> -----Original Message-----
> From: Brett Tate [mailto:[EMAIL PROTECTED]]
> Sent: Monday, May 14, 2001 5:06 PM
> To: 'Paul Kyzivat'; [EMAIL PROTECTED]
> Subject: RE: [Sip-implementors] When does reinvite take effect?
>
>
> > I have some general questions about reinvite:
> >
> > - exactly when do the changed media descriptions take effect?
>
> When send the re-INVITE, should listen based on the
> re-INVITE and prior SDP. The positive/negative
> response will indicate which definition should
> remain active.
Even if the INVITE succeeds, and has changed the port or address, you should
listen on the old one until packets appear on the new.
>
> When providing the change in a 200 response, should
> listen based on the 200 response and prior SDP
> until the ACK is received or starting to receive
> packets based upon the new SDP.
Even when the ACK comes, you should still be waiting for packets on the old
IP/port until media comes on the new.
Note that there is no issue for changes in codecs or media streams, as these
are explicitly signaled in the RTP stream.
>
> >
> > - isn't there a period of ambiguity when it is possible that
> > either the old or the new descriptions might be operative?
>
> Yes, if you are using the same connection address/port
> and did not hold between the media switch.
No, there is no ambiguity for the reason you point out below; its clear what
the codecs are. There would only be ambiguity if you attempt to reuse
dynamic PT numbers in a re-INVITE for a different codec. This is explicitly
disallowed, though.
>
> Note: the media packet will contain which codec is being
> used.
>
-Jonathan R.
---
Jonathan D. Rosenberg, Ph.D. 72 Eagle Rock Ave.
Chief Scientist First Floor
dynamicsoft East Hanover, NJ 07936
[EMAIL PROTECTED] FAX: (973) 952-5050
http://www.jdrosen.net PHONE: (973) 952-5000
http://www.dynamicsoft.com
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