[Sip] B2B UA definition
"Medhavi Bhatia" <mbhatia@nextone.com> Tue, 30 July 2002 04:05 UTC
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From: Medhavi Bhatia <mbhatia@nextone.com>
To: sip@ietf.org
Date: Mon, 29 Jul 2002 23:50:44 -0400
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Subject: [Sip] B2B UA definition
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Hi all, Very many times I have seen a discussion on B2B UA's end merely in a definition of a B2BUA: "A back-to-back user agent (B2BUA) is a logical entity that receives a request and processes it as a user agent server (UAS). In order to determine how the request should be answered, it acts as a user agent client (UAC) and generates requests. Unlike a proxy server, it maintains dialog state and must participate in all requests sent on the dialogs it has established. Since it is a concatenation of a UAC and UAS, no explicit definitions are needed for its behavior." However I believe this is quite incomplete. For example: 1) A B2BUA behaves similar to a proxy in that it must maintain "timer C" on outgoing transactions - which is unlike a UAC. 2) It SHOULD maintain max forwards on request in/requests out basis. Moreover it SHOULD have a defined relationship between incoming and outgoing requests. The way the definition goes, the outgoing request can have completely new headers, which eventually will cause a problem in loop detection/ policy and configuration at a remote destination. Clearly there may be reasons for new headers, but certain headers should be maintained for proper SIP network operation. 3) It has a notion similar to a response context of a proxy, and thus of forking requests etc etc... I believe that the SIP rfc describes a "server" role as a stateful/stateless proxy and completely specifies it. However a "server" can also be implemented as a B2BUA, so it should talk some more about it, or the requirements should be spelled out somewhere. A completely loose definition might just lead to deployment problems in future. -Medhavi. _______________________________________________ Sip mailing list https://www1.ietf.org/mailman/listinfo/sip This list is for NEW development of the core SIP Protocol Use sip-implementors@cs.columbia.edu for questions on current sip Use sipping@ietf.org for new developments on the application of sip
- [Sip] B2B UA definition Medhavi Bhatia
- Re: [Sip] B2B UA definition Ben Campbell
- [Sip] B2B UA definition Michael Thomas
- RE: [Sip] B2B UA definition Cullen Jennings
- RE: [Sip] B2B UA definition David R. Oran