RE: [MMUSIC] RE: alternate RTP profiles in SDP offer/answer

["Dan Wing" <dwing@xxxxxxxxx>]

> > But unless the endpoint understands the grouping syntax and
> > semantics, the new syntax and semantics are invisible to such
> > an endpoint.  I mean, that is the problem with RFC3388 -- if
> > you send RFC3388 SDP to an endpoint that doesn't understand
> > RFC3388 it will parse the SDP following normal SDP rules
> > which say each m= line is a separate RTP session.
> 
> This is a fundamental problem with FID semantics defined in 
> RFC3388 and sec 8.4.2 describes how to address this issue.
> 
> Sec 8.4.2 of RFC3388 suggests that the offer re-try without 
> "group".  That may not look good, but is not too bad either. 

That probably works alright with RTSP, but doesn't work with SIP forking due
to HERFP (Heterogeneous Error Response Forking Problem).

-d


> Those end points which crash when they look at transport 
> overloaded "m=" lines are anyways faulty s/w implementations 
> and it is unlikely that majority of deployed s/w is unstable 
> to such an extent. And with the (majority of good) end points 
> that do not crash, it is possible to continue the session.
>  
> In any case, not supporting the fallback approach suggested by RFC3388
> is risky.
> 
> > -d
> >