets. Examples would include web switches, server load balancing, DNS enhancement, quality of service enhancement, and content delivery enhancement such as caching and mirroring applications. One exemplary device is the WebSwitch, manufactured by Alteon Web Systems, located in San Jose, Calif., which looks for packets with a port address of 53 indicating a DNS request. The Redirector intercepts and re-directs those DNS requests to alternate DNS servers. Another exemplary device is the Edge Server, manufactured by CloudShield Technologies, Inc., located in San Jose, Calif. (and described in more detail above). The Edge Server also intercepts DNS requests but performs its interception selectively by analyzing the application data layer of the packets in addition to the header data layer. Any portion of the packet may be analyzed. Implementing these applications and enhancements requires intercepting packets as they flow over the network prior to their receipt by their intended destination, processing the packet contents to determine a course of action and then performing that course of action, as was described.

As described above, it is optimal, in most Internet enhancement applications, to intercept and process packets close to their source before they enter the general stream of Internet traffic and diverge or alternatively, at one or more “choke points” through which all of the relevant packets must flow. For many of the above applications, it is desirable to intercept packets before they are routed beyond the edge of the Internet. However, as more and more of these solutions are developed, there will be more and more demand to intercept and process packets at the edge of the Internet or at critical packet switching choke points, such as Network Access Points (“NAP's ”). In reality, this means that more and more solution providers will want access to the equipment of the Internet Service Providers or NAP providers, at the edge of the Internet or in control of the desired choke points, to install their packet interception devices, causing new problems in the process.

As will be appreciated, in order to intercept a packet flowing from one point to another, an intercepting device must be logically and/or physically installed in series with the packet flow so that all packets must flow through the device. The intercepting device then intercepts the packets as they flow from point to point and determines what actions it will take with the packets. The cost of introducing this intercepting device, then, is the latency added by the processing time that it takes to determine the course of action. This latency can be quantified by the degradation in packet throughput from the ideal “wire speed” caused by the processing time of the device. As can be seen, as more and more intercepting devices are introduced, each device must be connected in series with the others and each adds additional processing latency to the overall packet flow. Further, if the processing performed by such devices cannot match or exceed the speed at which data is flowing, the wire speed, network performance will suffer. Internet service providers may be unwilling to introduce such additional overhead within their sub-networks and therefore may refuse to allow edge devices to be installed. Further, even if the benefits outweigh the additional latencies introduced, each additional device adds an additional possible failure point which can bring down the service providers entire network, a risk Internet service providers may be unwilling to take. In addition, since each intercepting device is connected in series with the others, each device (except for the first device in the chain) must wait for the upstream devices to process a given packet before processing the packet itself. This may cause contention for the service provider when determining which device to place ahead of another in the packet flow. Finally, the physical and/or electrical limitations of the service provider's hardware may prevent the installation of multiple edge/intercepting devices.

As can be seen from the above embodiments, edge devices generally perform the basic functions of intercepting packets from the general flow of network traffic, processing the intercepted packets and potentially reinserting new or modified packets back into the general flow of network traffic. In general, it is the choice of which packets to intercept and the subsequent processing performed by each edge/packet intercepting device on the intercepted packets which distinguishes each device.

Referring now toFIG. 7, there is shown a fourth embodiment of an edge adapter/packet interceptor system700which provides a scalable and reliable connection for multiple edge/packet interception devices to the routing equipment of the Internet Service Provider without introducing additional network latency or potential failure points to the packet flow. The edge adapter/packet interceptor system700decouples the interception of packets from the processing of those intercepted packets and provides a generic packet interception and pre-processing engine which can be utilized in parallel by multiple edge devices to implement their respective functionality/applications. As was noted above, the previous embodiments can alternatively process packets which are forwarded to them by the ISP's routing equipment. The edge adapter/packet interceptor system700provides this interception and forwarding service. Further, the system700provides a standardized interface to a network such as the Internet for the connection of edge type or packet intercepting devices making it easier for an ISP to offer the services/enhancements of many different providers. In addition, the system700is capable of processing packets at, or in excess, of wire speed so as not to degrade network performance from the optimal. In one embodiment, the system700is selectively transparent to the network. Where the device is to be visible, it can be addressed just like any other device coupled with the network. However, this addressability may be disabled to make the device invisible to other network devices.

The system700includes a router702and a packet interceptor adapter720coupled with the router. The router702is preferably located within an ISP located at the edge of a network100, preferably the Internet100as described above. Alternatively, the network100can be a private intranet or extranet as described above. Further, the network100may be an optical based network100or electrical, or combinations thereof. Exemplary routers702include: the Cisco 12000 Series GSR Internet router, manufactured by Cisco Systems, Inc., located in San Jose, Calif.; the Cisco 10000 Edge Services Router, manufactured by Cisco Systems, Inc., located in San Jose, Calif.; the Cisco 7500 Series router, manufactured by Cisco Systems, Inc., located in San Jose, Calif.; the Passport 8600 Routing Switch, manufactured by Nortel Networks, Inc., located in Saint John, Canada; the GRF MultiGigabit Router GRF 1600, manufactured by Lucent Technologies, Inc., located in Murray Hill, N.J.; and the M20, M40, and M160 Internet Backbone Routers, manufactured by Juniper Networks, Inc., located in Sunnyvale, Calif.

In the preferred embodiments, the adapter720, which preferably comprises an adapter card (also known as a “board” or “blade”) inserted into the router's702expansion slot backplane, is the Intelligent Packet Architecture™ adapter manufactured by CloudShield Technologies, Inc., located in San Jose, Calif. The adapter720is coupled with the router702so as to be able to intercept packets704before they are routed by the router702over the network100. In alternative embodiments, the adapter720may comprise a stand alone device either coupled with the router702or coupled in line with the router702on the network100. In the latter case, the adapter720is capable of interfacing with the network100, whether optical or electrical.

The router702further includes a network interface710, a routing table728and routing logic730. As is known, and described above, packets704enter the router702from the network100via the network interface710. In normal operation, where there is no edge adapter720installed, the packet704would be routed to the next network100node by the routing table728and routing logic730which analyze the destination internet protocol address of the packet704and determine where the packet704should be sent next within the network100. It will be appreciated that the routing logic730and routing table728can further implement policy based routing and quality of service protocols as are known in the art.

The logical architecture of the packet interceptor adapter720includes a packet analyzer712, a buffer714, a rules processor716and an external device interface718. The edge adapter720further includes a management interface722and interfaces734for external edge devices724. The packet analyzer712is coupled with the network interface710of the router702so as to be able to intercept packets704before they can be routed by the routing logic730and routing table728. Further, the adapter720includes an interface736with the routing table728and routing logic730of the router702to send packets to be routed. This arrangement logically places the edge adapter720between the network interface100and the routing table728and routing logic730. In alternative embodiments, the routing table728and routing logic730of the router702can be configured to automatically forward all incoming packets out to the edge adapter720first and then route packets received from the edge adapter720as normal over the network100.

As packets704enter the router702, they are temporarily diverted to the packet analyzer712which determines whether or not the packet is to be intercepted. This determination is made in conjunction with the rules processor716by analyzing the header data706and application data707contained with the packet704according to pre-defined rules contained within the rules processor. As will be described in more detail below, if it is determined that the packet704is not to be intercepted, it is released to the routing logic730of the router702for normal routing. If the packet704is to be intercepted, it is stored in the buffer714for further processing and analysis by the rules processor716and interceptor/analyzer712or one or more of the external devices724.

Interception and subsequent processing of packets704is based on the application of rules to any of the various layers of data contained with the packet704. As is known in the art, the Internet utilizes the Transport Control Protocol/Internet Protocol (“TCP/IP”) protocols to exchange information among connected clients and server computer systems. Further, it is known that the Internet supports several application protocols such as hypertext transfer protocol (“HTTP”) or file transfer protocol (“FTP”). The ability of the Internet to support different application uses is based the concept of protocol “layering”, also referred to as the layered protocol stack. Layering is the idea of designing several individual pieces of software, where each one performs one out of a set of functions, instead of designing one piece of software which performs all of the functions. Layering simplifies software development and reduces complexity.

In a layered software architecture, many different software components interface with one another to achieve the desired functionality, e.g. allowing a user to communicate over a network. A well known layered network software architecture has the following five layers:

The application layer or layer5comprises the particular application program that the user is running on their computer such as a web browser or a web server. The application layer can be thought of as interfacing between the transport layer and a sixth layer which is the end user. Users communicate with the application layer which in turn delivers/receives data to/from the transport layer. Many different applications can be operating at any given time. Particular applications are assigned port numbers or addresses which the transport layer uses to uniquely identify and communicate with the applications. Well known applications have fixed port addresses known as “well known ports.” These ports are assigned by the Internet Assigned Numbers Authority (IANA).

The transport layer, layer4, interfaces the user applications to the network infrastructure and structures the data for transmission by the routing layer. An exemplary transport layer is the Transport Control Protocol (“TCP”) described above. TCP is a connection oriented protocol requiring the establishment of parameters for transmission prior to the exchange of data. For more information on the TCP protocol, see TRANSMISSION CONTROL PROTOCOL, DARPA INTERNET PROGRAM, PROTOCOL SPECIFICATION, September 1981, prepared for Defense Advanced Research Projects Agency, Information Processing Techniques Office by Information Sciences Institute, University of Southern California. As described above, the transport layer interfaces with particular applications using a port number or address.

The routing layer, layer3, facilitates the delivery of data over the network and provides the logical network infrastructure which allows for network partitions or sub-networks, scalability, security and quality of service (“QoS”). An exemplary layer3protocol is the Internet Protocol (“IP”) discussed above. The IP layer3protocol relies on IP addresses to route and deliver packets from their source to their destination.

The switching layer, layer2, allows end station addressing and attachment. Layer2relies on unique Media Access Control (“MAC”) addresses assigned to each computer connected to the network. The interface layer, layer1, is responsible for device connectivity and usually refers to physical hardware/firmware which is used to build the physical network. Layers1and2are usually integrated and operate together. An exemplary layer1is provided by Ethernet type networks. Other layer1network hardware includes token ring or fiber optic based networks. The layer1physical network hardware provides a unique MAC address for use by layer2. For example, every Ethernet interface card includes a unique Ethernet address built into it.

The software which implements each layer only has to know how to interface with its adjacent layers, i.e. the application layer only has to know how to interact with the user and the transport layer. This, for example, alleviates the need for a web browser to know how to communicate over all of the various types of physical network hardware (layers1and2) that could be attached to the particular computer. For example, the web browser program, Internet Explorer™, manufactured by Microsoft Corporation, located in Redmond, Wash., does not need to know whether a user is connected to the Internet via local area network or a modem. The routing, switching and interface layers handle this.

In practice, the user communicates with the application layer which generates application data to be sent to a destination. For example, the user enters a Uniform Resource Locator (“URL”) into his web browser. The URL identifies a particular world wide web page to be retrieved from a particular web server computer. The web browser then generates a request to that web server for the desired web page, known as a “GET” request. This application data, in this case the URL and the request command, is passed to the transport layer. The transport layer breaks the data down into one or more packets which can be sent over the network. A packet is the unit of data which can be transferred over the network infrastructure and is discussed in more detail below. The transport layer figures out how many packets are needed, and organizes and identifies them so they can be reassembled at the destination. In the case of a URL, only one packet may be necessary to contain the data. The transport layer then passes each packet to the routing layer. The routing layer adds a source and destination address to each packet and hands the packet off to the switching layer. The switching layer in combination with the interface layer transmits the packet onto the network. Once on the network, network hardware such as routers and switches route and direct the packet to the proper destination based on the IP and MAC addresses.

At the destination, as each packet is received, the interface and switching layers pull them off the network hardware based on the MAC address and hand them up to the routing layer. The routing layer ensures that the particular packet has reached the right IP address and then passes the packet up to the transport layer. The transport layer receives and assembles all of the packets. If any packets are missing (due to a network error for example), the transport layer re-requests the missing packet from the source by generating a special request packet. Once the application data has been received and assembled, it is passed up to the application layer. For example, the destination may be a web server, within or external to the device, which receives the URL and request command for further processing.

Notice that the routing, switching and interface layers, as used with the IP protocol, implement a connectionless protocol. These three layers do not guarantee delivery of a packet or set of packets or guarantee how (i.e., over what route or in what order) or when those packets will arrive. They perform a specific function of attempting to deliver a given packet to its intended destination. It is up to the transport layer to make sure that the overall communication is successful.

Another layered architecture which defines seven different layers is the Open Systems Interconnect (“OSI”) model. These layers include the application layer, the presentation layer, the session layer, the transport layer, the network layer, the data-link layer and the physical later. For more information on layered network architectures, see Layer3Switching, An Introduction, 3-Com Technical Papers, published by 3-Com Corporation, Santa Clara, Calif.

As mentioned above, the transport layer breaks the application data down into packets. The routing layer then attempts to deliver each packet to its destination. A packet is the unit of data upon which the routing layer, layer3, operates. Packet switching is the scheme by which the packets are routed and delivered to their destination. A packet also logically comprises layers which correspond to the layers of the software architecture described above. In reality, each layer of the packet is really the pieces of information added by each of the software layers as the packet is passed along.

A packet can also logically be thought of as having two distinct layers or parts, the application data and the header data. The application data is the data provided by the application layer, layer5, as broken down by the transport layer, layer4, for transmission. This may also be referred to as the “payload”. This may be a URL, part of a web page, part of an email, part of a telnet terminal communications, part of a FTP file transfer, etc. The header layer comprises all of the other addressing information provided by layers1–4which is used to get the packet from its source application to its destination application. This includes the TCP port address (layer4), packet sequencing data (layer4), IP addresses of the source and destination computers (layer3) and the MAC address (layers2and1). While the above layering architecture and packet structure are preferred, one of ordinary skill in the art will appreciate that there are many different known network architectures and software models which can be used with the disclosed embodiments, such as the User Datagram Protocol (“UDP”) which is similar to TCP and transmits datagrams.

Packets are delivered to their destination over the network by routers and switches. These devices access the different layers within the packet to determine where to send the packet. A switch is usually associated with layer2. A switch reads the layer2, MAC address, from the packet and delivers the packet directly to the correct device. If the switch determines that the device with the correct MAC address is not connected to it, then the switch delivers the packet to another switch and so on until the packet is delivered to its intended destination.

A router is usually associated with layer3. A router reads the layer3IP address of the destination from the packet and, as described above, determines the route, and specifically the next adjacent network point to which the packet should be sent. Routers typically require routing logic which is programmed with knowledge of the network and knows how to determine the route over which to send a particular packet. This routing logic typically includes a routing table which identifies the routes for particular IP addresses. Many routers also factor in network usage information so as to route packets over less congested routes. A router ultimately delivers the packet to a switch which delivers the packet to its final destination. In some cases, a router and switch may be combined. A router may also be used as a firewall or proxy server (reverse or forward), blocking and/or re-routing packets based on their source and/or destination IP addresses.

Referring back toFIG. 7, all packets704which are flowing through the particular network node implemented by the router702first flow through the packet analyzer720. Each packet704is stored in the buffer714for processing by the rules processor716and packet analyzer720. The rules processor716contains one or more rule sets726which are used by the packet analyzer720. Each rule set726contains one or more rules732which are applied by the packet analyzer to the buffered packet704. Essentially, each rule732, described in more detail below, consists of a function and an action to be taken based on the results of the evaluation of the function. The function may involve analysis or examination of one or more portions of the packet704, and typically comprises a comparison operation which compares one or more portions of the packet704with one or more pre-defined values to determine whether or not the associated action should be taken. The packet analyzer720is capable of analyzing or examining any part of the packet704, including any data from the header data layer706or application data layer708(including all 5 or 7 layers as described above). For example, one rule732may be to compare the port address from the header data layer706to a value of 80 to determine if this is an HTTP packet. Further, the rule set726may contain several rules which compare different parts of the packet704to different values, in effect creating a compound function. An example would be to determine not only that a particular packet704is an HTTP packet but also to then determine the URL contained within the application data layer708. In addition, a function of a rule732may also use the result of another rule732in its rule set726or another rule set726as an input to be evaluated. In addition, state information representing the analysis of past packets may be stored and used by rules732to analyze future packets. This functionality, for example, may be used to monitor for sequences of particular packets704flowing over the network100.

Once the function of a rule732has been processed/evaluated, the packet analyzer720will take the desired course of action or actions as dictated by the rule732. The packer analyzer720is capable of taking several basic actions independently or in combination. Further, these actions may be implemented as part of a rule or separately implemented and triggered via an external command from the management interface722or from one or more of the external devices724. The basic actions that the packet analyzer720can take include: capturing a packet to the buffer714for further operation; releasing the buffered packet704to the routing logic730; forwarding a copy of the buffered packet704to one or more of the external devices724(described in more detail below); deleting the buffered packet704from the buffer714; modifying the buffered packet704; and replacing the buffered packet704with a new packet received from one of the external devices724. In addition to or alternatively instead of taking these basic actions, the packet analyzer720may log or otherwise store information about the packet, including storing a copy of the packet itself. This log may be used for subsequent processing/analysis of other packets or for reporting purposes. As can be seen, one or more of these basic actions can be combined with others to create compound actions to be taken on a given packet704. For example, a compound action could include capturing a given packet704which satisfied the operation of a particular rule732, forwarding a copy of the captured packet704to one of the external devices724for further processing, and in response to a command received from that external device724(as determined by its own processing of the copy of the packet704), modifying the IP address and payload of the captured packet704and releasing the modified packet704to the routing logic730of the router702. It will be appreciated that such complex actions and compound operations can be directly implemented as opposed to being implemented via a combination of basic actions.

In addition, data about the packet704may be stored in a memory for use by other rules, for processing the current or future packets704. This allows stateful processing, i.e. state based rules, of packets704as they flow through the packet analyzer720. By storing information about past packet704activity that the packet analyzer720has processed, rules732may be implemented which take into account historical packet activity. An additional basic operation of the packet analyzer720is provided for storing a one or more attributes, or an entire copy, of the captured packet in a state memory. For example, a rule732may defined to watch for multiple malformed packets704. Where a single malformed packet704is received, the rule732will take no action as this may be due to a random network error. However, data regarding that malformed packet, or the entire packet itself, will be stored. If another malformed packet704, similar to the first malformed packet704, is subsequently received, the rule732may determine that some malicious activity is underway and delete the second packet704. Other state information may also be recorded such as a time stamp. This allows the memory to be periodically purged, or alternatively, allows the rule732to take into account the frequency of occurrence, etc.

The packet analyzer720is fully programmable and rules732must be defined for each desired action and contingency. If no rules are defined for a particular contingency, the packet analyzer720will take the default action of releasing the packet. In this way, an unprogrammed device will not impede network traffic. For example, where a given packet704fails to trigger any rules732, that packet704can be automatically released to the routing logic730of the router702through the operation of a default action. In one embodiment, the default action is part of a default rule732, such as a rule732which has an evaluation function which always triggers the associated action. In this way, packets704, for which the packet analyzer720or no external device724wishes to intercept are simply released to the routing logic703for routing as normal. In an alternate embodiment, an unprogrammed packet analyzer720will take no action including not releasing the packet704.

Note that depending upon the implementation of the adapter720, the basic operations may be implemented in a different fashion. For example, if the packet analyzer720automatically captures every packet704which flows through the device720to the buffer714, then a capture packet operation may not be necessary. However, in this situation, a release packet operation is necessary to actively release unwanted packets704. In alternative embodiments, the packet analyzer720may implement an in-line filtering function which eliminates the need to capture a given packet704to the buffer714for initial analysis. In this case, a capture packet action is required to tell the packet analyzer720to capture the packet704to the buffer714for subsequent analysis and processing. Further, then, the packet analyzer720does not need to actively release unwanted packets704. However, a release packet action is still necessary to release those packets704which are captured to the buffer714.

As described above, the rules processor716may comprises multiple rule sets726and rules732. Some rule sets726and their rules732may be defined by the external devices724coupled with the edge/packet interception device720. For example, one external device724may want to intercept DNS packets and will define a rule set726to implement that function. Another external device may want to monitor and copy all HTTP requests to a particular IP address and will define a rule set726to implement that function. Other rules sets726may be standardized and provided as standard functions, such as in a library. Still other rule sets726may be defined by an external device724but can be entirely processed by the rules processor716. These rule sets726and rules732may be redefined or reset dynamically by the rules processor716or the external devices724, as needed, to implement their desired functionality. Further, the rule sets726and rules732may be re-defined or reset via the management interface722. Rule sets726may also implement security or authentication to prevent one external device724from interfering with the operation or security of another external device724. The rules processor716interfaces with the external devices724and the management interface to enable definition and modification/re-definition of rules732and rule sets726both statically and dynamically.

The external device interface718couples the adapter720with the external devices724. The interface718provides the hardware and software connection to pass data back and forth between the packet analyzer712and rules processor716and the external devices724. This data includes commands to the adapter720, such as to release a buffered packet704, modify a buffered packet704or to redefine one or more of the rules732or rule sets726in the rules processor716. In addition, the data includes packets to be delivered to the routing logic730of the router702for routing onto the network100, e.g. a packet to replace the packet in the buffer714and then be released to the routing logic730. Further the data can include copies of buffered packets704from the packet analyzer712sent to one or more of the external devices724in response to the action of one or more rules732. The interface718further implements the parallel connection of multiple external devices724to the network100so that each device724does not increase the overall network100latency. The interface718also implements arbitration schemes so that each external device724can implement its particular application in an efficient manner and without interference from the other external devices724. In the preferred embodiment, up to eight external devices may be coupled with the adapter720via the interface718, although alternative embodiments may support fewer or more devices. In one embodiment, all packet processing is handled within the adapter720and no external device interface718is provided.

Referring now toFIG. 8, there is shown a more detailed block diagram800of the adapter720fromFIG. 7. As described above, the adapter720is preferably implemented as an adapter card/board/blade which is inserted into a router's702backplane interface. Further, the adapter card comprises a management controller832and four adapter daughter cards802, each daughter card preferably providing two external device724interfaces836. Further, a bridge device820is provided to interface each of the daughter cards802with the management controller832and a router interface834which couples each of the daughter cards802with the router702backplane.

The management controller832preferably comprises an external interface838coupled with a processor842and memory840. The external interface838is preferably an 82559 100 megabit Ethernet interface, manufactured by Intel Corporation, located in Santa Clara, Calif. It will be appreciated that other external interface technologies may also be used such as serial, parallel, coaxial and fiber optic based interfaces. The external interface838further comprises a VMS747 Security/Cryptographic Processor, manufactured by Philips Semiconductors, Inc., located in the Netherlands for security. The external interface838interfaces the management controller832with an external management device (not shown) for controlling and managing the adapter720via interface846which is preferably a 100 megabit Ethernet interface. The external management device is preferably a 808x compatible desktop computer including a Pentium Class processor such as a Pentium III processor manufactured by Intel Corporation in Santa Clara, Calif., 32 megabytes of RAM, 6 gigabytes of hard disk space and an Ethernet interface. It will be appreciated that such desktop computer systems are well known. In alternative embodiments, the external management device can be locally or remotely located with respect to the adapter720. The processor842is preferably a StrongArm™ control processor manufactured by Intel Corporation located Santa Clara, Calif. The processor842is coupled with memory840which preferably comprises both 16 megabytes of Synchronous Dynamic Random Access Memory as working storage and 32 megabytes of non-volatile (Flash or Static RAM) storage for firmware and back-up storage. The processor742interfaces the management controller732with the four daughter cards802using a standard Personal Computer Interface (“PCI”) compliant bus844and bridge logic820. Alternatively, the Compact Personal Computer Interface (“CPCI”) may be used.

Each daughter card802includes a network processor804, bulk data storage806, an external device724interface controller808, a memory interface814, a classification co-processor810, non-volatile storage812, and a content addressable memory816. The network processor804is preferably an IXP 1200 Network Processor, manufactured by Intel Corporation, located in Santa Clara, Calif. The network processor804includes six micro-engines (not shown) which handle buffering and processing packets as will be described. The network processor804is coupled with the PCI bus830which interfaces the daughter card802with the PCI bridge logic820which in turn links all of the daughter cards802together and with the management controller832. The network processor is also coupled with the bulk data storage806, which is preferably 8 megabytes of Synchronous Dynamic Random Access Memory (SDRAM), via a 64 bit. 83 MHz bi-directional (166 MHz total) SDRAM bus. The bulk data storage806is used to store the operating software for the network processor804, the buffered packets undergoing processing as well as the rules and rule sets as will be described below.

The network processor804is further coupled with the external device724interface controller via a 64 bit. 66 MHz bi-directional (132 MHz total) IX bus826. The external device724interface controller is preferably an IXF 1002 Dual Port Gigabit Ethernet MAC, manufactured by Level One™, Inc., located in Sacramento, Calif., a subsidiary of Intel Corp., located in Santa Clara, Calif. The external device724interface controller interfaces with the external devices724using gigabit optical transceiver interfaces836.

In addition, the IX bus826also interconnects the four daughter cards802with the router backplane (not shown) via the router interface834. The interface834preferably comprises a Quad IXA field programmable gate array, manufactured by Xilinx located in San Jose, Calif., which controls cross communications between the daughter cards802and the traffic gating to the router backplane. Further, the router interface834further comprises the router switch fabric interface to interconnect the adapter720with the router backplane.

The classification co-processor810preferably comprises a ClassiPI™ Classification Co-processor, manufactured by SwitchON Networks, Inc., located in Milpitas, Calif. The non-volatile storage812preferably comprises 32 megabytes of Flash memory or Static RAM or other non-volatile storage as is known in the art. The content addressable memory816preferably comprises a NetLogic IPCAM® Ternary CAM Ternary Content Addressable Memory, manufactured by NetLogic Microsystems, Inc., located in Mountain View, Calif. The classification co-processor810, the non-volatile storage812and the content addressable memory816are all coupled with the memory interface814via memory busses818,820and822. The memory interface814is preferably a field programmable gate array device implementing glue logic and clocking signals for the non-volatile memory812. The memory interface814further couples the classification co-processor810, the non-volatile storage812and the content addressable memory816with the network processor804via a 32 bit 83 MHz bi-directional (166 MHz) Static RAM memory bus824.

The non-volatile memory812is used to store the operating software, including the operating system and custom microcode, for the adapter800. Upon boot up of the adapter800, this operating code is loaded into the bulk storage memory806from which it is executed. The non-volatile memory812is further used to store rules832and state level information used to restore previous system operation parameters when powering on. The classification co-processor810and content addressable memory816are used by the network processor804to offload specific rule processing tasks when it is more efficient to do so. In particular, processing of rules which involves table look ups or matching values to table entries is best handled by the content addressable memory816. Establishing packet type or other classifying operations are best handled by the classification co-processor810. As will be described below in more detail, the operating code of the network processor804is pre-programmed to cause the network processor804to offload certain processing functions to the classification co-processor810or the content addressable memory816when those devices can perform the particular function more quickly and efficiently than the network processor804can. It will be appreciated that other application or function specific processing devices may be included to more efficiently process particular functions of the adapter800. Such devices may include: a CryptoSwift™ cryptographic processor, manufactured by Rainbow Technologies Products, Inc. located in Irvine, Calif.; a C-5™ Digital Communications Processor, manufactured by C-Port, Inc., located in North Andover, Mass., a subsidiary of Motorola, Inc., located in Schaumburg, Ill.; a NetLogic Policy Co-Processor™ Packet Classification Engine, manufactured by NetLogic Microsystems, Inc., located in Mountain View, Calif.; a NetLogic CIDR Co-Processor™ Longest Prefix Match Engine, manufactured by NetLogic Microsystems, Inc., located in Mountain View, Calif.; a NetLogic IPCAM® Ternary CAM Ternary Content Addressable Memory, manufactured by NetLogic Microsystems, Inc., located in Mountain View, Calif.; a NetLogic SyncCAM® Binary CAM Binary Content Addressable Memory, manufactured by NetLogic Microsystems, Inc., located in Mountain View, Calif.; or a NetLogic NCAM™ Binary CAM Binary Content Addressable Memory, manufactured by NetLogic Microsystems, Inc., located in Mountain View, Calif.

It will be appreciated that the preferred components are known in the art and that suitable substitutes which implement the same functionality may be used. Further, the disclosed packet interceptor adapter may also be embodied in an alternative physical architecture such as a single board design, or an adapter box external to the router.

Generic operation of the packet interceptor adapter720is as follows: A packet is intercepted by the packet analyzer712/804. Framers on the router interface834capture the packet and forward it to the network processor804. Framers are protocol specific devices which understand the network protocol in use, such as Ethernet or Asynchronous Transfer Mode (“ATM”), and which are capable of isolating packets from the raw communications stream and extracting the actual packet contents.

The packet is buffered in buffer714/806. The network processor804places the intercepted packet into the bulk data storage806and creates and stores a packet information block (“PIB”) which contains parameters of the packet for efficient reference. These parameters include the source and destination addresses, length and other packet specific data as well as the address within the SDRAM806where the packet is buffered/stored. The network processor804further creates a pointer to the packet information block in a queue which lists packets ready for further processing. In one embodiment, the network processor804includes six micro-engines as described above. Two of these micro-engines are designated masters and the remaining four are designated as slaves. As packets enter the adapter800, one of the two master micro-engines, depending upon availability, buffers the packet to the SDRAM806and creates the PIB and pointer.

First level rules/sets are executed against the buffered packets. In one embodiment, the slave micro-engines, described above, when idle, continually check the queue of packets ready for further processing. When there is a pointer in the queue of a packet that is ready, the idle slave micro-engine dequeues the pointer entry for the packet and begins processing that packet according to the rules and rule sets programmed into the adapter800. In the preferred embodiment, each rule set consist of a hierarchical tree of nodes which are logically linked together, where one or more nodes form a rule. Each tree begins with a root entry node where processing begins. Each node may be one of three types, data gathering, decision or action. Data gathering nodes retrieve data or other information about the current packet, about the current operating environment or about other packets which may be relevant to the current packet being processed and which have been stored for such reference. Data gathering nodes gather information to be used by decision nodes. Decision nodes perform a function utilizing the data gathered by the data gathering nodes such as a comparison function, an equality function, an inequality function, or some other mathematical and/or Boolean operation. An action node uses the result of the decision node to perform some operation on the packet. In the preferred adapter800, the possible actions include releasing the current packet, copying the current packet and sending the copy to an external device via the external device interface808, or alternatively, sending the PIB or pointer, deleting the packet or modifying some or all of the packet and releasing it, or combination thereof. Each node specifies another node to which processing should continue when processing of the current node is complete. It will be appreciated that the node and tree structure is a logical data organization which may be implemented as a table of pointers or other construct as is known.

When processing a data gathering, decision or action node, the slave micro-engine may offload the processing to a co-processing element such as the classification co-processor810or the content addressable memory816. The operating code of the slave micro-engine is pre-programmed to cause the micro-engine offload processing of specific node functions when that processing can be more efficiently completed with the other device. In this case, while the co-processing device is processing the particular node, the slave micro-engine either waits for processing to complete or begins processing another packet. In the latter case, when the co-processing device finishes its processing of the particular node, it can indicate that the packet requires further processing, for example by adding a pointer back to the ready for processing queue, so that a slave micro-engine will finish processing the packet.

Once a slave micro-engine has begun processing a packet, it must determine which rule set to enact upon the packet. In one embodiment, each rule set defines a set of one or more packet parameters which indicate to the slave micro-engine that the rule set is to be applied to the current packet. The slave micro-engine references the packet information block using the pointer to determine that the one or more packet parameters meet the rule set requirements. If so, then the slave micro-engine executes that rule set starting with the root node in the tree. If a particular packet triggers application of more than one rule set, the slave micro-engine processes the rule sets in a prioritized order. Alternatively, other execution schemes may be used such as round robin. In one embodiment, the slave micro-engine determines which rule set to execute based upon packet type, wherein only a single rule set is stored for each type of packet that may be intercepted. For example, FTP packets may trigger application of one rule set while HTTP packets may trigger application of a second rule set.

Each rule set/tree of nodes then consists of a set of data gathering, decision and action nodes which process the packet and take a particular course of action. In one embodiment, each rule set is constructed so as to make a quick initial determination on whether to hold or release the packet from the buffer. In this way, processing latency is reduced. Once the particular course of action has been taken with the packet, the slave micro-engine other rule sets, if any, on that packet or returns to polling the queue of packets ready for processing to pick up another packet for processing.

When an action node results in sending a copy of a packet out to an external device, no further action is taken on that packet until a response is received from the external device. In one embodiment, the slave micro-engine waits for a response from that external device before continuing processing. In an alternate embodiment, the slave micro-engine processes other packets while waiting. The response from the external device instructs the slave micro-engine on what further actions to take with the packet. Such further action includes deleting the packet, releasing the packet, or modifying the packet, or combinations thereof. In one embodiment, the external device may provide a substitute packet for the buffered packet to release, with the buffered packet being deleted. This substitute packet may be provided directly to the buffer806to overwrite the buffered packet. In yet another alternative embodiment, once the copy of the packet, the PIB or the pointer has been sent to the external device, the slave micro-engine is free to begin processing another packet. The external device then signals that it has completed its processing, such as by writing a packet pointer to the queue of packets ready for processing or some other flag indicating the further processing can take place on the buffered packet to complete the processing thereof.

Where a particular packet fails to trigger the application of any of the rule sets, default rules or actions may be provided for processing the packet, as discussed above. In the preferred embodiment, the default rule/action consists only of the action of releasing the packet. In this way, packets which are not of interest are immediately released for normal routing.

In addition, the adapter800may receive commands from either one more of the external devices836, or the management interface832. In one embodiment, the adapter800authenticates any commands received to ensure they are from valid sources. Such commands include commands for adding, modifying or deleting a rule set, commands for providing an externally generated packet for release, or commands to delete, modify or release a packet currently in the buffer.

The specific operation of the packet interceptor adapter720executing denial of service protection application for malformed Internet Control Message Protocol (“ICMP”) packets is as follows: Framers on the router interface834captures a packet and forwards to network processor804. An idle master micro-engine on the Network processor804stores packet in buffer/SDRAM806and creates PIB and pointer. The pointer put on the queue of packets ready for processing. An idle slave micro-engine checks the queue for packets to be processes and dequeues the packet pointer. The slave micro-engine executes a default application specific rule set. The first rule in the set checks the source IP address of the packet against a list of blocked IP addresses. This processing takes place in the content addressable memory816which is more efficient at processing this type of look-up function.

If the source IP address matches a blocked IP address stored in the content addressable memory816, the slave micro-engine deletes the packet from the buffer and processing ends for this packet. If the source IP address does not match a blocked IP address, the slave micro-engine determines the packet type by analyzing the packet header. If this packet is not an ICMP packet, the packet is released.

If the packet is an ICMP packet, the packet is sent to the classification co-processor810to check for proper packet construction. The classification co-processor810compares the construction of the buffered packet against a reference stored in the non-volatile memory812.

If the packet is determined to be malformed, the slave micro-engine is instructed to delete the packet and processing ends for this packet. In one embodiment, the IP address of malformed packet is added to a block list. In an alternate embodiment, the IP address is added to the block list only after the number of malformed packets received from this IP address exceeds a particular threshold. In still another embodiment, the receipt of one or more malformed packets raises an alert to a user for manual intervention to add the source IP address to the block list.

It will be appreciated that any device which intercepts and processes packets can utilize the packet interceptor adapter720. For example, devices which utilize the transport layer or layer4data to route packets to their destination or redirect them to alternate destinations are known. These devices attempt to learn the type of application data being carried by the packet based on the transport layer port address. As described above, well know applications utilize “well known ports.” For example, HTTP data uses port80, Telnet use port23, FTP uses port21and domain name server requests use port53. This information can be used to redirect a particular packet to a server which can more optimally handle the packet. Utilizing the packet interceptor adapter720, such devices could define a rule to have the adapter intercept packets destined for a particular port number of a particular IP address. For those packets which are intercepted, the action taken could be to modify the destination IP address to an alternate destination and release the packet. This functionality could be completely implemented on the adapter720itself or the adapter720could forward copies of intercepted packets out to an external device which dynamically determines the modified IP destination address.

Another exemplary application of the packet interceptor adapter720is as web switch. A web switch is used to balance the load across multiple mirror servers at a particular web site. The adapter720is programmed with a rule to intercept packets directed to transport layer port80of the particular web site (based on the IP address). Knowing that these packets contain HTTP requests, the adapter can re-route the packet from an overloaded server to a server which has excess capacity, thereby balancing the load distribution. Again, this functionality can be implemented directly on the adapter720or in combination with an external device724which is monitoring and controlling the load distribution across the servers.

In one alternative embodiment, the adapter800provides no external interface836for external devices. In this embodiment, the adapter800intercepts packets and executes rule sets as described above. The rule sets may be developed and provided by third party developers for particular applications. The adapter then comprises a generic packet interceptor and processor.

In still another alternative embodiment, the adapter is configured as an application specific device with a defined rule set for implementing a specific application or set of applications. For example, the adapter is specifically configured to act as an anti-denial of service security device.

IX. The Fifth Embodiment

Meeting the universal demand for an Internet that is more robust, that is capable of sustaining its own growth and that can adapt to new technologies, requires the migration of the current network infrastructure to next generation networking technologies. This next generation data network is often referred to as the “Optical Internet.”

The shift to the Optical Internet has created a new set of challenges. Chief among these challenges is the need to manage an exponentially higher volume of network traffic at much higher rates of speed. In the U.S., the principal standard for optical networks is the American National Standards Institute (“ANSI”) standard for synchronous data transmission over optical media known as Synchronous Optical Network (“SONET”). The SONET standard actually comprises multiple standards for transmission rates up to 9.953 gigabits per second (“Gbps”) with the capability to go up to 20 Gbps. Each transmission rate standard is known as an Optical Carrier Level (“OC-X”). Exemplary optical carrier levels include OC-12 for communications at 622.08 Mbps, OC-48 for communications at 2.488 Gbps and OC-192 for communications at 10 Gbps. Today's microprocessors face a situation where they cannot support the pace of performance increases associated with the deployment of fiber-based network bandwidth of OC-48 and higher. Simply put, the move to fiber-optic networks has pushed the physical limits of microprocessors and the I/O bus beyond their current technical capabilities. The platform described herein is designed to address many issues associated with Optical Internet services that cannot be addressed by the current software based firewall servers.

FIG. 9shows an exemplary device900for intercepting and processing packets at wire speed from an optical based network100, such as the Internet, compatible with the OC-48 standard or faster. For a more detailed explanation of the operation of devices which intercept and process packets, refer to U.S. Patent Application entitled “EDGE ADAPTER APPARATUS AND METHOD”, which is captioned above. The exemplary device900may include the Rapid Intelligent Processing Platform manufactured by Cloudshield Technologies, Inc., located in San Jose, Calif. For clarity, some components of the device900are not shown.

The device900shown inFIG. 9is coupled with the network100(consisting of an upstream network portion100A and a downstream network portion100B) via a network connection910so as to be able to intercept and process packets communicated between the upstream network portion100A and the downstream network portion100B of the network100. Herein, the phrase “coupled with” is defined to mean directly connected to or indirectly connected through one or more intermediate components. Such intermediate components may include both hardware and software based components. In one embodiment, the network connection910is an optical network connection. In an alternate embodiment, the network connection910is an electrical network connection.

In one embodiment, not shown in the figure, the device900is configured as a rack-mount system comprising a chassis which provides power, cooling and a housing for the other components, as described below. The housing further includes a backplane into which the other components plug into and which interconnects those components. Such components may include interface components to couple external devices to add additional processing functionality.

The device900includes two primary processing elements904A,904B which intercept and process packets from the network100. One primary processing element904A is coupled with the upstream network100A and the other primary processing element904B is coupled with the downstream portion of the network100B via the network interface920. It will be appreciated that additional primary processing elements904A,904B may be provided depending on the topology, physical and logical arrangement of the network100and the coupling point of the device900. Further, the functionality of the processing elements904A,904B may be consolidated into a single processing element. In one embodiment, each primary processing element904A,904B includes a printed circuit board capable of being plugged into the backplane described above. For more detail on the operation of the primary processing elements, refer to U.S. Patent Application entitled “APPARATUS AND METHOD FOR INTERCONNECTING A PROCESSOR TO CO-PROCESSORS USING SHARED MEMORY”, captioned above.

The primary function of the primary processing elements904A,904B is to perform stateless processing tasks on the incoming packet stream. Stateless processing tasks are tasks that do not require knowledge of what has come before in the packet stream. Stateless tasks include ingress and egress filtering. Ingress and egress filtering involves ensuring that packets arriving from a particular portion of the network actually came from that portion of the network, as was described above. For example, where the device900is programmed with the range of network addresses in the portion of the network100B downstream of the device900, packets arriving from that downstream portion with a network address out of range would be detected as invalid and filtered out of the packet stream, or vice versa for the upstream portion of the network100A. Egress filtering refers to filtering in the upstream to downstream direction and ingress filtering refers to filtering in the downstream to upstream direction. For the filtering function, the filter values are typically maintained in block lists. Note that while filtering is a stateless function, independent of what packets have come before, the device900interjects stateful processing, as described below, to dynamically update the filtering or other information required for the stateless processing tasks. While the network processor906A,906B on the primary processing elements904A,904B can store state information about historical packet activity, each processing element904A,904B only sees one direction of the packet flow off the network100. Therefore, they cannot perform true stateful processing tasks which requires bi-directional visibility. This functionality is provided by the secondary processing elements912A,912B, described in more detail below.

The device900further includes two secondary processing elements912A,912B which are coupled with the primary processing elements904A,904B via a command/control bus924and packet busses926A,926B,926C,926D. In one embodiment, each secondary processing element912A,912B is a printed circuit board capable of being plugged into the backplane described above. Additional secondary processing elements912A,912B may be included or the functionality of the secondary processing elements912A,912B may be consolidated into a single secondary processing element. In one embodiment, the command/control bus924is a bus routed over the interconnecting backplane of device900and complying with the Compact Personal Computer Interface (“cPCI”) standard and is 64 bits wide and operates at a frequency of at least 33 MHz. Exemplary packet busses926A,926B,926C,926D include busses complying with the IX bus protocol of the Intel IXP1200 Network Processing Unit and are described in more detail below. Each exemplary packet bus926A,926B,926C,926D may be bi-directional, 64 bits wide and operate at a frequency of at least 84 MHz and may be routed over the backplane described above. Alternatively, other bus technologies/protocols may be used and are dependent upon the implementation of the device900. The command/control bus924carries command and control information between the primary and secondary processing elements904A,904B,912A,912B. The packet busses926A,926B,926C,926D carry packet data between the primary and secondary processing elements904A,904B,912A,912B. For more detail on the operation of the secondary processing elements, refer to U.S. Patent Application entitled “APPARATUS AND METHOD FOR INTERFACING WITH A HIGH SPEED BI-DIRECTIONAL NETWORK”, captioned above.

The primary function of the secondary processing elements912A,912B is to perform stateful processing tasks, i.e. tasks which are dependent on historical activity. One example of a stateful processing task involves network security applications which require monitoring conversations, i.e. bi-directional packet flow, in the packet stream, typically consisting of requests and responses to those requests. Stateful processing and the ability to monitor traffic bi-directionally allows the secondary processing elements watch for requests and responses and match them up. The arrangement of the inbound network processors906C of the secondary processing elements912A,912B, described in more detail below, allows them to share information about packets coming from either direction, i.e. upstream or downstream. Further, the secondary processing elements912A,912B can affect the stateless processing of the primary processing elements904A,904B. For example, where the secondary processing elements912A,912B determine that packets from a certain network address are consistently invalid, the secondary processing elements912A,912B can add that network address to the filtering list of the primary processing elements904A,904B thereby dynamically updating the stateless processing environment.

For example, packets such as those traversing between a web browser and web server change port numbers once a session between the two entities is created. A stateless rule cannot be applied that says “don't allow HTTP POST commands from network address ABC” without destroying all communications from the network address ABC. To accomplish the desired filtering and not destroy all communications from the source network address, the device900watches for new sessions directed to the web server on port80(standard HTTP application port). By watching the traffic, an example session might choose to then communicate on port23899at the web server. Only by subsequently watching traffic destined to this new port would the device900be able to search for HTTP POST commands that need to be blocked. Once identified, the packets could then be dealt with. If the session startup was not monitored and information not stored for future reference, i.e. not storing state information, an HTTP POST command traversing the network as part of a text stream from a different application, such as a document about how to configure a blocking system, might be falsely identified. Stateful inspection generally requires visibility to traffic in both directions. In the case above, a packet from the client to the server would have shown the request for a new web session. The response from the server to the client would have shown the web server port number to monitor. In firewalls it is also this response that subsequently allows that port number to have future traffic allowed through the firewall. This second port number on the server is the one for which traffic can be subsequently monitored for the HTTP POST. By storing relevant information for future packet processing analysis, the device900is made stateful.

In addition, the device900includes a management adapter914which is coupled with the command/control bus924. The management adapter914is used to manage the device900and control the functionality of the primary and secondary processing elements904A,904B,912A,912B. In one embodiment, the management adapter914includes a computer server having dual-Pentium III processors manufactured by Intel Corporation, located in Santa Clara, Calif., or suitable alternatives. The management adapter914further includes at least 64 MB of RAM and at least 10 GB of hard disk storage. The management adapter914is preferably implemented as a single board computer that plugs into the back plane, as described above, although more than one board as well as a stand alone personal computer may also be used. The management adapter914further includes an external management interface (not shown) which allows the connection of an external management device (not shown) for programming, controlling and maintaining the device900. In one embodiment, the external management interface includes a model 82550 100 megabit Ethernet Interface manufactured by Intel Corporation, located in Santa Clara, Calif. Other interfaces, such as serial, parallel, coaxial and optical based interfaces may also be used. In one embodiment, the external management device is a desktop computer such as the Deskpro Model ENS SFF P733 manufactured by Compaq Computer Corporation, located in Houston, Tex. Alternatively, any suitable Pentium™ class computer having suitable memory and hard disk space in addition to Ethernet or other form of network connectivity, may be used. Further, the external management device may be located locally with respect to the device900or remotely and connected to the device900via a local or wide area network.

The primary processing elements904A,904B are preferably capable of operating in parallel. The two primary processing elements904A,904B, are also referred to as Media Adapter Cards (“MAC”) or Media Blade Adapters (“MBA”). Each primary processing element904A,904B includes a network interface920, two network processors906A,906B, a set922A,922B of one or more co-processors908, a packet bus interface928A,928B, and a command/control bus interface916. The network interface920is coupled with the network100via the network connection910. In one embodiment, the network connection910is an optical network connection operating at a throughput of approximately 2.5 Gbps and a 1, 4 or 16 bit width. Each network processor906A,906B is coupled with the network interface920, in a parallel configuration, to receive packets from the network100. The network interface converts the protocol, bus width and frequency of the network connection910to the protocol, bus width and frequency of the network processors906A,906B. Further, the network interface920splits the incoming data stream between the network processors906A,906B, as described below. It will be appreciated that the disclosed embodiments can support any number of network processors906A,906B operating in parallel as described below, as the application demands. Further, each secondary processing element912A,912B is also coupled with network interface920of one of the primary processing elements904A,904B via packet busses126C,126D to transmit packets onto the network100, described in more detail below. The network interface920converts the protocol, frequency and bus width of the packet busses126C,126D from the secondary processing elements to the protocol, frequency and bus width of the network connection910. In addition, each network processor906A,906B is coupled with a set922A,922B of one or more co-processors908which is described in more detail below. Further, each network processor906A,906B is coupled with the command/control bus924via command/control interface busses930A,930B and the command/control bus interface916. In one embodiment, the command/control interface busses930A,930B are compliant with the Personal Computer Interface (“PCI”) standard and are 32 bits wide and operate at a frequency of at least 33 MHz. Further, the command/control bus interface916is a PCI to cPCI bus bridge for interfacing the busses930A,930B with the command/control cPCI bus924, described above. Both network processors906A,906B are also coupled with one of the secondary processing elements912A,912B via the packet bus interface928A,928B and the packet bus926A,926B.

Each secondary processing element912A,912B also includes two network processors906C,906D, in a serial configuration, and a command/control bus interface916. It will be appreciated that the disclosed embodiments can support any number of network processors906A,906B operating serially as described below, as the application demands. Each of the network processors906C,906D is coupled with the command/control bus924via the command/control interface busses930C,930D and the command/control bus interface916. In one embodiment, the command/control interfaces are at least 33 MHz 32 bit PCI compliant as described above and the command/control bus interface916is a PCI-to-cPCI bus bridge as described above. One of the network processors906C is coupled with both network processors906A,906B of one of the primary processing elements904A,904B via the packet bus926A,926C and packet bus interface928A,928B for receiving packet data from the primary processing elements904A,904B. The other of the network processors906D is coupled with the network interface920of the other of the primary processing elements904A,904B via the packet bus926B,926D for sending packet data to the network100, as described above. The secondary processing elements912A,912B are also referred to as Intelligent Packet Adapters (“IPA”).

Each secondary processing element912A,912B further includes a shared synchronous dynamic RAM (“SDRAM”) memory fabric918coupled between each of the network processors906C,906D to allow the network processors906C,906D to operate uni-directionally and move data from the inbound network processor906C to the outbound network processor906D. For more detail on the operation of this memory fabric918, refer to U.S. patent application entitled “APPARATUS AND METHOD FOR INTERFACING WITH A HIGH SPEED BI-DIRECTIONAL NETWORK”, captioned above.

In addition, one of the network processors906C, from each secondary processing element912A,912B is coupled with a set922C of co-processors908. It will be appreciated that the description below relating to the sharing of co-processors908sets922A,922B between the two network processors906A,906B of the primary processing element904A,904B are applicable to the arrangement of the co-processors908and the secondary processing elements912A,912B. In one embodiment of the secondary processing elements926A,926B, the network processors906C which are sharing the co-processors908of set922C are located on two different circuit boards (one for each element912A,912B) which share a common daughter card containing the set922C of co-processors908.

Each network processor906C,906D handles one direction of the bi-directional packet flow coming to/from the secondary processing elements912A,912B. In particular, the inbound network processor906C handles traffic incoming to the secondary processing element912A,912B and performs inspection and analysis tasks. The outbound network processor906D handles outgoing traffic from the secondary processing element912A,912B and performing actions on the packet such as modification, cleansing/deletion or insertion of new or replacement packets. By serializing the network processors906C,906D on the secondary processing elements912A,912B, the processing of packets can be divided into steps and distributed between the two network processors906C,906D. It will be appreciated more network processors906C,906D may be coupled serially to enhance the ability to sub-divide the processing task, lowering the burden on any one network processor906C,906D only at the cost of the latency added to the packet stream by the additional network processors906C,906D and the additional hardware cost. The network processors906C,906D intercommunicate and share data via an SDRAM memory fabric to implement this serial packet flow. For more detailed information, refer to U.S. Patent Application entitled “APPARATUS AND METHOD FOR INTERFACING WITH A HIGH SPEED BI-DIRECTIONAL NETWORK”, captioned above. Further each secondary processing element912A,912B handles a different direction of packet flow from the network100. In particular, the upstream secondary processing element912A handles packets flowing from the network100A upstream of the device900to the network100B downstream of the device900. The downstream secondary processing element912B handles packets flowing from the network100B downstream of the device900to the network100A upstream of the device900. For a more detailed description, please refer to U.S. Patent Application entitled “APPARATUS AND METHOD FOR INTERFACING WITH A HIGH SPEED BI-DIRECTIONAL NETWORK”, captioned above.

The device900intercepts and processes packets from the network100. One “upstream” primary processing element904A intercepts packets arriving from the network100A upstream of the device900and the other “downstream” primary processing element904B intercepts packets arriving from the network100B downstream of the device900. The intercepted packets are pre-processed, as described above, and then passed on to a corresponding secondary processing element912A,912B for subsequent processing and possible release back to the network100. Further, within each primary processing element904A,904B, the network interface920converts the protocol, frequency and bus width of the network connection910to the protocol, frequency an bus width of the network processors906A,906B and splits the incoming packet stream among the two network processors906A,906B which process packets in parallel (explained in more detail below). In one embodiment, the packet stream is alternated between the network processors906A,906B in a “ping-pong” fashion, i.e. a first packet going to one network processor906A,906B, the second packet going to the other network processor906A,906B and the next packet going back to the first network processor906A,906B, and so on. The network processors906A,906B are further coupled with the packet bus interface928A,928B which couples both network processors906A,906B with the common packet bus926A,926C to the secondary processing elements912A,912B. The packet bus interface928A,928B converts the bus width of the packet processors906A,906B to the bus width of the packet bus926A,926C. For more information about the packet bus interface928A,928B, refer to U.S. Patent Application entitled “APPARATUS AND METHOD FOR INTERCONNECTING A PROCESSOR TO CO-PROCESSORS USING SHARED MEMORY”, captioned above.

For example, a packet traveling from the network100A upstream of the device900to the network100B downstream of the device900is intercepted by the network interface920of the upstream primary processing element904A. The network interface920passes the intercepted packet to one of the network processors906A,906B which preliminarily process the packet as described above. This may involve the shared co-processors908, as described below. The packet is then transmitted to the inbound network processor906C of the upstream secondary processing element912A for subsequent processing via the packet bus interface928A and the packet bus926A. Within the upstream secondary processing element912A, the packet is processed and moved from the inbound network processor906C to the outbound network processor906D via the SDRAM memory fabric918. This processing may involve processing by the shared co-processors922. If it is determined that the packet is to be released, in original or modified form, the outbound network processor906D sends the packet to the network interface920of the downstream primary processing element904B via the packet bus926B. The network interface920of the downstream primary processing element904B then transmits the packet back onto the network100B.

For packets traveling from the network100B downstream of the device900to the network100A upstream of the device900, the packets are intercepted by the network interface920of the downstream primary processing element904B. The network interface920passes the intercepted packet to one of the network processors906A,906B which preliminarily process the packet as described above. This may involve the shared co-processors908, as described below. The packet is then transmitted to the inbound network processor906C of the downstream secondary processing element912B for subsequent processing via the packet bus interface928B and packet bus926C. Within the downstream secondary processing element912B, the packet is processed and moved from the inbound network processor906C to the outbound network processor906D via the SDRAM memory fabric918. This processing may involve processing by the shared co-processors922. If it is determined that the packet is to be released, in original or modified form, the outbound network processor906D sends the packet to the network interface920of the upstream primary processing element904A via the packet bus926D. The network interface920of the upstream primary processing element904A then transmits the packet back onto the network100A.

Overall, the device900intercepts packets flowing in an up or downstream direction, processes them and determines a course of action based on the application that the device900is implementing. Such actions include, for example, releasing the packet to the network100, modifying the packet and releasing it to the network100, deleting the packet, substituting a different packet for the intercepted packet, forwarding the packet to additional internal or external processing resources (not shown), logging/storing information about the packet, or combinations thereof. Applications include content delivery application or security applications such as for preventing unauthorized network access or preventing denial of service attacks.

The network processor906A,906B,906C,906D used in the primary and secondary processing elements904A,904B,912A,912B is preferably a general purpose network processor which is suitable for a wide variety of network applications. In one embodiment, each primary and secondary processing element904A,904B,912A,912B includes two network processors906A,906B,906C,906D and supporting hardware (not shown), as described above. An exemplary network processor906A,906B,906C,906D is the Intel IXP1200 Network Processor Unit, manufactured by Intel Corporation, located in Santa Clara, Calif. For more detailed information about the exemplary processor906, please refer to Intel® IXP1200 Network Processor Datasheet part no. 278298-007 published by Intel Corporation, located in Santa Clara, Calif. This exemplary network processor906A,906B provides six micro-engines/path-processors for performing processing tasks as well as a StrongARM™ control processor. Each of the network processors906A,906B,906C,906D preferably operates a frequency of 233 MHz or faster, although slower clock speeds may be used. It will be appreciated that other network specific or general purpose processors may be used.

As with most general purpose processors, the network processor906A,906B,906C,906D is capable of being programmed to perform a wide variety of tasks. Unfortunately, this adaptability typically comes at the price of performance at any one given task. Therefore, to assist with the processing of packets, each network processor906A,906B on the primary processing element904A,904B and the inbound network processor906C on the secondary processing element912A,912B is coupled with one or more co-processor908sets922A,922B,922C. The co-processors908on each set922A,922B,922C may be specialized processors which perform a more limited set of tasks, but perform them faster and more efficiently than the network processor906A,906B,906C is capable of. In one embodiment, the co-processors908include one or more classification co-processors and one or more content addressable memories (“CAM”).

The classification co-processors908are used to accelerate certain search and extraction rules for the network processor906A,906B,906C. In one embodiment of device900, the co-processor908set922A,922B of each primary processing element904A,904B includes two classification co-processors908. The shared co-processor908set922C also includes two classification co-processors shared by the secondary processing elements912A,912B. An exemplary classification co-processor is the PM2329 ClassiPI Network Classification Processor manufactured PMC-Sierra, Inc., located in Burnaby, BC Canada. This co-processor is capable of operating at a frequency of at least 100 MHz.

The CAM co-processors908are used to facilitate certain search and compare operations that would otherwise be computationally intensive and degrade the performance of the network processor906A,906B,906C. It is preferable that the CAM co-processors108be capable of being cascaded together, from 2 to 8, or more devices, to increase the search range. It is further preferable that the CAM co-processors108have the capability of processing at least 100 million compares per second. In such a design, each CAM data bit has an associated local mask bit that is used during the compare operation. In contrast with global mask bits, the local mask bits are used only with the associated bit and only for compare operations. This provides masking on an individual bit basis for ternary operation. In one embodiment of the device900, the co-processor908set922A,922B of each primary processing element904A,904B includes eight CAM co-processors908. The shared co-processor908set922C also includes eight CAM co-processors908shared by the secondary processing elements912A,912B. An exemplary CAM is the NetLogic NSE3128 Network Search Engine, formerly named IPCAM®-3, manufactured by NetLogic Microsystems, Inc., located in New York City, N.Y. For more detailed information about the exemplary CAM, refer to NSE3128 Network Search Engine product brief available at the web site netlogic.com/html/datasheets/nse3128.html, last accessed May 11, 2001.

An exemplary CAM device may have at least the following features:Organization options of any single device in cascade: 64K×72, 32K×144 or 16K×288;Local mask bit associated with each CAM;Clock rates: 50/66/100 MHz for 1 megabit devices or up to 200 MHz for a 9 megabit device;Eight global mask registers;16 bit instruction bus;32 bit result bus;36/72 bit comparand bi-directional bus or 72/144 bit comparand bus for a 9 megabit device;flags to indicate Match (“/M”), Multiple Match (“/MM”) and Full Flag (“/FF”); and24 bit Next Free Address (“NFA”) bus.

It will be appreciated that other classification processors and CAM's may be used and that additional task specific co-processors may also be used, such as cryptographic co-processors, to enhance the processing capability of the primary or secondary processing elements904A,904B,912A,912B.

As was discussed, the device900has to be able to operate at wire speed or faster so as not to degrade network throughput. In the case of an OC-48 class network, this means handling communications speeds of nearly 2.5 Gbps in both directions through the device900simultaneously to achieve full duplex functionality, for a total of nearly 5 Gbps throughput for the device900. Ideally, to achieve this goal, the co-processors908should be directly connected to the network processors906A,906B,906C. This would achieve the highest bandwidth of data exchange between these devices, maximizing their utilization and efficiency. Unfortunately, physical, electrical and device design limitations make this direct connection difficult to achieve.

With regard to the primary processing elements904A,904B, the physical limitations primarily include the limited amount of space/area available on a single circuit board. It is difficult and expensive to implement two network processors906A,906B, their supporting hardware and up to ten co-processors908, or more, as well as all of the routing interconnections on a single circuit board. An alternative is to move some of the devices to daughter card circuit boards which plug into a main circuit board. This would increase the available area for part placement but introduces electrical concerns regarding the interfaces between the devices. In particular, a daughter card arrangement introduces a board-to-board connector between the daughter card and the main circuit board. This connector introduces undesirable electrical characteristics into the interface between devices mounted on the daughter card and devices mounted on the main circuit board. These undesirable characteristics include increased noise, lower limits on operating frequency, increased parasitic capacitance, increased resistance and increased inductance. These characteristics limit the speed with which these devices can communicate. In order to properly interface across the connector, careful modeling is required to predict the electrical behavior of the connector and how it will impact the interface.

Further, complexities related to interfacing the network processors906A,906B to the co-processors908also complicate the design and implementation of the device900. In particular, both the network processor906A,906B and the co-processors908provide input/output busses for the purpose of interconnecting that device with other devices. However, the network processor906A,906B as well as the different types of co-processors908, all have different interface requirements, such as different supported clock frequencies, bus widths and communications protocols. In addition, the interfaces are further complicated by the desire to connect more than one of each type of co-processor908with the network processor906A,906B. Even further complicating the interface requirements is the desire to allow each network processor906A,906B on the processing element904to share the same co-processors908and allow each inbound network processor906C to share the same co-processor908set922C. Sharing co-processor908sets922A,922B,922C allows the network processors906A,906B,906C to interoperate and share data, such as state information, in addition to saving costs by reducing the number of devices on the primary processing elements904A,904B. When one network processor906A,906B,906C decides to store state information, that information is made available to the other network processor906A,906B,906C. Further, when global updates to the data stored within the co-processors908are needed, such as updates to the CAM tables, these updates can be performed more efficiently since there are fewer co-processor sets922A,922B,922C to update. For example, when the secondary processing elements926A,926B, due to the result of some stateful processing task, need to update the state information in the CAM data, such as the filtering block lists, the updates need to go to fewer devices resulting in a faster and more efficient distribution of those updates. Further, the sharing of state information among the network processors906A,906B on the primary processing elements904A,904B, allows the network processors906A,906B to operate in parallel and thereby reduces the traffic flow to each network processor906A,906B, achieving a longer number of clock cycles over which a packet may be processed.

For more detail on the operation of this co-processor90sharing and the interface between the primary and secondary network elements904A,904B,912A,912B and the co-processor sets922A,922B,922C, refer to U.S. Patent Application entitled “APPARATUS AND METHOD FOR INTERCONNECTING A PROCESSOR TO CO-PROCESSORS USING SHARED MEMORY”, captioned above.

In addition, the architecture of the device900allows for efficient processing of any portion of the packet regardless of whether it is in the header or payload. This allows for more flexible packet analysis which can adapt to changing network protocols. For example, packet changes such as Multi-protocol Label Switching (“MPLS”) have made even the normal IP header look different in a packet since it is now preceded by the MPLS tag. Similarly, new network application are constantly being developed may have their own format and header/payload structure. The disclosed architecture does not treat the header any different from payload in its ability to analyze a given packet. This allows for maximum adaptability to evolving network technologies.

As can be see, the above description discloses a unique architecture capable of bridging the technology gap between existing network processing technology and next generation networking technology. The architecture of the device900leverages parallel processing for stateless tasks and serialized/staged processing for stateful tasks. It will be appreciated that the ability to process data statefully requires bi-directional visibility over the traffic stream of the network102and further requires deployment of the device900at a point, i.e. a choke point, within the network102where all traffic of interest is visible and through which it must flow. Alternatively, the device900can provide partial stateful and stateless operation in situations where complete bi-directional visibility cannot be guaranteed or is not available.

For stateless processing tasks, such as filtering, pre-processing and other tasks not requiring knowledge of historical packet activity or matching of bi-directional packet activity, multiple parallel network processors906A,906B are provided for each network102A,102B direction of the bi-directional traffic stream. The incoming packets are equally distributed among the parallel network processors906A,906B, which reduces the load on any one processor. As described above, the primary processing elements904A,904B provide two network processors906A,906B each, operating parallel. Further, the architecture is scalable, allowing for additional parallel network processors906A,906B to be added to provide additional processing capability, with only the cost of the additional hardware required. The architecture of the device900further allows for the parallel network processors906A,906B to share a common set922A,922B of co-processors108. In addition to hardware savings, this configuration permits the processors906A,906B to share state information among themselves, further increasing efficiency of operation.

Where a particular application requires stateful processing tasks, such as a security application that needs to monitor bi-directional and/or historical packet activity, the architecture of the device900further provides serialized/staged processors for each direction of the packet flow. These serialized/staged processors divide up the required processing tasks, thereby reducing the load on any one processor. For each direction, a the packet data flows through an inbound processor906C dedicated to receiving inbound traffic and performing inspection, analysis and other preliminary tasks. The inbound processor then passes the packet data to an outbound processor via a memory fabric, described above. The outbound processor then completes the processing, such as by modifying, deleting, or releasing the packet modified or unmodified and or logging/storing information about the packet for subsequent processing. It will be appreciated that the architecture is scalable and that additional network processors906C,906D may be added to further divide up the processing burden, reducing the load on individual network processors906C,906D. Additional network processors906C,906D may be connected using the described memory fabric or by coupling multiple secondary processing elements912A,912B in series via the IX bus and backplane described above. Further, the inbound processors of each direction of packet flow are coupled together via a common set922C of co-processors similar to the parallel configured processors906A,906B. In addition to the hardware savings, this configuration permits the efficient sharing of bi-directional packet activity, thereby providing complete stateful processing capability of the bi-directional packet flow. Further, the network processors906C,906D performing the stateful processing can dynamically update state information to the stateless network processors906A,906B, thereby providing dynamic accommodation to changing network conditions.

The architecture of the device900bridges the network and packet processing technology gap by distributing the processing tasks and reducing the load and utilization of any one network processor906A,906B,906C,906D. For example, Network Processing Units (NPUs) such as the Intel® IXP1200, described above, were originally designed to be “systems on a chip” that performed all of the required processing tasks. They provide data buses, memory buses (SDRAM and SRAM) as well as interface buses (general purpose IO and PCI). Additionally they have multiple fast path processors, often called micro-engines, and control processors often embedded or attached via a control processor interface. In the case of the Intel IXP1200 a StrongARM control processor is embedded. These chips expect that data flows in from the data bus, is processed immediately or stored in SDRAM or SRAM memory for further processing. At the time of forwarding of the data, the data is read from the memory and forwarded out on the data bus. This methodology infers that data must traverse the data and memory buses at least twice, once to store and once to forward a packet.

The architecture of the device900sends packets on a data bus only once and traverse the memory bus at most twice versus a possible three times in the prior design. With regards to the memory bus the packet is written and only the portions of the packet required for inspection which were not processed as they flow through the processor need be read. This results in a 1 to 2 times flow rate utilization of the memory bus. Forwarding is handled invisibly to the processor, via the memory fabric, and thus removes that third traditional movement of the data across the memory bus.

The single direction of traffic flow through the device900allows network processors906A,906B,906C,906D to be able to process data flows faster than originally intended. This is due to the fact that most processors are constrained by bus saturation. Take the IXP1200 for example, the SDRAM bus is a 6.6 Gbps bus with saturation around 5 Gbps. The IX Bus (data bus) is a 6 Gbps bus with saturation around 4.1 Gbps. To understand traffic levels that can be achieved one should take the worst case traffic flow, which is generally small packets at highest flow rate, to calculate what can be processed. The SDRAM would limit a traditional environment to 1.66 Gbps and the IX Bus would limit at 2 Gbps. These are maximums and headroom should be preserved. This estimate would suggest that Gigabit Ethernet would be the most an IXP1200 could attain. By using the network processor906A,906B,906C,906D uni-directionally, OC-48 requires only 2.5 Gbps on the data bus and no more that 5 Gbps on the memory bus. This allows existing devices to process faster than originally intended. Additionally, since the packets are moved around less, no processor is required to forward the packets which frees up more internal micro-engines for processing the packet.

This same approach can utilize the newer network processors906A,906B,906C,906D being developed to handle OC-48 and faster networks to be able to process packets at speeds up to OC-192 (10 Gbps) and faster. This can be done with external memory versus internal memory. This is a significant issue since internal memory requires a far more complex design of a network processor, increasing design time, reducing yields and increasing costs.

As can be seen, the preferred packet interception device implements scalable, transparent and non-invasive interception of packets for multiple devices. It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.