Abstract:
A network gateway element is provided. The network gateway element appears as a single node to the external world, while it physically is maintained in at least two chassis. A routing node handles functions typically associated with routers, while another network element, such as a server, may handle functions typically associated with the server. The routing node may load-balance the traffic directed at the server. Additionally, the routing node may process packets for the server without the server having to become involved.

Description:
FIELD OF THE INVENTION 
     The present invention relates to IP networks, and more particularly to IP gateways, routers, and servers. 
     BACKGROUND OF THE INVENTION 
     Generally, routers, servers, and host computers may be found within an IP network. An Internet host computer within an IP network may be defined as the end consumer of communication services. A host generally executes application programs on behalf of users employing network communication functions in support of this function. The host is coupled to routers and servers within the typical IP network. 
     A router implementation of an IP stack that is used within a network gateway can be defined in the following way. An Internet gateway is a network device that is connected to two or more networks that appears to each of the networks as a connected host. The Internet gateway has one or more physical interfaces and IP address(es) on each of the networks to which it is connected. When forwarding a packet, the gateway chooses the next-hop gateway or the final hop for the destination host. This choice, referred to as routing, depends upon a routing table within the gateway. 
     The currently defined RFCs follow the model in which the user layer forwarding plane and the applications reside in the same physical chasses. This makes it difficult when the entities are separated across different physical chasses. 
     What is needed is a way for the different physical chasses to be treated as a single network element. 
     SUMMARY OF THE INVENTION 
     The present invention is directed at addressing the above-mentioned shortcomings, disadvantages and problems, and will be understood by reading and studying the following specification. 
     According to one aspect of the invention, a network gateway element appears as a single node to the external world, while it may be physically maintained in at least two chassis. 
     According to another aspect of the invention, routing node within one chassis handles functions typically associated with routers, while another network element, such as a server, maintained within another chassis may handle functions typically associated with the server. The routing node may load-balance the traffic directed at the server. Additionally, the routing node may process some of the packets for the server without the server having to become involved. 
     According to another aspect of the invention, the apparatus, system, and method work with established communication principles of the Internet protocol. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an exemplary IP network in which the invention may operate; 
         FIG. 2  shows a schematic diagram that illustrates an exemplary system overview in which local area networks and a wide area network are interconnected by routers and network gateway elements; 
         FIG. 3  illustrates an overview block diagram of a network gateway element; and 
         FIGS. 4 and 5  show a process for a network gateway element process; in accordance with aspects of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the following detailed description of exemplary embodiments of the invention, reference is made to the accompanied drawings, which form a part hereof, and which is shown by way of illustration, specific exemplary embodiments of which the invention may be practiced. Each embodiment is described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims. 
     Throughout the specification and claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise. The term “node” refers to a network element, such as a router. The term “flow” means a flow of packets. The term “user” refers to any person or customer such as a business or organization that employs a node to communicate or access resources over a network. The term “operator” refers to any technician or organization that maintains or services an IP based network. The term “IP” refers to Internet Protocol. The term “ICMP” refers to Internet Control Message Protocol. The term “DNS” refers to Domain Name Service. The term “IPC” refers to Inter-Process Communication. Referring to the drawings, like numbers indicate like parts throughout the views. Additionally, a reference to the singular includes a reference to the plural unless otherwise stated or is inconsistent with the disclosure herein. 
     Briefly described, the present invention is directed at providing a multi-chassis network node that is represented as a single network node to the rest of the network. 
     Illustrative Operating Environment 
     With reference to  FIG. 1 , an exemplary network in which the invention may operate is illustrated. As shown in the figure, network  100  includes mobile node (MN)  105 , radio access network (RAN)  110 , SGSN  115 , core network  120 , routers  125   A-F , network gateway elements  300   A-B , GGSNs  135   A-B , data network  140 , and data network  145 . 
     The connections and operation for IP network  100  will now be described. MN  105  is coupled to radio access network (RAN)  110 . Generally, MN  105  may include any device capable of connecting to a wireless network such as radio access network  110 . Such devices include cellular telephones, smart phones, handheld computers, personal computers, and the like. 
     Radio Access Network (RAN)  110  manages the radio resources and provides the user with a mechanism to access core network  120 . Radio access network  110  transports information to and from devices capable of wireless communication, such as MN  105 . Radio access network  110  may include both wireless and wired components. As shown in the figure, RAN  110  includes routers  125   A-C . A network node, or nodes, may be used to provide Quality of Service (QoS) rules relating to how packets are processed. 
     Core network  120  is an IP packet based backbone network that includes routers, such as routers  125   D-F , to connect the support nodes in the network. Routers are intermediary devices on a communications network that expedite message delivery. On a single network linking many computers through a mesh of possible connections, a router receives transmitted messages and forwards them to their correct destinations over available routes. A router may be a computer including memory, processors, and network interface units. 
     Some nodes may be General Packet Radio Service (GPRS) nodes. For example, Serving GPRS Support Node (SGSN)  115  may send and receive data from mobile nodes, such as MN  105 , over RAN  110 . SGSN  115  also maintains location information relating to MN  105 . SGSN  115  communicates between MN  105  and Gateway GPRS Support Node (GGSN)s  135   A-B  through core network  120 . 
     GGSNs  135   A-B  are coupled to core network  120  through routers  125   A-C  and act as wireless-gateways to data networks, such as network  140  and network  145 . Networks  140  and  145  may be the public Internet or a private data network. GGSNs  135   A-B  allow MN  105  to access network  140  and network  145 . 
     A network gateway element ( 300   A ) is coupled to the RAN and a network gateway element ( 300   B ) is coupled to the core network. Network gateway elements may be coupled to any network. Briefly described, network gateway elements  300   A-B  are located within at least two physical chassis. According to one embodiment of the invention, network gateway elements  300   A-B  consists of a server within one chassis and a router located within another chassis. While the network gateway elements are shown as a single network node, in actuality, the network gateway elements are contained in at least two chassis. Network gateway elements  300   A-B  are shown as a single network node as that is how it is viewed by the rest of the network nodes, such as the routers illustrated. 
     Furthermore, computers, and other related electronic devices may be connected to network  140  and network  145 . The public Internet itself may be formed from a vast number of such interconnected networks, computers, and routers. Network  100  may include many more components than those shown in  FIG. 1 . However, the components shown are sufficient to disclose an illustrative embodiment for practicing the present invention. 
       FIG. 2  shows another exemplary system in which the invention operates in which a number of local area networks (“LANs”)  220   a-d  and wide area network (“WAN”)  230  interconnected by routers  210  and network gateway elements ( 300 ). On an interconnected set of LANs—including those based on differing architectures and protocols—, a router acts as a link between LANs, enabling messages to be sent from one to another. 
     Communication links within LANs typically include twisted wire pair, fiber optics, or coaxial cable, while communication links between networks may utilize analog telephone lines, full or fractional dedicated digital lines including T1, T2, T3, and T4, Integrated Services Digital Networks (ISDNs), Digital Subscriber Lines (DSLs), Gigabit-ethernet links, Packet-Over-Sonet (PoS) links, wireless links, or other communications links. Furthermore, computers, such as remote computer  240 , and other related electronic devices can be remotely connected to either LANs  220   a-d  or WAN  230  via a modem and temporary telephone link. The number of WANs, LANs, and routers in  FIG. 2  may be increased or decreased without departing from the spirit or scope of this invention. As such, the Internet itself may be formed from a vast number of such interconnected networks, computers, and routers and that an embodiment of the invention could be practiced over the Internet without departing from the spirit and scope of the invention. 
       FIG. 3  illustrates a network gateway element ( 300 ) in accordance with aspects of the invention. As shown in the figure, network gateway element  300  includes router  302  and server  304 . Router  302  includes IP layer  306 , layer-2  308 , interfaces  310 , (Internet Control Message Protocol) ICMP for interfaces  316  and (Inter-Process Communication) IPC  318 . Interfaces  310  include router interfaces  312  and server interfaces  314 . Server  304  includes application  330 , layer-4  332 , IP layer  334  and IPC  336 . 
     Router  302  and server  304  are located within different physical chassis. The present architecture provides many advantages when the IP-interfaces and the IP-applications are not co-located within the same chassis. When the current network gateway element architecture is used, router  302  and server  304  appear as a single network node to a network. Router  302  and server  304  share the same IP Address thereby providing a single network-element image to the external world. 
     Network gateway element  300  acts as both a host and a gateway. It acts as a “host” since it is the ultimate consumer of the communication services and it executes application programs on behalf of users. It also acts as a “gateway” since it uses the routers capabilities for employing network and/or Internet communication services. Operation of network gateway element  300  will now be described in more detail. 
     Handling of a received packet by network gateway element  300  will be described first. When a packet arrives at network gateway element  300 , router  302  inspects the received packet to determine the action to perform on the packet. The received packet is received at interface  310 , and handled by layer-2  308  and IP layer  306 . Some packets that are intended for server  304  may be handled by router  302  without server  304  ever receiving the packet. For example, ICMP packets may be processed on router  302  on behalf of server  304 . Generally, router  302  will handle functions that it may perform more efficiently than server  304 . Similarly, server  304  will handle functions that it may perform more efficiently than router  302 . In this way, router  302  helps in preventing server  304  from incurring a heavy demand for packet-processing. When the received packet is destined for an application on server  304 , such as application  330 , the packet is sent to server  304  using IPC  318 . To determine whether a packet is destined for server  304  the flows programmed in router  302  are checked. 
     For packets handled by server  304 , IPC  336  receives the packet and forwards the packet to layer-4  332  through IP layer  334 . Layer-4 processes the packet and delivers the packet to application  330 . Application  330  may then use the packet. 
     Packet transmission from the server will now be described in more detail. Application  330  generates a packet. Layer-4 processes the packet. IP  332  then processes the packet, including preparing the IP header for the packet. The packet is then sent to IPC  318  on router  302  through the servers IPC ( 336 ). Router&#39;s IP  306 , and layer-2  308 , processes the packet and forwards the packet to interfaces  310 . According to one embodiment of the invention, the generated packet is forwarded to server interface  314 . The packet is then sent to a coupled network. The router and server interfaces may be located within the same “physical” interface. 
     An advantage of the network gateway element is that the IP interfaces, and IP addresses of the network gateway element are co-owned by the server and the router. Another advantage is that the traffic relating to the server may be load-balanced by the router using its own information and configuration (e.g. DNS) that is transparent to the server. Multiple network elements may be presented to the external world as a single node. 
       FIG. 4  illustrates a process for a server generating a packet to be sent out on a network, in accordance with aspects of the invention. After a start block, the process flows to block  410  where a packet is generated. Moving to block  420 , the packet is processed by Layer-4. Transitioning to block  430 , the packet is processed at the IP level. Flowing to block  440 , the packet is sent to the routing element using the server&#39;s IPC. The router receives the packet (block  450 ), processes the packet (block  460 ) and sends the packet to the external network (block  470 ). 
       FIG. 5  illustrates a process for receiving a packet at a network gateway element, in accordance with aspects of the invention. After a start block, the process flows to block  510  where a packet is received. Moving to block  520 , the packet is inspected. The inspection determines the actions to perform on the packet. Transitioning to block  530  the packet is processed based on the inspection. When the inspection determines that the packet may be more efficiently handled by the routing device, then the processing relating to the packet is performed by the routing device. Otherwise, the process flows to block  540  where the packet that is destined for the server, or layer-4 device, is sent to the server. Flowing to block  550 , the server receives and processes the packet. The process then returns to processing other actions. 
     The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.