Subject: stateful proxy

From: Ashok Khuntia <[email-masked]>
Date: Mon, 16 Aug 1999 09:15:37 -0500 (CDT)

I got a question. Does a stateful proxy server keep CALL STATE information or it keeps only the transaction state information? If it keeps the call state information, where can I get more information on that?

Thanks in advance.

Ashok

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From: "Adam B. Roach" <[email-masked]>
Date: Mon, 16 Aug 1999 11:47:35 -0500 (CDT)

>I got a question. Does a stateful proxy server keep CALL STATE 
>information or it keeps only the transaction state information? 
>If it keeps the call state information, where can I get more 
>information on that?

There is (understandably) a lot of confusion about this topic. As
defined in RFC2543, a stateful proxy keeps *transaction* state
information. (Read the first and last paragraphs of section 12.3 
carefully).

We've been calling the variety of proxy that keeps *call* state
information "call stateful proxies."

Exactly how much state you keep, and how long you keep it, is heavily
dependant on your particular application. For most of the applications
I have been examining (largely dealing with value added services), the
proxies will probably want to keep the same sort of information as a 
UAC/UAS, for the entire duration of the call.

To support this type of state in the proxy, there is a proposed extension
(draft-ietf-mmusic-sip-session-timer-02.txt); its purpose is to allow
proxies to free resources if the call terminates abnormally (e.g. without
the proxy being told).

--
Adam Roach, Ericsson Inc. |  Ph: +1 972 583 7594 | 1010 E. Arapaho, MS L-04
[email-masked]   | Fax: +1 972 669 0154 | Richardson, TX 75081 USA