Subject: [Sipping] Record-Route clarifications in bis-03

From: "Sudharsana krishnan P" <[email-masked]>
Date: Thu, 21 Jun 2001 10:43:50 +0530

All,
Sorry about the incomplete mail..

16.4.1 - bis-03
"If a local outbound proxy wishes to remain on the SIP messaging 
path for a call leg, it MUST record-route using the procedures above."

"A UA which uses a local outbound proxy, and attempts to send a 
subsequent request in a call leg with a route set, SHOULD use the 
procedures in Section 16.4. However, in some instances, a UA may
not be capable of DNS, and therefore may not be able to follow those
procedures. In this case, the UA MAY send the request to its local
outbound proxy. In this case, it MUST NOT remove the top Route header. 
It sets the Request-URI to the same value it used for the initial request, 
and sends it to its local outbound proxy."

There seem to exist a possibility that such an outbound proxy 
ends up routing a Sip request to itself, when the 
UA is not capable of DNS and behaves as documented.
Did I miss something here ??

--
Best Regards,
Sudharsana krishnan

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---

From: Vijay Gurbani <[email-masked]>
Date: Thu, 21 Jun 2001 09:00:37 -0500

> Did I miss something here ??

No; such a possibility is real, and I have seen it at the bakeoffs and
the UAs in my lab.

The easiest way to deal with this is to have the proxy recognize that the
topmost Route is for it, pop it and discard it, and use the next Route entry 
to further route the request. 
 
Regards,

- vijay
-- 
Vijay K. Gurbani  vkg@{lucent.com,research.bell-labs.com,acm.org}
Internet Software and eServices Group 
Lucent Technologies/Bell Labs Innovations 263 Shuman Blvd., Rm 1A-413
Naperville, Illinois 60566     Voice: +1 630 224 0216   Fax: +1 630 713 0184