Re: [sipcore] WGLC: draft-ietf-sipcore-rfc4244bis

"Andrew Allen" <> Tue, 21 June 2011 15:36 UTC

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Thread-Topic: [sipcore] WGLC: draft-ietf-sipcore-rfc4244bis
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From: Andrew Allen <>
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Subject: Re: [sipcore] WGLC: draft-ietf-sipcore-rfc4244bis
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Seems I missed the WGLC deadline by a day or so but here are the
comments from my review:


Section 5


"mp": The hi-targeted-to-URI represents a user other than the

 user associated with the Request-URI in the incoming request

  that was retargeted.

The term "user" here is confusing. Does it mean the human user (who
might have multiple AoRs/URIs which may or may not be known to the
retargeting proxy as AoRs/URIs that all map to the same human user)?
When retargeting is the proxy supposed to assess whether the new target
URI represents the same human user or not in order to determine whether
to include the "mp" parameter or not? I'm not sure what terminology
would be best but I think "user" is likely to cause confusion.

The above issue also reoccurs in section 7


Section 15

"Entities that have not implemented this specification MUST ignore these
parameters"?  We can't make any normative requirements on entities that
have not implemented this specification! Therefore the MUST should be
removed. I think you mean to state that according to RFC 3261 and RFC
4244 entities that are not compliant with this specification will ignore
these parameters.



There is a backward compatibility concern which I think should be
addressed. With 4244bis the URI in the Request-URI is now clearly to be
included in the History-Info when the Request-URI is replaced by the
Contact address. This was not the case in RFC 4244 where in many (if not
most) implementations rewriting the request-URI with the Contact was not
considered retargeting. Some existing UA implementations may have
assumed that the last History-Info entry cannot be their own Contact
Address but will always be their AoR. For example a UA may only look at
the next highest History-Info header field from the bottom most one in
order to determine whether the call arrived as a result of forwarding or
not from within their home domain and what the URI was that it was
forwarded from. Since outside the home domain of the UA up to now the
use of History-Info has not been deterministic some UAs may have only
looked at the last couple of History-Info header fields in order to
determine what happened to the request after it arrived within their
domain. In these kinds of scenarios having a proxy now add an additional
History-Info header field (for the rewriting of the Request-URI to the
Contact) in 4244bis may break the logic of such UAs. I am not saying we
shouldn't do this but I think some text about such possible problems
with existing implementations should be indicated in the backwards
compatibility section.


Section B.1
In this example, the Office and Home are not the

   same AOR as, but rather different AORs that have

   been configured as alternate addresses for Bob in the proxy.  In

   other words, Office and Bob are not bound through SIP Registration

with Bob's AOR.


The opportunity is missed to explain here that this means that the "rc"
parameter is not added. I think it would help to understand if that was






INVITE   should be INVITE





Request-URI for the ACK looks wrong to me shouldn't it be bob@





The URI in the Request-URI and the URI in the bottom most History-Info
header field are not the same (R-URI = office@ and H-I =
office@ These should be the same - suggest change R-URI to
office@ so as to avoid need to change H-I in the other flows
and also since is Alice's UA!!.





Again Request-URI for the ACK looks wrong to me shouldn't it be



Examples in B.2 and B.3 do not have the same level of detail as in B.1
or RFC 4244.




Last paragraph of 10.1 .2 "compenent" should be "component"

First and 2nd paragraph of 10.3 "add an hi-index"/"adds an hi-entry"
should be "a" not "an"





From: [] On
Behalf Of Paul Kyzivat
Sent: Sunday, June 05, 2011 7:34 PM
To: SIPCORE (Session Initiation Protocol Core) WG
Cc:; SIPCORE Chairs; Robert
Subject: [sipcore] WGLC: draft-ietf-sipcore-rfc4244bis


[as co-chair]

The current editor of draft-ietf-sipcore-rfc4244bis believes that the
document has no remaining technical issues, and is ready for evaluation.
Today, we are starting a two-week working group last call period. This
last call period ends on Sunday, June 19.

The latest version of the document can be retrieved here:

Any comments on the document should be sent to the SIPCORE mailing list.


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