Subject: RE: [SIP] separate SIP and stream addresses

From: "Culpepper, Bert" <[email-masked]>
Date: Tue, 29 Aug 2000 16:12:07 -0500

See comments below...

> -----Original Message-----
> From: Chris Durand [mailto:[email-masked]]
> Sent: Tuesday, August 29, 2000 4:40 PM
> To: [email-masked]'
> Subject: [SIP] separate SIP and stream addresses
> 
> 
> I'm new to SIP and want to make sure I understand how addressing of the
> streams is done. In particular, I want to check that it is not required
that
> the audio be routed to the same IP address as the SIP messages.
> For example if I want all SIP messages to be sent to 192.168.200.1, but I
> want the audio for a particular call to be sent to 192.168.200.5, port
3456
> , is it legal to do the following:
> 
> C->S:	INVITE sip:[email-masked] SIP/2.0
> 	Via: SIP/2.0/UDP some.server.com
> 	From: 192.168.200.1
> 	To: Test <sip:[email-masked]>
> 	Call-ID: [email-masked]        
> 	CSeq: 1 INVITE
> 	Contact: 192.168.200.1
> 	Subject: Send audio there, no here.
> 	Content-Type: application/sdp
> 	Content-Length: ...
> 
> 	v=0
> 	o=- 53655765 2353687637 IN IP4 192.168.200.1
> 	s=Please send audio here.
> 	t=3149328600 0
> 	c=IN IP4 192.168.200.5			<---- address to send RTP
packets to
> 	m=audio 3456 RTP/AVP 0 3
> 	a=rtpmap:0 PCMU/8000
> 	a=rtpmap:3 GSM/8000
> 
> Note that the address in "From"/"Contact" is different from the address in
> "c=". Is this the proper way to do it?

Yes.  In fact, you can send the two media types to different destinations
with the following
SDP.
	v=0
	o=- 53655765 2353687637 IN IP4 192.168.200.1
	s=Please send audio here.
	t=3149328600 0
 	m=audio 3456 RTP/AVP 0
	c=IN IP4 192.168.200.5		<---- address to send G.711 RTP
packets to
	a=rtpmap:0 PCMU/8000
 	m=audio 3456 RTP/AVP 3
	c=IN IP4 192.168.200.6		<---- address to send GSM RTP
packets to
	a=rtpmap:3 GSM/8000

> Thanks
> 
> 
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