Subject: [Sip] RE: Open Issue #23: dynamic PT reuse

From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 7 Sep 2001 15:39:17 -0400

It has been two weeks since I posted this note. The resolution described
below was agreed to at IETF 51. There was no comment on my note, so I will
now assume list consensus exists as well. As such, this issue is closed.

Thanks,
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

> -----Original Message-----
> From: Jonathan Rosenberg 
> Sent: Wednesday, August 22, 2001 6:43 PM
> To: [email-masked]'
> Subject: Open Issue #23: dynamic PT reuse
> 
> 
> Issue:
> 
> Currently, bis says that if you use a dynamic PT once, you 
> can't reuse it again for a different codec in a re-invite. In 
> other words, lets say A invites B using GSM codec, dynamic PT 
> number 88. Then A re-invites, changing that stream to use 
> AMR, with PT 97. Now, A re-invites once more. If it wants to 
> use a codec other than GSM, it cannot use PT 88. Is that a problem?
> 
> Points of discussion:
> 
> The reason for this is synchronization of the media and 
> signaling. You absolutely cannot reuse a PT for a different 
> codec until any packets using that PT have been guaranteed to 
> have exited the network. Rather than worry about figuring out 
> a number for this, we just disallow reuse. 
> 
> The result is that you cannot cycle through more than 127 
> codecs in one SIP call. This is a reasonable restriction, IMHO.
> 
> Proposal:
> 
> keep this restriction.
> 
> There was consensus on this at IETF 51. 
> 
> -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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