Abstract:
A data communications network with a plurality of PoPs maintains a local database associated with each PoP and a central database somewhere on the data communications network. The local database contains a group identification such as a domain identification corresponding to a group of users, a maximum number of proxied sessions to provide the group of users at the PoP and a dynamic proxy session count corresponding to active proxied sessions currently provided to the group of users at the PoP. The central database contains a maximum number of proxied sessions to provide the group of users over the entire data communications network and a dynamic network-wide proxy session count corresponding to active proxied sessions currently provided to the group of users on the entire data communications network. Actions are taken when the group attempts to exceed either the local maximum number of sessions or the network-wide maximum number of sessions by more than a predetermined number. The actions may include assessing extra charges, denying access, and sending warning messages to appropriate recipients.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of Ser. No. 09/306,691, entitled “PROXY SESSION COUNT LIMITATION” by Aravind Sitaraman, Charles Yager and Craig Alesso filed on May 6, 1999 now U.S. Pat. No. 6,529,955. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the field of data communications networks. More particularly, this invention relates to a method and apparatus for limiting the number of proxied sessions provided to a group of users locally and network-wide in a data communications network. 
     2. The Background 
     ISPs (Internet Service Providers) and Telcos (telephone companies) (collectively referred to as “Wholesale Providers” or “Wholesalers”) typically offer wholesale Internet access and retail Internet access to their subscribers. Wholesale access is typically offered to subsidiary and specialized service providers, CLECs (Competitive Local Exchange Carriers), corporations, and Community of Interest (COI) providers. Naturally, the,processing afforded customers of the wholesale variety differs from the processing afforded customers of the retail variety. Subscriber information for individual wholesale users is usually stored by those who lease data communications network access from the Wholesaler. Hence, corporations, CLECs and COI providers do not normally share their user information with the wholesale providers. The Wholesaler, however, typically also has its own retail subscribers whose user information is stored in its databases. In some cases, a particular user might have accounts with both a retail and wholesale provider. Hence, the Wholesaler must distinguish between the user&#39;s wholesale and retail accounts and initiate different actions based upon their status or Service Level Agreements (SLAs). 
     See, for example, FIG. 1 where a pure retail environment has a number of network access servers (NAS 1 , NAS 2  and NAS 3 ) which provide data communications portals to the Wholesaler&#39;s point of presence (PoP) on the data communications network. Each NAS is in communication with a conventional AAA (authentication, authorization and accounting) service maintained by the Wholesaler. Incoming users connect to the NASes by dialing in over the telephone network or in another conventional manner such as via DSL (digital subscriber line) access, cable, ISDN (integrated services digital network), etc. 
     Traditional wholesale ISPs and Roaming Service Providers offer network access through a technique called “authentication proxying.” Proxying involves the transfer of the authentication responsibility to the “owner” of the subscriber. Thus, if a corporation was to outsource its corporate intranet to a Wholesaler, it would give up the maintenance of its dial-up servers (i.e., the NASes). It would not, however, normally want to give up the control of or information regarding its employees. Hence, when a corporate user connects to such a Wholesaler&#39;s network access servers, the user essentially perceives that the user is dialing into a corporate facility when the user is actually dialing into the Wholesaler&#39;s domain and then somehow gaining admittance to the corporation&#39;s intranet. 
     What really happens m that scenario is that the Wholesaler determines that the user belongs to Corporation A (Corp A ) by parsing either the fully qualified domain name (“FQDN”) (e.g., Joe@corpa.com) supplied by the user, reading the DNIS ID associated with the call, reading the CLID associated with the call, or by using some other known mechanism. Using a DNIS ID, the Wholesaler looks at the telephone number (or a specific NAS in access networks other than dial-up) through which the user is connecting to the network. So if a user calls in to 123-456-7890 from his number of 123-444-5555, then the Wholesaler can know which number was called, i.e., the completing station. Having determined that the user trying to gain access belongs to Corp A , the. Wholesaler cannot authenticate the user by itself. As noted earlier, the user&#39;s record is still located on Corp A &#39;s equipment. Hence, the Wholesaler will “proxy” out the authentication transaction from its AAA proxy service to Corp A . An AAA service within the corporation domain then identifies the user, verifies the password, and provisions the user with appropriate authorizations. It may also receive accounting information, if desired. Then the AAA service at Corp A  notifies the Wholesaler&#39;s proxy service that the user is acceptable and passes along provisioning details associated with the user (such as an IP (Internet protocol) address to use or a pool identification of an IP address pool from which an IP address needs to be allocated and any other information that may be needed). The Wholesaler then grants the user access to the network based upon the reply it gets back from Corp A . This technique is called “proxying.” This is shown diagrammatically in FIG.  2 . 
     To be able to perform basic proxying, the Wholesaler maintains minimal information on its proxy service  14  at its PoP. Information such as supported domain names, the IP address to which the transaction is to be sent, the port number (typically an OSI Layer 4 port number) to which the transaction is to be addressed, a shared secret between the proxy service and the remote AAA service, etc., are typically stored. 
     For example, turning now to FIG. 2, user Joe@corpa.com dials in to NAS 1 . A PPP (point to point protocol) session  10  is typically raised between Joe&#39;s terminal and NAS 1 . A LCP (Link Control Protocol) session is raised between NAS 1  and Joe&#39;s terminal. At this time the NAS 1  generates an authentication request using a protocol such as RADIUS (Remote Authentication Dial-In User Service) to the Wholesaler&#39;s proxy service  14 . Proxy service  14  then consults its local configuration database  16 . Proxy service  14  then makes a determination about where to send the authentication request (Access-Request in RADIUS). At this time the proxy service decides to forward the authentication request to the AAA service  18  maintained in the Corp A  domain  20 . The Corp A  AAA  18  then consults its local database  22  and authenticates Joe@corpa.com. Corp A  AAA  18  then returns an access-accept packet to proxy service  14  which, in turn, sends an access-accept packet to NAS 1 . Then an IPCP (Internet Protocol Control Protocol) session is raised between NAS 1  and Joe&#39;s terminal during which an IP address is returned to configure Joe&#39;s terminal&#39;s PPP stack completing the log-in of Joe@corpa.com. 
     Frequently a large corporation or similar entity will have a need to provide PoPs at a number of locations to service its clients, customers and/or employees in a number of different cities. For example, a corporation “Corp A ” located in Los Angeles, Calif. might have some employees using dial-up lines from San Francisco, Calif. and New York City, N.Y. It could let them dial directly to a server in Los Angeles, but the telephone network charges might be relatively high for the long distance connection. Alternatively, Corp A  could establish PoPs in these cities—but the cost is also usually relatively high. Instead, it would be ideal to contract with Wholesaler&#39;s having a local presence in San Francisco and New York. These providers, in turn, can provide proxied access to the Corp A  employees without a large capital outlay. 
     While it might appear ideal to do this, this mechanism raises some problems. For example, if Corp A  has a great number of employees in San Francisco, they could overwhelm the PoP and prevent regular retail or other wholesale customers of the Wholesaler from enjoying the service that they paid for. Similarly, a large number of employees spread over many regions could potentially overwhelm the network maintained by the Wholesaler. Accordingly, the Wholesaler would like to enter into an arrangement with Corp A  whereby Corp A  pays a fee for a more or less specific number of proxied sessions to occur at any one time. When Corp A  exceeds this contracted number it is either cut off or charged an extra fee. In this way, the Wholesaler is able to plan for its expansion and receive realistic information on the number of these sessions that it must be able to support. Unfortunately, no current mechanism exists to enable this activity. 
     SUMMARY OF THE INVENTION 
     A data communications network with a plurality of PoPs maintains a local database associated with each PoP and a central database somewhere on the data communications network. The local database contains a group identification such as a domain identification corresponding to a group of users, a maximum number of proxied sessions to provide the group of users at the PoP and a dynamic proxy session count corresponding to active proxied sessions currently provided to the group of users at the PoP. The central database contains a maximum number of proxied sessions to provide the group of users over the entire data communications network and a dynamic network-wide proxy session count corresponding to active proxied sessions currently provided to the group of users on the entire data communications network. Actions are taken when the group attempts to exceed either the local maximum number of sessions or the network-wide maximum number of sessions by more than a predetermined number. The actions may include assessing extra charges, denying access, and sending warning messages to appropriate recipients. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a system block diagram of a simple ISP PoP using a conventional retail-only paradigm. 
     FIG. 2 is a system block diagram of wholesale ISP PoP using a conventional wholesale-only paradigm. 
     FIG. 3 is a diagram illustrating the information stored in a central database in accordance with a presently preferred embodiment of the present invention. 
     FIG. 4 is a diagram illustrating the information stored in a local database in accordance with a presently preferred embodiment of the present invention. 
     FIG. 5 is a system block diagram of a data communications network in accordance with a presently preferred embodiment of the present invention. 
     FIG. 6 is a flow diagram of a process for verifying slot availability for a proxy user on a data communications network in accordance with a presently preferred embodiment of the present invention. 
     FIG. 7 is a flow diagram of a process for updating slot availability information in a data communications network in accordance with a presently preferred embodiment of the present invention. 
     FIG. 8 is a system diagram of a data communications network in accordance with a presently preferred embodiment of the present invention. 
     FIG. 9 is a block diagram of a broker-publisher system used in a presently preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Those of ordinary skill in the art will realize that the following description of the present invention is illustrative only and not in any way limiting. Other embodiments of the invention will readily suggest themselves to such skilled persons after a perusal of the within disclosure. 
     In accordance with a presently preferred embodiment of the present invention, the components, processes and/or data structures may be implemented using C++ programs running on high performance computers (such as an Enterprise 2000™ server running Sun Solaris™ as its operating system. The Enterprise 2000™ server and Sun Solaris™ operating system are products available from Sun Microsystems, Inc. of Mountain View, Calif.). Different implementations may be used and may include other types of operating systems, computing platforms, computer programs, firmware and/or general purpose machines. In addition, those of ordinary skill in the art will readily recognize that devices of a less general purpose nature, such as hardwired devices, devices relying on FPGA (field programmable gate array) or ASIC (Application Specific Integrated Circuit) technology, or the like, may also be used without departing from the scope and spirit of the inventive concepts disclosed herein. 
     In accordance with one embodiment of the present invention the AAA proxy service may be implemented within a protocol gateway (PGW). PGWs are devices which couple users via a network access server (NAS) to the data communications network by dynamically converting protocols. The term gateway is not meant to be limited to a single type of device, as any device, hardware or software, that may act as a bridge between the user and the network may be considered a gateway for the purposes of this application. In accordance with one presently preferred embodiment of the present invention, the PGW may be a software service operating on a general purpose computer running the User Control Point (UCP) software package available from Cisco Systems, Inc. of San Jose, Calif. 
     The authentication, authorization and accounting (AAA) service performs user authentication, user authorization and user accounting functions. It may be a Cisco ACS™ product such as Cisco Secure™, available from Cisco Systems, Inc. of San Jose, Calif., or an equivalent product. In accordance with a presently preferred embodiment of the present invention, the Remote Authentication Dial-In User Service (RADIUS) protocol is used as the communication protocol for carrying AAA information. RADIUS is an Internet standard track protocol for carrying authentication, authorization, accounting and configuration information between devices that desire to authenticate their links and a shared AAA or AAA proxy service. Those of ordinary skill in the art will realize that other authentication protocols such as TACACS+ or DIAMETER can be used as acceptable authentication communications links between the various communications devices that encompass the data communications network and still be within the inventive concepts disclosed herein. 
     In accordance with the present invention wholesale users such as Corp A  and Corp B  will subscribe with a Wholesaler for a certain level of proxy session coverage both a particular PoPs on the network and network-wide. For example, the wholesale user could subscribe to a maximum number of proxy sessions of 50 network wide and 15 at a particular PoP. If the maximum is exceeded either at the PoP or network-wide then the next attempted log in can be handled in a number of different ways. First, it can simply be refused. Second, it can be accepted up to an “absolute maximum” of, say, 100 network-wide and 25 at the PoP. This absolute maximum provides some warning room before denying service to a user. Optionally, wholesale customers can be warned when they are exceeding the maximum without suffering a denial of service. They may also be charged an extra fee for the extra service, if desired. The extra fee would be charged by initiating a special RADIUS accounting packet in response to the log in over the maximum and sending it to the proper AAA service. Ideally the wholesale customer would adjust its service contract to the level of use it is actually making of the network and the PoPs. 
     To implement the invention, it is necessary to keep track of data not previously tracked in a data communications network. Central database  30  shown in FIG. 3 maintains a list identifying domains (or otherwise identifying customer “groups”) that have subscribed to wholesale proxy access at PoPs on the data communications network. Each domain or other group identification has associated therewith a value for “network maximum sessions” which indicates the number of proxy sessions that the domain is ordinarily entitled to on a network-wide basis. In the example of FIG. 3, Corp A  is entitled to 50 and Corp B  is entitled to 75. Normally this means that if a user from Corp A  dials into a PoP, the Wholesaler is required to service the user as long as the user&#39;s log in won&#39;t exceed the maximum network-wide or at the PoP. The Wholesaler may provide this access in a conventional manner. 
     Note that the “group” may be based on network domain name such as “corpa.com,” or on -some other determinable characteristic. Since the DNIS ID and/or the CLID may be used, it is possible to group users by the telephone numbers that they call from or dial into. Hence a group may have any number of diverse users in it. The term “group” will be used herein for simplicity, but it is meant in this broader sense to be inclusive of any such determinable group of users. 
     Optionally, a “Network Absolute Maximum Sessions” value may be kept to indicate how many sessions the domain may actually get before denial of service. In the example of FIG. 3 Corp A  is entitled to 100 and Corp B  is entitled to 150. As pointed out above, there may be an extra charge levied for exceeding the network maximum sessions value. 
     The Central Database  30  also keeps a count of the current proxy sessions in effect network wide. This count is maintained by the broker-publisher system described in more detail below. 
     A Wholesaler may wish to take action in a conservative manner, as by adding a fixed number of “grace” sessions to avoid penalizing a client before the client has clearly exceeded the terms of its service contract by more than a reasonable level. On the other hand, the “grace” number may also be set to zero. 
     The Central Database  30  may also contain additional information as desired including a mirror of same or all of the data contained in the local databases  40  if desired. 
     Local Database  40  as shown in FIG. 4 are associated with each PoP. They may be stored in local cache memory at each PoP or in any other convenient fashion. There is no requirement that they be stored at the PoP, it just may be convenient to do so. 
     Local Database  40  operates much like Central Database  30 . Local Database  40  relates to a single PoP and contains a list of domain or customer identifications coupled with a local maximum sessions value, local absolute maximum sessions value and a local session count value indicative of the actual current number of proxy sessions belonging to the group and occurring at the particular PoP. 
     As before, attempts to log in more than the permitted number of local proxy sessions can be handled in a number of different ways. Local proxy session log ins increment the appropriate domain&#39;s local session count and log outs decrement the count. 
     FIG. 5 is a simplified block diagram of a data communications network  50  in accordance with a presently preferred embodiment of the present invention. The Network includes PoP 1 , PoP 2  and PoP 3 . Each of PoP 1 , PoP 2  and PoP 3  has an associated local database  52 ,  54 ,  56  as shown. A network operations center (NOC).includes a primary mother cache (PMC) and a redundant secondary mother cache (SMC) as known to those of ordinary skill in the art. The PMC and SMC are preferably used to store the Central Database  30 . 
     FIG. 6 is a flow diagram illustrating the log in process for a proxy user in accordance with a presently preferred embodiment of the present invention. At block  60  the user attempts the log in at a local PoP. At block  62  the group of the user is determined. This may be done in one of several ways as discussed above, but most commonly involves parsing the FQDN of the user. At block  64  the local database  40  is searched for the group entry corresponding to the user. If proxy session slots are available (i.e., absolute maximum sessions is not exceeded if this session is to be allowed) then control transfers to block  70 . Otherwise, the log in is rejected at block  66  and optionally the group administrator and/or user is notified in a conventional manner as set forth in the process at block  68 . 
     Optionally, some sort of “grace” level may be applied at block  64  so that rejection of log in does not occur precisely at the level specified in the service agreement with the domain. 
     At block  70  the central database  30  is queried to see if slots or log in opportunities are available. If they are, control transfers to block  72 , otherwise the log in attempt may be rejected. “Grace” slots may also be considered for application here. 
     At block  72 , the session count in the local database  40  is incremented. At block  74  the session count in the central database  30  is incremented. At block  76  the user is permitted to proxy access the domain. This may, or may not, result in the user gaining further access to the data communications network as the user must still be authenticated and authorized, presumably by an AAA service at Corp A . 
     When a user logs out, it is important to decrement the session counts so that an accurate session count is always kept locally as well as centrally. FIG. 7 shows how this is done. At block  78  the user initiates the log out process. At block  80  the local session count in local database  40  is decremented. At block  82  the central session count in central database  30  is decremented. 
     FIG. 8 is a system block diagram of a portion of data communication network  50  in accordance with a presently preferred embodiment of the present invention. Network Operations Control Center (NOC)  100  is located centrally on the network  50 . There may be more than one NOC on a particular data communications network. Typically each Wholesaler will have at least one NOC. The Primary Mother Cache (PMC  102 ) and Secondary Mother Cache (SMC  104 ) are memory storage components associated with NOC  100 . An access database adapter  106  is in communication with PMC  102  and SMC  104  as well as an information bus  108 . This adapter, and other adapters in the invention, provide bi-directional mapping of information between components and other services comprising the data communications network  50 . Adapters, such as the access database adapter  106  subscribe to and publish events. An event is an independent entity which contains an unspecified amount of non-time critical information. For example, the access database adapter  106  receives commands to publish an event. The information contained in the event may be found in the request or the access database adapter  106  may communicate with the PMC  102  to find the required information. The event is then published to other services and components within the data communications network across an information bus  108  which may be the data communications network itself. Of course this is only one way to achieve data synchronization—those of ordinary skill in the art can now implement a centralized model or a fully meshed communication model to achieve the same end. 
     The information bus  108  that serves as the transportation medium for the presently preferred embodiment of the present invention can be Common Object Request Broker Architecture (CORBA)-based. The CORBA-based information bus is capable of handling the communication of events to and from objects in a distributed, multi-platform environment. The concept of a CORBA-based information bus is well known by those of ordinary skill in the art. Other acceptable communication languages can be used as are also known by those of ordinary skill in the art. Other transportation models are available as well, such as the Distributed Component Object Model (DCOM), which will readily achieve the same end. 
     CORBA provides a standard way of executing program modules in a distributed environment. A broker  110 , therefore, may be incorporated into an Object Request Broker (ORB) within a CORBA compliant network. To make a request of an ORB, a client may use a dynamic invocation interface (which is a standard interface which is independent of the target object&#39;s interface) or an Object Management Group Interface Definition Language (OMG IDL) stub (the specific stub depending on the interface of the target object). For some functions, the client may also directly interact with the ORB. The object is then invoked. When an invocation occurs, the ORB core arranges so a call is made to the appropriate method of the implementation. A parameter to that method specifies the object being invoked, which the method can use to locate the data for the object. When the method is complete, it returns, causing output parameters or exception results to be transmitted back to the client. 
     In accordance with a presently preferred embodiment of the present invention an Enterprise Application Integration (EAI) system is used to broker the flow of information between the various services and adapters comprising the data network management system of the present invention. An example of an EAI system that can be incorporated in the presently preferred invention is the ActiveWorks Integration System, available from Active Software of Santa Clara, Calif. As shown in FIG. 9, such an EAI system  112  uses an information broker  110  as the hub of the system. The information broker  110  acts as the central control and storage point for the system. The information broker  110  can reside on a server and serves to mediate requests to and from networked clients; automatically queuing, filtering and routing events while guaranteeing delivery. The information broker  110  is capable of storing subscription information and using such subscription information to determine where published information is to be sent. Referring back to FIG. 8, the information broker  110  is shown as being located at a point along the information bus  108 . In most instances, the broker will be located within the same NOC  100  as the host that runs the access database adapter  106  application. Another key feature to the EAI system  112  of FIG. 9 is the use of service adapters  112  and  114  that allow users of the EAI system  112  to integrate diverse applications and other information when using the integration system. Service adapters  112  and  114  provide bi-directional mapping of information between an application&#39;s native format and integration system events, enabling all custom and packaged applications, databases, and Internet and other network applications to exchange information. As shown in FIG. 9 the adapters  112  and  114  run in association with the various services  116  and  118  from which information is published and subscribed on to an information bus  108  that has its hub at the broker  110 . 
     Referring back to FIG. 8 the information bus  108  is in communication with a Point of Presence (POP) (POP 1 ) within the data communications network  50 . POP 1  is one of many PoPs with which the information bus  108  is in communication. Located within PoP 1  is a host or node which may comprise one or more computing devices on which some or all of the services shown in FIG. 8 may be running. The node is in communication with the information bus  108  through a control adapter  116  which provides control communications with the various services such a PGW  118  through their respective service adapters  114 , via service adapter  112  of control adapter  116 . Those of ordinary skill in the art will appreciate that the services shown are not intended to be limiting and that other services and other service configurations can be used without departing from the inventive concepts herein disclosed. The system services may also be distributed over two or more servers to provide improved performance and redundancy. 
     The protocol gateway service  118  is used to couple the network user to the data communication network. The protocol gateway service  118  functions as an interface to the NASes that allows access requests received from a user to be serviced using components that may communicate using different protocols. A typical protocol gateway service  118  may be able to support different user access methodologies, such as dial-up, frame relay, leased lines, Cable DSL (Digital Subscriber Line), and the like. 
     Thus, in one embodiment of the invention, the broker-publisher system described above is used to publish log in events from the PGW  118  or other access port of the data communications network  50  to the central database at the PMC  102  (and SMC  104 ). Similarly, the local databases may subscribe to receive the central database information so that the decision to accept or reject may be made locally at the PoP, or they may simply query the PMC  102  to determine if an incremental user may log in. In an alternative embodiment, the central database may be omitted and each local database will then subscribe to each other local PoP&#39;s proxied log ins and proxied log outs so as to locally maintain a current network-wide session count as well as a local session count. 
     Alternative Embodiments 
     While embodiments and applications of the invention have been shown and described, it would be apparent to those of ordinary skill in the art, after a perusal of the within disclosure, that many more modifications than mentioned above are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except in the spirit of the appended claims.