Re: [Sip] SDP in unreliable 18x

["Salva Rey Calatayud" <salreyca@teleco.upv.es>]

Hi,

	see at end (again)

On 15 Mar 2002, at 19:53, Gonzalo Camarillo wrote:

> Hi,
> 
> Salva Rey Calatayud wrote:
> > 
> > Hi,
> > 
> >         please see inline at end,
> > 
> > On 7 Mar 2002, at 22:01, Jonathan Rosenberg wrote:
> > 
> > >
> > >
> > > Christer Holmberg wrote:
> > > >
> > > > Hi Bob,
> > > >
> > > > > >Now, does this mean I'm not allowed to send an SDP 
in an UN-reliable
> > > > > >18x? And, if I do, is it then not regardes as an answer?
> > > > >
> > > > > You are allowed to send SDP in an unreliable 1xx. 
However, it MUST be
> > > > the
> > > > > same as the SDP you will send in a 2xx. The key 
sentence is "That same
> > > > exact
> > > > > answer MAY also be placed in any provisional 
responses sent prior to
> > > > the
> > > > > answer."
> > > >
> > > > True. But, in this case the UAC is not allowed to send a 
new offer (eg
> > > > using
> > > > UPDATE) before it has received the final response.
> > >
> > > Right. The idea was to try and add a semblance of 
compatibility with
> > > existing implementations. We want everything to be mapped 
to a set of
> > > non-overlapping O/A exchanges. So, the idea is that the 
SDP in an
> > > unrealiable 18x, and the SDP in a 2xx, are just the same 
answer. THus,
> > > we maintain the property of everything being a series of O/A 
exchanges,
> > > but allow a single answer to be present in multiple sip 
responses.
> > >
> > > However, it is NOT allowed, to send an offer in INVITE, an 
answer in a
> > > reliable 183, and then repeat the answer in the next reliable 
183. Thats
> > > because the answer has to be 
in the first reliable response 
sent back,
> > > which is the first 183. The SDP in the second 183 would be 
illegal,
> > > since it would be an offer, and those can't go in responses 
after the
> > > first SDP.
> > 
> >         I don't quite understand why these new offer on th
> > e reliable 183
> > would be illegal. Isn't it conveyed on a reliable delivered 
message. I
> > thought that was the only condition for O/A exchanges. or is it 
that
> > it's only allowed one O/A exchange per transaction?
> > 
> 
> It is illegal to avoid glare conditions, where you could not refuse 
the
> offer in the provisional response even though you would have sent 
an
> UPDATE.
> 
> The update draft outlines when you can send an offer and how.

 I never mentioned the UPDATE method being used here. could 
you answer my question why a second 183 rel conveying a second 
offer is illegal? feel free to give references to sections in drafts.

In a couple of my questions you always refer me to the update draft 
and suggested that I should read it. What does it make you think I 
haven't? If everything was so clear in the drafts we wouldn't be 
needing at all this mailing lists. I am afraid that drafts are far from 
error-free documents. So, be gentler and try to give an answer to 
questions instead of making references to documents all the time. 
And one second question on this email : 

	How many lines in the update draft mention that a UAS can 
issue an UPDATE?

thanks and regards,
Salva
**********************************
Salvador Rey Calatayud,  M.Sc.
Siemens AG                       Room 53521
salreyca@teleco.upv.es           Munich, Perlach 
Phone number : +49-16095178051
**********************************


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