Subject: RE: [SIP] Bug in 2543bis-02 re: Record-Route

From: "Emami-Nouri, Mohsen" <[email-masked]>
Date: Wed, 20 Dec 2000 14:28:14 -0800

When a UA crashes after the call is stablished, and then it comes back and
wants to cancel or bye the call , since it has not got any route information
for that call-leg, so the UA can not send this request through the proxies ,
which insisted to be visited by any request belonging to the same call. So
my question is how this could be solved by proxies adding RR to each request
blonging to the same call.

-----Original Message-----
From: Vijay Gurbani [mailto:[email-masked]]
Sent: Wednesday, December 20, 2000 12:38 PM
To: Emami-Nouri, Mohsen
Cc: [email-masked]
Subject: Re: [SIP] Bug in 2543bis-02 re: Record-Route

"Emami-Nouri, Mohsen" wrote:
> 
> Talking roubestness, proxy adding itself to each requests would only take
> care of responses going the right route, but not any new request after an
> UA  crashed. 

I suspect not; the responses will follow the Via list, not the Route list.

> For that the route ninformation needs to get persistant, so that
> the UA also after a crash still has the route information, am I right?

Hence the need for every proxy to include a R-R so that a crashed UA can
resurrect the Route list from the R-R headers in the request it got after
rebooting.

- 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

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From: Vijay Gurbani <[email-masked]>
Date: Thu, 21 Dec 2000 10:32:42 -0600

"Emami-Nouri, Mohsen" wrote:
> wants to cancel or bye the call , 

The assumption that a UA after a reboot needs to BYE or CANCEL a call 
implies that the UA saved state in persistent store before it crashed, right? 
If that is the case, the UA presumably can also save the Route 
information as part of the call state, so when it comes back up after a 
reboot, it knows the Route list?  Or am I missing something?

> since it has not got any route information for that call-leg, so the UA 
> can not send this request through the proxies , which insisted to be 
> visited by any request belonging to the same call. So my question is how 
> this could be solved by proxies adding RR to each request blonging to the 
> same call.

Adding R-R on every request helps UAS that may crash, reboot, and receive a 
re-INVITE for the call; the re-INVITE will have R-Rs added by upstream 
proxies from which the UAS can resurrect the Route list.

There are some postings on the SIP mailing list discussing the genesis of
this addition in 2000q2 SIP archives.

Regards,

- vijay