> -----Original Message-----
> From: Magnus Westerlund [mailto:[EMAIL PROTECTED]
> Sent: Tuesday, February 26, 2008 6:01 AM
> To: Phelan, Tom
> Cc: Dan Wing; [EMAIL PROTECTED]; 'dccp' working group;
> Colin Perkins
> Subject: Re: [dccp] DCCP-over-UDP [was
> draft-phelan-dccp-natencap-00.txt]
>
> Hi,
>
> There has been a lot of talk in this thread about DNS. I want
> a solution
> that works without DNS. If one uses SIP or RTSP to establish
> a media pat
> using DCCP. In most cases one do include the explicit IP
> address rather
> than the FQDN.
> Thus no DNS queries etc. I think something that makes
> this work on the same port is desirable.
I agree that we want something that doesn't require DNS.
However, SIP and RTSP (which use SDP) don't require DNS. The SDP indicates
the transport protocol (today, UDP) and port. I expect with DCCP you could
indicate the transport protocol (DCCP-RAW, DCCP-UDP) and port. Syntax would
be something vaguely like:
v=0
o=alice 2890844526 2890844526 IN IP4 client.atlanta.example.com
s=
c=IN IP4 client.atlanta.example.com
t=0 0
m=audio 49170 RTP/AVP/DCCP 0
a=dccp-raw 49172
where the "m=audio" line indicates RTP-over-DCCP-over-UDP is on UDP port 49170
and "a=dccp-raw" indicates that same profile (RTP/AVP) is available on DCCP
port 49172.
I expect that draft-ietf-mmusic-sdp-capability-negotiation would have a
prettier and more useful way of expressing this sort of thing, especially if
there is a desire to also fall back to RTP-over-UDP (without any DCCP).
Using DNS SRV, the same thing would be expressed as:
_foobar._dccp-udp SRV 0 0 49170 client.atlanta.example.com.
_foobar._dccp SRV 0 0 49172 client.atlanta.example.com.
-d
