After I saw Robert's posting on branch for a stateless proxy, I thought this
related question may also be relevant at this time since it remained
un-answered the first time I posted it.


-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Arunachalam
Venkatraman
Sent: Friday, August 23, 2002 11:00 AM
To: Sip-Implementors
Subject: [Sip-implementors] To Tag idempotence for stateless UAS


In 8.2.7 of RFC3261, it is stated that
>>>
To header tags MUST be generated for responses in a stateless
         manner - in a manner that will generate the same tag for the
         same request consistently.  For information on tag construction
         see Section 19.3.

<<<<


This would suggest that the Tag be generated in a deterministic manner based
on request parameters.
However, in 19.3, it is stated that the tag "MUST be globally unique and
cryptographically random with at least 32 bits of randomness"

These requirements appear to be at odds with each other.

The need to make the Tag idempotent in a response is obvious. Otherwise,
retransmission of a request will elicit a different response from that sent
previously. If both the resposes are received by the UAS with different
tags, the request will appear to have forked.

The issue is that if the tag is generated randomly and not in a
deterministic manner, the tag cannot be idempotent for the request.

What gives?

Venkat

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