Subject: RE: [Sipping] Last Call: draft-ietf-sipping-dialogusage (Multiple Dialog Usages in the Session Initiation Protocol) to Informational RFC

From: "Ian Elz \(CV/ETL\)" <[email-masked]>
Date: Fri, 4 May 2007 18:11:43 +0200

I have noted the last call on this draft and the proposal to raise the
draft to Informational RFC status.

While this draft gives a very detailed view of the issues relating to
multiple dialog usage it also provides recommendations in areas where
there is no or little examination of specific areas.

In section 5.7 Replacing Usages there is the statement:

     ...the interactions between Replaces and multiple dialog usages
   have not been well explored.  More discussion of this topic is
   needed.  Implementers should avoid this scenario completely.  

I do not believe that an informational RFC should include
recommendations based upon little or no examination or lack of
understanding of specific areas.

The draft as a whole recommends avoiding multiple dialog usage as it may
be difficult to implement the required logic while only offering
alternatives in simple network cases. With new ietf draft documents
being published which highlight the impact on the network of B2BUA nodes
I believe that there should be some examination of the impact of
proposing that each new dialog usage be on a new dialog will have on
networks which include B"B User Agents. 

If recommendations are made which influence vendors to only develop user
agents which support single usage dialogs we may come to the situation
where B2BUAs cannot be used in the network. This would prevent specific
security measures such as identity hiding from untrusted networks as it
would not be possible to map Contact headers. It would also prevent
topology hiding. Preventing both of these measures could result increase
the prevalence of denial of service and other attacks on the network.

While the proposals in this draft may prove to be a worthwhile addition
to the knowledge of dialog and usage handling in the internet I believe
that raising this draft to RFC status before the relevant studies have
been undertaken in the associated areas, which are currently being
studied, is premature.

Ian Elz

Office: + 44 24 764 35256
gsm: +44 7801723668
[email-masked]

------------------------------------------------------------------------
-
Message: 3
Date: Thu, 26 Apr 2007 09:39:45 -0400
From: The IESG <[email-masked]>
Subject: [Sipping] Last Call: draft-ietf-sipping-dialogusage (Multiple
	Dialog  Usages in the Session Initiation Protocol) to
Informational
	RFC 
To: IETF-Announce <[email-masked]>
Cc: [email-masked]
Message-ID: <[email-masked]>

The IESG has received a request from the Session Initiation Proposal 
Investigation WG (sipping) to consider the following document:

- 'Multiple Dialog Usages in the Session Initiation Protocol '
   <draft-ietf-sipping-dialogusage-06.txt> as an Informational RFC

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action.  Please send substantive comments to the
[email-masked] mailing lists by 2007-05-10. Exceptionally, 
comments may be sent to [email-masked] instead. In either case, please 
retain the beginning of the Subject line to allow automated sorting.

The file can be obtained via
http://www.ietf.org/internet-drafts/draft-ietf-sipping-dialogusage-06.tx
t

IESG discussion can be tracked via
https://datatracker.ietf.org/public/pidtracker.cgi?command=view_id&dTag=
14041&rfc_flag=0

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From: "Ian Elz \(CV/ETL\)" <[email-masked]>
Date: Fri, 4 May 2007 18:11:43 +0200

Ian Elz