Subject: Call-Leg identification

From: [email-masked]
Date: Mon, 17 Jan 2000 13:15:02 +0530

Hi,
     The call-leg of a SIP message is identified by the call-id, remote
address and the local address. However, since the call-id is unique for a
call-leg, wouldn't a Call-Id comparison suffice to check if two messages
belong to the same Call leg ? Is my assumption about the Call-Id being
unique for a call-leg correct ? I need to do this comparison for stopping
retransmissions of response messages.

Binu

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From: Sunitha Kumar <[email-masked]>
Date: Mon, 17 Jan 2000 10:32:14 -0600

The CallLeg is identified by the CallId, and CSeq number.

SIP messages belonging to the same transaction have the same CallId. But,
can have different CSeq numbers.  So, inorder to stop retransmissions, you
would probably have to check for both CallId, and CSeq number to be the
same, which is inessential, the CallLeg.

Hope that helps
sunitha

--
Sunitha Kumar
Software Engineer
Vovida Networks
(408) 957 - 6374

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From: Jonathan Rosenberg <[email-masked]>
Date: Mon, 17 Jan 2000 12:21:10 -0500

Sunitha Kumar wrote:
> SIP messages belonging to the same transaction have the same CallId.
> But, can have different CSeq numbers. 

This is incorrect.

A call is a collection of call-legs. A call-leg is the combination of
remote and local addresses (which include the tags) and Call-ID, but NOT
the CSeq. Within a call leg, each transaction has a different CSeq. The
CSeq space is within the call leg.

-Jonathan R.
-- 
Jonathan D. Rosenberg                       200 Executive Drive
Chief Scientist                             Suite 120 
dynamicsoft                                 West Orange, NJ 07052
[email-masked]                     FAX:   (732) 741-4778
http://www.cs.columbia.edu/~jdrosen         PHONE: (732) 741-7244
http://www.dynamicsoft.com

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From: Sunitha Kumar <[email-masked]>
Date: Mon, 17 Jan 2000 11:40:23 -0600

Thanks Jonathan, for correcting me.

sunitha.

--
Sunitha Kumar
Software Engineer
Vovida Networks
(408) 957 - 6374