RE: [Sip] B2BUA & Max-Forwards

["Mary Barnes" <mbarnes@nortelnetworks.com>]

I agree with Jonathan.  As mentioned earlier this week apparently, there is
already work underway by some individuals to write an informational draft
documenting BBUA scenarios/call flows. 

I'll keep my fingers crossed that the existence of such a document can save
us from another round of B2BUA discussions again in 3 months. 

Regards,
Mary.

-----Original Message-----
From: Jonathan Rosenberg [mailto:jdrosen@dynamicsoft.com]
Sent: Friday, December 06, 2002 12:59 AM
To: Pete Cordell
Cc: David R. Oran; Dean Willis; sip@ietf.org
Subject: Re: [Sip] B2BUA & Max-Forwards




Pete Cordell wrote:
> Dave,
> 
> To save your disagreeableness, can we say something like:
> 
> "A B2BUA MUST perform loop prevention.  One way to do this is to propagate
> the Max-Forwards header from the incoming request to the outgoing request
in
> the same way that a proxy does."

A statement like this is completely out of scope for rfc3261. It might 
be a reasonable statement to make in some kind of application document 
that describes a particular type of b2bua. However, it makes no more 
sense to say this in RFC 3261 as it would be to discuss the ways in 
which to build a focus or a 3pcc controller (both of which are also 
informational, by the way).

I can't resist pointing out that much of this is deja vu. Folks may 
recall heated discussions in Adelaide, where there was a bof (I think) 
that wanted to have a working group to specify SIP to H.323 conversion. 
THe same arguemtns that were made there are being made here; its an 
application level issue, there are many ways to do it, don't stifle 
creativity, etc. In fact I recall that Dave was, as always, quite 
vociferous on these points.

The eventual conclusion in the h323/sip conversion case was to write an 
INFORMATIONAL RFC that documents reasonable practices in building such a 
device. I believe the same logic and conclusions apply here. If folks 
have a particular type of b2bua application they are fond of, please 
feel free to write up your implementation advice and I am sure sipping 
would consider whether or not it would make a useful informational RFC.

However, it is completely inappropriate to ever make such application 
logic normative, and even more inappropraite for such wording to be in 
rfc3261.

Anyway, I too am tired of this thread. I think, in fact, there is 
"rough" consensus to remove the definition of b2bua entirely from 
rfc3261 in its next revision (which is quite some time in the future 
anyway). However, I'll let the chairs decide that.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
jdrosen@dynamicsoft.com                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
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