Re: [Sip] 199: Staus and open issues after Dublin

["Brett Tate" <brett at broadsoft.com>]

Hi Christer,

Thanks for response.  Reply inline. 

> The group never discussed if there is any "issue" with 
> using an option-tag (e.g. if proxies are allowed to 
> insert values). The opinion was more that there is no 
> need for any sort of indication.

After Cullen mentioned the reason for it, I guess that I should stayed
at the microphone and re-iterated the reasons.

Sending 199 is useless overhead unless something along the path supports
and wants it.  

If UAC does not support 199, sending it might cause more harm than good.


> > > 1) Is a proxy allowed to send 199 in the first 
> > > place, or are only UASes allowed to do it?
> >
> > I have no issue with allowing it.  However the draft 
> > should likely provide guidance if originator of 199 
> > still considered a proxy or has morphed into UAS/b2bua when 
> > using another's To tag.  Depending upon interpretation of 
> > rfc3261 (and dropped packets), there are potential issues 
> > concerning Contact and Record-Route of the 199 (unless 
> > remember prior for inclusion within 199).  
> >
> > What should occur when INVITE 2xx received after proxy 
> > originated 199 with the same To tag?
> 
> I am not sure how that could happened. If the proxy received 
> a final response, which triggered the 199, I don't think it 
> will later receive an 2xx with the same To tag.

If no proxy steals another's To tag for originating a final INVITE
response, I agree.  I don't recall what rfc3261 and invfix recommend
concerning the abnormal situation from proxy and UAC perspectives.  I
was mainly just asking for conceptual reasons based upon the paragraph
prior to my question.  If it occurs, should the originator of 199 tag X
process the 2xx tag X like a UAC or proxy?
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