[AG-TECH] room node certificates

Colin Perkins csp at csperkins.org
Sun Oct 5 13:22:31 CDT 2003


On Wednesday, Oct 1, 2003, at 16:22 Europe/London, Jay Beavers wrote:
> The "first issue", using CNAME to link multiple streams to a logical
> sender, is very clear from the spec.  In the "second issue", AKA 
> reusing
> a CNAME between multiple hosts, it's possible that you'll run into
> interoperability problems.  It's a reasonable assumption from reading
> the spec that you could reuse CNAMES between multiple hosts, there's
> nothing in the spec which says you can't do this.  It's also a
> reasonable assumption from reading the spec that a CNAME bound to a
> specific host.  There's also nothing in the spec to say this isn't true
> and at least to me this is implied by the recommended value for CNAME 
> of
> "user at host".  Because of the ambiguity here, you may run into problems
> between two spec compliant implementations of the same standard.

The second issues is not entirely clear from the spec, although the 
only scenario I would expect to be problematic is if a receiver is 
tracking source addresses and comparing them to the CNAME IP address. 
That's not guaranteed to work anyway though, because of multi-homed 
hosts, NAT boxes, IPv4-to-IPv6 and multicast-to-unicast translators, 
mixers, etc.

> I like your paper below, I think it is a good analysis of the issues 
> you
> run into using Rtp for shared applications.  I also feel there are a 
> few
> additions you can make within the Rtp protocol (a SDES PRIV extension
> for CHANNEL as noted below, Reed-Solomon FEC, NAK ARQ, and PGMCC) that
> are within the purview of the Rtp spec that address your concerns :-)
> The end result is one network stack which can handle streaming a/v data
> or shared state data depending upon behavior properties which are set 
> on
> a per Stream or PayloadType basis while exposing an Api to application
> writers which is consistent between media types.

How would you solve the timing issues? The implied RTP playout model 
isn't really suited to shared workspace applications.

Cheers,
-- 
Colin Perkins
http://csperkins.org/




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