Subject: [SIP] RE: [Simple] Difference between a SUBSCRIBE and a re-SUBSCRIBE

From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 1 Jun 2001 03:55:33 -0400

> -----Original Message-----
> From: Robert Sparks 
> Sent: Tuesday, May 29, 2001 10:11 AM
> To: 'Christian Jansson'; David Simons; Jonathan Rosenberg
> Cc: [email-masked]'
> Subject: RE: [Simple] Difference between a SUBSCRIBE and a 
> re-SUBSCRIBE
> 
> 
> You are correct that a receiving agent can only expect
> increasing CSeqs due to the opportunity for intervening
> proxies to consume messages (with a 407 for example).
> 
> The remaining motivation for increasing by 1 on the sending
> side, as I understand it, is preserving CSeq space.

Thats not a huge motivation, since the space is 2^31, which is pretty big
for a single call leg.

To be honest, the main motivation for contiguous increments was to provide
contiguous increments at UAS, but this was before we (or, at least I)
realized that an intermediate 407 fouled it all up. So, there is no real
large motivation remaining, excepting that a UA can probably use it to
detect a crash and restart condition on the remote side (a large gap in
sequence numbers).

-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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