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

["Christer Holmberg" <christer.holmberg at ericsson.com>]

Hi Brett,

>>We will not define an option-tag for 199 support. 
>
>Since the working group has issue with using option-tag, I propose
something else be added to request to indicate that something along the
path supports and desires receiving 199.
>
>For instance, rfc4028 allows the UAC or proxy to include
Session-Expires.  A similar header (maybe generic one) could be defined
and optionally contain parameters (uac, proxy, etcetera); for 
>instance, "Desire-199:".

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.


>>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.

>>2) are proxies allowed to send 199 reliably?
>I wouldn't consider it a proxy since it is trampling upon another's
RSeq and dialog (depending upon 199's Record-Route and Contact).

I think it's rather clear that people don't want proxies to send proxy
originated 199 responses reliably. Or, does anyone have another opinion?


>>3) Assuming proxies are allowed to send 199 (see issue 1), are proxies
allowed to send 199 unreliably, even if 100rel is required?
>Concerning this and other non compliances, not sending the 199 would
likely be best to avoid violating rfc3261/rfc3262.

Ok. This is one of the issues still discussed.


>>4) Is it a MAY/RECOMMENDATION/SHOULD/MUST for UAS to send 199? 
>I prefer MAY.

Ok.

Thanks for your comments!

Regards,

Christer


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