WO2001035294A1

WO2001035294A1 - Combining internet protocols for session setup, teardown, authentication, authorization, and accounting using the differentiated services model

Info

Publication number: WO2001035294A1
Application number: PCT/US2000/030448
Authority: WO
Inventors: Steven R. Donovan
Original assignee: Mci Worldcom, Inc.
Priority date: 1999-11-05
Filing date: 2000-11-06
Publication date: 2001-05-17
Also published as: US20050213584A1; MXPA02004491A; AU1464801A; US20090154468A1; US9577933B2; CA2390179A1; WO2001035294A9; EP1232458A4; US6970930B1; BR0015351A; JP2003514415A; CN1413333A; US7830888B2; EP1232458A1; AU775853B2

Abstract

A method for combining Internet protocols in a Differentiated Services model environment is described. The Session Initiation Protocol (SIP) and Common Open Policy Service (COPS) are combined together to provide methods of setting up a session (1) and tearing down a session, while maintaining Authentication, Authorization, and Accounting (AAA) policies (2). The Open Settlement Policy (OSP) is also combined with SIP and COPS. This combination provides for an interchange of parameters between session setup, teardown, authorization, policy, Quality of Service (QoS), and usage reporting.

Description

COMBINING INTERNET PROTOCOLS FOR SESSION SETUP, TEARDOWN AUTHENTICATION, AUTHORIZATION, AND ACCOUNTING USING THE DIFFERENTIATED

BACKGROUND OF THE INVENTION

1. Field nf the Invention

The present invention relates generally to the field of Internet multimedia communication, and, more particularly, to a method for combining Internet protocols for session

setup, teardown, authorization, and accounting in a Internet Protocol (IP) network, which uses the DifϊSERV (Differentiated Services) model in order to guarantee Quality of Service (QoS).

2. Description of the Related Art

The invention of the telephone opened an unprecedented era in personal communication. At the present time, the Internet is opening up another era in personal communication, allowing a

level of interactivity previously unknown between computers and groups of computers. In the

future, these two services will be combined into one seamless communication medium.

However, the concepts underlying the telephone system and the Internet are fundamentally different. The telephone system is circuit-based; meaning that, for example,

when a call is set up between caller and callee, a dedicated line, or circuit, is maintained between the two, and, when the call is over, the dedicated line is taken down. The Internet is packet- based; meaning that, for example, when a user downloads a web page, or receives an e-mail, the data that comprises the web page or e-mail is broken down to packets before being transmitted.

The individual packets, although they form one web page or one e-mail message, may take entirely different routes between the sender and the destination. The destination computer puts all the packets together to form the web page.

A fundamental problem lies in providing a circuit-based service, such as a telephone call

or videoconferencing, over a packet-based network. While the answer may appear

simple-digitize and packetize the audio or visual information - the situation is more complicated

than it appears. For one thing, an application such as a telephone call requires a constant

transmission rate; something the current Internet cannot guarantee. An application such as videoconferencing using MPEG has stringent real-time requirements in order to avoid the displayed motion appearing jerky. These requirements include a variable transmission rate and very little jitter in the packet arrival times. Once again, at present the Internet cannot guarantee

these requirements will be met.

One system for addressing these Quality of Service (QoS) issues on the Internet is the

DiffServ model, or Differentiated Services architecture (RFC 2475). In DifϊServ, packet traffic shaping is implemented by network routers. In order to specify the transmission requirements, DifϊServ uses the Type of Service (ToS) bits in the Internet Protocol (IP) packet header (see FIG. 1). Although the ToS field exists in the current protocol IPv4 (Internet Protocol, version 4), most routers do not use or read the bits in the ToS field. DiffServ uses these bits to tell the router the

priority of the packet. Because of this, the ToS field in the IP header is referred to as the DS

field.

DifϊServ is implemented in the following manner: when packet traffic enters a DifϊServ network, the packets are classified and possibly conditioned at the network boundary, most likely in an edge router. The DS field will be filled in with the appropriate bits for that type of traffic,

which may depend on customer usage, media specification, general policy, etc. The network

nodes inside the DiffServ network will read the DS field to determine how to manage incoming

packets. For instance, if an edge router recognizes incoming packets as being high priority, the router will classify those packets as high priority in the DS field, and then send those packets inside the network. When those high priority packets reach a network node, the node will forward them before other packets, because the DS field indicates that they are high priority. This example is somewhat of a simplification, for the DS field classification scheme is more

complicated than merely high or low priority, and takes into account throughput, delay, jitter, packet loss, and other traffic characteristics. Taken together, these traffic characteristics make up

Quality of Service (QoS).

Because DiffServ classifies these packets into different categories, it works only upon "flow aggregates," which refers to a collection of packet flows. In other words, an interior network node does not know what a packet contains or if that packet is part of a series of packets; the interior node merely treats it as a member of a certain classification of traffic characteristics.

This is in contrast to another method of assuring QoS over a network, the Resource ReSerVation

Protocol (RSVP). RSVP sets up a path from network node to network node for a particular packet flow. For example, if an end client device wishes to establish a telephone call over the network, the device would use RSVP to establish a path to the callee's end client device through one or more network nodes. The individual network nodes on the path would then know that a particular identified packet flow will require certain traffic conditions, and resources will be

reserved for them. When a node receives one of the packets in the series of packets, the node

will recognize it and behave accordingly. While DifϊServ looks at flow aggregates, RSVP looks

at individual "micro-flows."

For the rest of this description, a DifiServ environment will be assumed. This means that the QoS requirements will be handled by edge routers which will tag individual packets appropriately, while interior network nodes will act upon packets based merely on their DS field.

Even assuming the QoS problems are being handled by DifϊServ, there are other services

automatically handled in a circuit-based environment which are problematic in an IP-based network. A call has to be set up, establishing a connection between the two end devices, and the resources used in an individual call or session must be tracked, for accounting purposes. In

addition, there needs to be the capability to have only authorized sessions or calls from

- A - authenticated users. In the Internet framework, these issues are resolved by different protocols that do different things. Although these individual protocols have been developed in detail, there

is at present known method that sets forth how to use them together in a consistent way across the Internet.

Thus, there is a need for linking these protocols together in a consistent and workable way. In particular, there is a need for a method providing an interchange of parameters among protocols between session setup, authorization, policy, and usage reporting that will support IP communications between Internet Service Providers (ISPs), enterprise networks, and individual clients.

SUMMARY OF THE TNVENTIO

The present invention provides a method for providing an interchange of parameters among protocols for session setup, teardown, authorization, policy, and usage reporting that will support IP communications in a Differentiated Services model environment.

The present invention provides a method for session or call setup, teardown, authorization, policy and usage reporting in a common way of usage, thereby supporting IP communications across the Internet.

The present invention also provides a method to link together the Session Initiation Protocol (SIP), Common Open Policy Service (COPS), and Open Settlement Policy (OSP) in a Differentiated Services model environment.

These and other objects are achieved by the preferred embodiment of the present invention. In the preferred embodiment, the messages from the Session Initiation Protocol (SIP),

Common Open Policy Service (COPS), and Open Settlement Policy (OSP) are interwoven so that session setup, authorization, policy, and usage reporting are all performed concurrently, in one unified sequence of messages. Likewise, the messages from the Session Initiation Protocol (SIP), Common Open Policy Service (COPS), and Open Settlement Policy (OSP) are interwoven so that session teardown, authorization, policy, and usage reporting are all performed concurrently, in one unified sequence of messages.

BRTEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with

the accompanying drawing in which:

FIG. 1 shows an Internet Protocol Header;

FIG. 2 shows the components of a SIP-based network and an overview of initiating a

session;

FIG. 3 shows the components of a Common Open Policy Service (COPS) system;

FIG. 4 shows the components of a Open Settlement Protocol (OSP) system; FIG. 5 shows a session initiation setup according to an embodiment of the present

invention; and

FIG. 6 shows a session teardown according to an embodiment of the present invention.

DETAILED DESCRIPTION O THE PREFERRED EMBODIMENTS

As stated above, in the prior art there has been no linkage between the individual protocols that provide for call setup, authorization, accounting, and authentication These steps

are taken care of by the following protocols:

Session Initiation Protocol (SIP) - for setting up connections, or calls;

Common Open Policy Service (COPS) - for policy deployment in network elements; and

Open Settlement Protocol (OSP) - for authorization and usage reporting.

These protocols will be discussed in detail below. In these discussions, the terms "client" and "server" will be used in their abstract functional sense, as processes that may be implemented in any sort of device. This means, of course, that some servers and clients may be ninning in the same device.

a) Session Initiation Protocol fS SIP is a signaling protocol that allows for initiating and tearing down connections. There are two components in a SIP system: network servers and user agents. A user agent is an end system that acts on behalf of someone who wants to participate in calls. In general, the user agent contains both a protocol client (a user agent client UAC) which initiates a call and a protocol server (user agent server UAS) which responds to a call (see FIG. 2). There are two different type of network servers as well: a proxy server, which receives requests, determines which server to send it to, and then forwards the request; and a redirect server, which receives

requests, but instead of forwarding them to the next hop server, tells the client to contact the next hop directly.

The steps in initiating a session are fairly simple: as shown in FIG. 2, (1) the UAC sends an I VITE request to a SIP server, which in this case, is a proxy server. The proxy server will look in its database to determine where to send the INVITE request. Once that is determmed, the

proxy server sends the INVITE message to the appropriate next hop. In FIG. 1, the next hop is

the callee, but, in reality, there could be a number of hops between the proxy server and the

callee. If the proxy server is a redirect server, it would inform the UAC what the appropriate next hop is, and let the UAC do the rest. Once (2) the INVITE message finally reaches the callee

UAS, (3) the callee UAS responds with an OK message, which (4) is forwarded to the caller

UAC. When the caller UAC receives the OK message, indicating the callee has received the

INVITE, (5) the UAC sends an ACK message, which, when (6) received, will start the session. The steps in terminating a session, or teardown, are even more simple: the UAC sends a BYE message, and the UAS sends a message indicating receipt of the BYE message. In SIP, either the UAC or the UAS may send the B E message terminating a session.

b) Common On en Policy Service TCOPS^

COPS is a simple query and response protocol that can be used to exchange information

between a policy server (Policy Decision Point or PDP) and its clients (Pohcy Enforcement Points or PEPs), as shown in FIG. 3. A policy is a combination of rules and services that define the criteria for resource access and usage. In COPS the PEP sends requests, updates, and deletions to the PDP and the PDP returns decisions back to the PEP. The basic message formats for COPS include Requests (REQs), Decisions (DECs), and Report States (RPTs), among many others.

When particular events occur at a PEP, such as the initiation of a session, the PEP will send a EQ to the PDP to determine the pohcy regarding the session. The REQ may be an

Authentication, Authorization, Accounting (AAA) REQ, which is asking that the session be authorized, authenticated, and kept track of for accounting purposes. If the PDP determines the

session fits the AAA policy, the PDP will send its decision DEC to the PEP, thus allowing the

PEP to allocate the needed resources. The RPT message is used by the PEP to communicate to the PDP its success or failure in carrying out the PDP's decision, or to report an accounting related change in state.

c) Open Settlement Protocol fOSP^

OSP is used when there is a central clearinghouse for certain policy decisions. As shown in FIG. 4, OSP is the protocol describing communication between the policy server PDP and the clearinghouse server. This is needed in large networks which require multiple policy servers.

Among other things, authorization for QoS levels is handled by the clearinghouse server. The clearinghouse server can also be a trust broker between a large number of network providers and

the collecting place for usage reports. As an example, if a PEP sends a REQ AAA to a PDP, the PDP sends a message to the clearinghouse server in order to authorize the call or session. This message is in the form of a <AuthReq>, and the clearinghouse server responds with a

<AuthRsp>, which may or may not contain an authorization token, which permits the REQ AAA to proceed. In addition, when a connection or session ends, the use of resources for that session

or connection must be recorded for accounting purposes. When the policy server PDP de-installs

a particular QoS policy, i.e. registers the end of a session, the pohcy server PDP sends a <UsageInd> message to the clearinghouse server so that the resource usage is recorded as well as monitored. The clearinghouse confirms the <UsageInd> with a <UsageCnJ>.

As stated above, these protocols have been extensively defined and implemented, but to date there has been no common way of usage for combining them. A preferred embodiment of the present invention, as described below, combines these protocols in order to provide a consistent and common manner of usage for IP-based networks using the Differentiated Services

model. In the description below of FIG. 5, a session setup according to the preferred embodiment of the invention will be explained in detail. In the description below of FIG. 6, a session teardown will be explained in detail.

Referring to FIG. 5, at the origination end, there is a SIP user agent client UAC which is

attempting to start a session, and the UAC has a local SIP proxy server SIP1, a local Policy server POL1, and a local Router Rl. At the destination end, there is a SIP user agent server UAS, which the UAC is attempting to call, and the UAS has local SIP proxy server SEP2, a local Policy server POL2, and a local Router R2. Both the UAS and UAC share the same Clearinghouse CH, shown in the middle. Both POLl and POL2 are acting as PDPs, and SIP1 and SIP2 arc their corresponding PEPs. In the preferred embodiment, when the Clearinghouse sends a positive response to a resource usage request, the Clearinghouse also sends an

authorization token. The unit receiving the call is the SIP user agent server UAS, which may be running in any type of IP telephone, computer, media device, or gateway. As stated above, both routers Rl and R2 are working based on the DifϊServ model. Therefore, the routers will enforce

QoS by altering the DS field in incoming session packets.

In general, the call setup request, authorization and policy installation occur as follows:

1 ) The UAC sends an INVITE message requesting call setup to SEP 1 ; 01/35294

2) SIP 1 sends a REQ AAA message requesting authentication, authorization, and

accounting for the UAC SIP session to the local policy server POL1;

3) Local policy server POL1 sends a AuthRcq> message to the clearinghouse

server CH;

4) The Clearinghouse server CH responds with a AuthRsp> authorizing the session

and sending an authorization token to POL 1 ;

5) POL1 sends a DEC message to SIP1, authorizing installation of the session;

6) SIP 1 now forwards the INVITE message to SP2;

7) SIP2 sends a REQ AAA message requesting authentication, authorization, and

accounting for the SIP session to the local policy server PO 2;

8) Local pohcy server POL2 sends a <AuthReq> message to the clearinghouse

server CH;

9) The clearinghouse server CH responds with a <AuthRsp> authorizing the session and sending an authorization token to POL2;

10) POL2 sends a DEC message to SJP2, authorizing installation of the session;

11 ) SIP2 now forwards the INVITE message to user agent server UAS;

12) UAS responds with a 180 RINGING message, which means the UAS is

alerting the user to the session;

13) SIP2 sends a REQ LDP message to POL2. This message requests that the

appropriate policy be loaded onto R2 concerning this session; it is a local decision

point (LDP) message, because the local policy server POL2 will make this decision, not the clearinghouse;

14) POL2 sends a DEC message to R2, telling R2 of the appropriate policy for the session packets. Since this is a DifiServ environment, router R2 will enable QoS

by filling in the DS field of the session packets appropriately when they arrive at the router R2;

15) R2 responds with a RPT message indicating that the pohcy was installed;

16) POL2 informs SIP2 with a DEC message to install the same policy;

17) SIP2 now forwards the 180 RINGING message to SIP 1 ;

18) SIP1 sends a REQ LDP message to POLl. This message requests that the appropriate policy be loaded onto Rl concerning this session; it is a local decision point (LDP) message, because the local policy server POLl will make this decision, not the clearinghouse;

19) POLl sends a DEC message to Rl, telling Rl of the appropriate policy for the session packets. Since this is a DiffServ environment, router Rl will enable QoS by filling in the DS field of the session packets appropriately when they arrive at the router Rl ;

20) R1 responds with a RPT message indicating that the policy was installed;

21 ) POL1 informs SIP1 with a DEC message to install the same policy;

22) SIP1 now forwards the 180 RINGING message to UAC;

23) UAS responds with a 200 OK message;

24) SIP2 forwards this message to SIP1 ; 25) SIP1 forwards this message to UAC;

26) UAC acknowledges with an ACK message;

27) SIP1 forwards the ACK message to the SIP2;

28) SIP2 forwards the ACK message to UAS;

29) The session or connection commences.

The actual sequence of messages is divided between the three protocols: message steps 1 , 6, 11 , 12. 17, and 22-9 are SIP messages; message steps 2, 5, 7,

10, 13-16, 18-21 are COPS messages; and message steps 3-4 and 8-9 are OSP

messages. In this manner, the preferred embodiment of the present invention links the three protocols for call setup, authorization, and accounting. Although the above sequence has been described with a clearinghouse server, the preferred embodiment

can work in a system without a clearinghouse. In such a network, the policy server handles most of the clearinghouse tasks, and message steps 3-4 and 8-9 would take place inside the policy server.

FIG. 6 shows the steps of a session teardown according to an embodiment of the present invention. The preferred embodiment also links together the protocols

when ending a session, as shown in the following sequence of steps:

1 ) UAC signals the end of the session with a BYE message;

2) SIP1 forwards the BYE message to SIP2; 3) SIP2 forwards the BYE message to UAS;

4) SIP1 sends a REQ noLDP message canceling the policy given in the original REQ LDP message in message step 18 of the setup message

sequence above;

5) POL1 sends a DEC Remove message to R1, telling the router to de-install

the policy. Since this is a DiffServ environment, the router, up to this point, has been altering the DS field in each of the session packets that arrived. Now, the router will de-install that policy, and stop looking for this

session's packets;

6) R1 confirms the policy de-installation with a RPT message to POL1 ;

7) POL1 sends a DEC message to SIP1 , telling the server to de-instail the policy;

8) POL1 sends a <Usagelnd> message detailing the resource usage to clearinghouse CH;

9) CH confirms with a <UsageCnf> message;

10) UAS sends a 200 OK message confirming receipt of the BYE message;

11 ) SIP2 forwards the OK message to SIP1 ;

12) SIP1 forwards the OK message to UAC;

13) SIP2 sends a REQ noLDP message canceling the policy given in the original REQ LDP message in step 13 of the setup message sequence

above; 14) POL2 sends a DEC Rem message to R2, telling the router to de-install

the policy. Since this is a D^'rffServ environment, the router, up to this

point, has been altering the DS field in each of the session packets that arrived. Now, the router will de-install that policy, and stop looking for this session's packets;

15) R2 confirms the policy de-installation with a RPT message to POL2;

16) POL2 sends a DEC message to SIP2, telling the server to de-install the policy;

17) POL2 sends a <Usagelnd> message detailing the resource usage to CH; and

18) CH confirms with a <UsageCnf message;

As with the setup message sequence described above, the actual sequence of messages is divided between the three protocols: message steps 1 , 6, 11, 12, 17, and

22-9 are SIP messages; message steps 2, 5, 7, 10, 13-16, 18-21 are COPS messages;

and message steps 3-4 and 8-9 are OSP messages. In this manner, the preferred embodiment of the present invention links the three protocols for call tear-down and usage reporting. Although this has been described with a clearinghouse server, the

preferred embodiment can work in a system without a clearinghouse. In such a network, the policy server handles most of the clearinghouse tasks, and message steps

3-4 and 8-9 would take place inside the policy server. While an embodiment of the present invention has been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

WHAT LS CLAIMED IS:

1. A method for providing Internet Protocol (IP) communications over at least one network with Quality of Service (QoS), comprising the steps of: establishing at least one QoS policy in at least one network node; initiating a communication session between at least one first end client

device and at least one second end client device; providing information to at least one server of the communication session,

said information including at least one of resource usage, policy, authorization, authentication, and accounting information; providing information to at least one router of the communication session, said information including at least one of resource usage, policy, authorization, authentication, and accounting information; and

establishing a communication session between said at least one first end

client device and said at least one second end client device.

2. The method as recited in daim 1 , wherein said step of establishing at least one QoS policy in at least one network node uses a Differentiated Services model.

3. The method as recited in claim 1 , wherein the step of initiating a

communication session further comprises the steps of: a) sending an initiation message from said at least one first end client

device to said at least one second end client device;

b) sending a message indicating receipt of said Initiation message by

the at least one second end client device;

c) sending a message indicating the at least one second end client device is responding to the initiation message; and d) sending a message indicating a receipt of the message in (c) by the at least one first end client device and signaling the start of the communication

session.

4. The method as recited in claim 3, wherein said steps (a)-(d) use a Session Initiation Protocol (SIP).

5. The method as recited in claim 3, wherein said network includes at least one server for receiving and forwarding initiation messages.

6. The method as recited in claim 1, wherein said at least one server is a policy server, the step of providing information to said at least one server of the communication session, further comprises the steps of: a) sending a message requesting said at least one of resource usage,

policy, authorization, authentication, and accounting information to at least one policy server: and b) sending a message responding to the message in (a) with at least one of resource usage, policy, authorization, authentication, and accounting information; wherein said at least one of resource usage, policy, authorization, authentication, and accounting information is according to the at least one QoS policy.

7. The method as recited in claim 6, wherein steps (a) and (b) are performed

on a plurality of policy servers, one of the plurality of policy server being a local policy

server for the first end client device, and one of the plurality of policy servers being a local policy server for the second end client device.

8. The method as recited in claim 6, wherein said steps (a) and (b) use a Common Open Policy Service (COPS).

9. The method as recited in claim 1 , wherein the step of providing information to at least one router of the communication session, further comprises the steps of:

a) sending a message requesting a local policy decision, b) sending a message installing policy to at least one router; and

c) sending a message confirming installation.

10. The method as recited in claim 9, wherein the at least one router performs

according to a Differentiated Services model.

11. The method as recited in claim 9, wherein steps (a)-(c) are performed on a plurality of routers, one of the plurality of routers being a local router for the first end client device, and one of the plurality of routers being a local router for the second end client device.

12. The method as recited in claim 9, wherein steps (a)-(c) use a Common

Open Policy Service (COPS).

13. The method as recited in claim 7, wherein said network includes at least one clearinghouse server, said clearinghouse server providing resource usage, policy, authentication, authorization, and accounting information to each of said plurality of

policy servers, said method further comprising the steps of:

a) sending a message requesting at least one of resource usage, policy, authentication, authorization, and accounting Information to the at least one clearinghouse server; and b) sending a message including at least one of resource usage, policy, authentication, authorization, and accounting information to the at least one

policy server.

14. The method as recited in claim 13, wherein said steps (a) and (b) use a Open Settlement Policy (OSP).

15. The method as recited in claim 1 , wherein the network uses an authorization token to indicate that a session is authorized.

16. A method for providing Internet Protocol (IP) communications over at least

one network with Quality of Service (QoS), comprising the steps of: establishing at least one QoS policy in at least one network node; terminating a communication session between at least one first end client device and at least one second end client device; providing information to at least one server of the communication session, said information including at least one of resource usage, policy, authorization,

authentication, and accounting information; and

providing information to at least one router of the communication session, said information including at least one of resource usage, policy, authorization,

authentication, and accounting information.

17. The method as recited in claim 16, wherein said step of establishing at

least one QoS policy in at least one network node uses a Differentiated Services model.

18. The method as recited in claim 16, wherein the step of terminating a communication session further comprises the steps of:

a) sending a termination message from the said at least first end client device to said at least one second end client device; and b) sending a message indicating receipt of said termination message by the at least one second end client device.

19. The method as recited in claim 18, wherein said steps (a)-(b) use a Session Initiation Protocol (SIP).

20. The method as recited in claim 16, wherein said network includes at least one additional server for receiving and forwarding termination messages.

21. The method as recited in claim 16, wherein said at least one server is a

policy server, the step of providing information to said at least one server of the communication session, further comprises the steps of: a) sending a message requesting the de-installation of policy corresponding to terminating the session to at least one policy server; and b) sending a message responding to the message in (a) confirming

the de-installation of said policy.

22. The method as recited in claim 21 , wherein steps (a) and (b) are performed a plurality of policy servers, one of the plurality of policy servers being a local

policy server for the first end client device, and one of the plurality of policy servers^" being a local policy server for the second end client device.

23. The method as recited in claim 21 , wherein said steps (a) and (b) use a Common Open Policy Service (COPS).

24. The method as recited in claim 16, wherein the step of providing information to at least one router of the communication session, further comprises the steps of: a) receiving a message requesting de-installation of a local policy decision corresponding to the terminating session,

b) sending a message directing a de-installation of said policy to at least one router; and c) receiving a message confirming de-installatlon.

25. The method as recited in claim 24, wherein the at least one router performs according to a Differentiated Services model.

26. The method as recited in claim 24, wherein steps (a)-(c) are performed on

a plurality of routers, one of the plurality of routers being a local router for the first end client device, and one of the plurality of routers being a local router for the second end

client device.

27. The method as recited in claim 24, wherein steps (a)-(c) use a Common Open Policy Service (COPS).

28. The method as recited in claim 24, wherein a policy server performs step (a), said method further comprising:

storing information concerning at least one of resource usage, policy,

authorization, authentication, and accounting information concerning the terminating session.

29. The method as recited in claim 22, wherein said network includes at least

one clearinghouse server, said clearinghouse server storing resource usage, policy, authentication, authorization, and accounting information for each of said plurality of policy servers, said method further comprising the steps of: a) sending a message reporting at least one of resource usage, policy, authentication, authorization, and accounting information concerning terminating

the session to the at least one clearinghouse server; and

b) sending a message confirming the receipt of the message in step (a) to the at least one policy server.

30. The method as recited in claim 29, wherein said steps (a) and (b) use an

Open Settlement Policy (OSP).

31. The method as recited in claim 16, wherein the network uses an authorization token to indicate that a session is authorized.