Subject: [Sip] subnot-etags: suppressing NOTIFY interactions with SBCs and other middleboxes

From: Aki Niemi <[email-masked]>
Date: Tue, 31 Jul 2007 10:08:29 +0300

Hi all,

This is a potential show-stopper issue that Rohan brought up in the SIP
WG session last week.

Currently, subnot-etags offers two modes of operation. In the first, the
body of the SUBSCRIBE-generated NOTIFY is suppressed, and in the other,
the entire NOTIFY is suppressed, and a new response 204 (No
Notification) is generated instead.

The latter is a considerable change to how SIP events works, and might
cause a middlebox that tracks the SIP dialog to basically barf, thinking
the dialog expires when it in fact gets refreshed.

Do folks think this is a problem? It would be great if some SBC vendors
could check what their implementation does with SUBSCRIBE dialogs.

Personally, I'd hate to hack around boxes that people claim are doing
something fishy. But if this is a real problem, then subnot-etags would
basically need to be reduced to just suppressing bodies of NOTIFYs.

Cheers,
Aki

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From: Paul Kyzivat <[email-masked]>
Date: Tue, 31 Jul 2007 07:36:59 -0400

I don't think this is a real problem. It is a *change*, no worse than 
other changes we make from time to time. It won't bother the sorts of 
middleboxes (proxies) that we have clear standards for. If it bothers 
B2BUAs then they will need to learn how to deal with it.

	Paul

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From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 31 Jul 2007 09:21:58 -0400

I'm worried that, if you eliminate suppression of NOTIFY itself, the 
primary value of this draft (reduction of message traffic) is lost. I'd 
like to keep this capability if we can.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                   600 Lanidex Plaza
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