Subject: [Sip] bis draft: Pre-existing Route headers

From: "Drage, Keith (Keith)" <[email-masked]>
Date: Fri, 7 Dec 2001 20:17:19 -0000

Section 8.1.1.7 of the bis draft (lines 948 through 952) appears to be the
text that allows pre-existing Route headers to be used in the initial
transaction of a dialogue, or in a stand-alone transaction.

	"8.1.1.7 Request-URI The initial Request-URI of the message SHOULD
be set to the value of the URI in the To field. One notable exception is the
REGISTER method; behavior for setting the Request-URI of register is given
in Section 10. Another exception is the case of pre-existing Route headers;
in that case, the procedures of Section 12.2.1.1 as they pertain to the
Request- URI are followed, even though there is no dialog." 

A set of Route headers created using the Record-Route mechanism carries the
mechanism to ensure that when the route traverses a spiral, all the URLs in
the Record-Route headers are unique, and therefore that the set of Route
headers is also unique.

There should be a similar pre-condition for a set of pre-existing Route
headers. I would suggest text of the form:

	"The procedures for the creation of the Record-Route header ensure
that when a spiral is negotiated, the URLs for the set of resultant Route
headers are all unique. The mechanisms for creating a set of pre-existing
Route headers are outside the scope of this document, but such mechanisms
MUST ensure that any set of pre-existing Route headers consists only of
unique URLs even when it is intended that the route should spiral."

As to location it could possibly go with 8.1.1.7 or inserted in the text for
the Route header, with some additional introductory text.

Any comments? Is this acceptable?

Keith
Keith Drage
Lucent Technologies
Tel: +44 1793 776249
Email: [email-masked]

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