Subject: [SIP] RE: [Sip-implementors] Query on Multicast transmission in SIP

From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 29 May 2001 16:12:56 -0400

> -----Original Message-----
> From: Sudharsana krishnan P [mailto:[email-masked]]
> Sent: Monday, May 14, 2001 5:15 AM
> To: [email-masked]
> Cc: SipWg (E-mail)
> Subject: [Sip-implementors] Query on Multicast transmission in SIP
> 
> 
> All,
> 
> I need some help in understanding the following:
> 
> Section 10.0.1 bis02 says
> "Servers do not respond to CANCEL requests received via 
> multicast to avoid request implosion. A proxy or UAC 
> SHOULD send a CANCEL on receiving the first 2xx,
> 401, 407 or 6xx response to a multicast request."
> 
> The above statement seems to imply that the multicast CANCEL would end
> up transmitted a total of 11 times (by the UAC/Proxy) always.
> Is this the intended behaviour ? 

Ah, the joys of reliable multicast.

That is the way it works now, yes. Ugly. Since CANCEL needs to be received
by all downstream servers in the multicast group, there is no other way to
do it without real reliable multicast.

> 
> If not, text(caveat) should be inserted to state that the UAC/Proxy 
> may stop retransmissions (of cancel) after,
> say an implementation specified maximum.

I'd really rather not special case it, so it seems that the specified
default of 11 is fine.

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

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