> On April 23, 2014, 4:13 p.m., Mark Michelson wrote:
> > /trunk/channels/chan_sip.c, lines 22992-22996
> > <https://reviewboard.asterisk.org/r/3438/diff/1/?file=57236#file57236line22992>
> >
> >     RFC 3261 section 16.7, bullet point 2 states:
> >     
> >     "...if the response is a provisional response with status codes 101 to 
> > 199 inclusive (i.e., anything but 100), the proxy MUST reset timer C..."
> >     
> >     This else case needs to be modified to not execute if the response is a 
> > 100.
> 
> Matt Jordan wrote:
>     I think I agree with Mark here as well, and the RFC makes sense when it 
> says to not reset Timer C on a 100. There's no real need to reset Timer C in 
> that case, as that typically comes directly on the heels of the transmitted 
> INVITE request.
> 
> Olle E Johansson wrote:
>     I am not sure. What's the use case for not doing it on 100. I understand 
> why a proxy should not react to a 100, since it's hop by hop, but for a UA I 
> don't see the point of your comment.
> 
> Matt Jordan wrote:
>     I would guess it is for two reasons:
>     
>     (1) Timer C is started when the INVITE request is first processed. A 100 
> Trying received from who you just sent the INVITE request to is extremely 
> likely to happen very quickly, since the UAS should be sending the 100 Trying 
> on immediately receiving the INVITE request. Resetting the timer on the 100 
> Trying doesn't really offset the timer by much.
>     
>     (2) More specifically, this probably relates to stateful proxies not 
> forwarding 100 Trying messages. Since we aren't a proxy, that's probably of 
> less impact in this case.
>     
>     I'd bypass resetting the timer on a 100 for two reasons:
>     (1) It doesn't add much value to reset the timer in the first place on a 
> 100
>     (2) It precludes (yet another) "you don't follow the RFC" bug report :-)

This doesn't make sense for a UA. We should reset it for any responses. By 
implementing this timer and calling it Timer C and not AstTimer Q we break the 
RFC any way. ;-)


- Olle E


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On May 16, 2014, 2:32 p.m., Olle E Johansson wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviewboard.asterisk.org/r/3438/
> -----------------------------------------------------------
> 
> (Updated May 16, 2014, 2:32 p.m.)
> 
> 
> Review request for Asterisk Developers.
> 
> 
> Repository: Asterisk
> 
> 
> Description
> -------
> 
> SIP Timer C is defined for proxys that forward messages. In some ways, we 
> forward calls. It is activated when we receive a 100 trying and wait for any 
> other message. If that's not received, timer C triggers and cancels the call 
> attempt.
> 
> This is required in an interoperability test I'm working with.
> 
> Red dots will be handled in the way they deserve.
> 
> 
> Diffs
> -----
> 
>   /trunk/configs/sip.conf.sample 414046 
>   /trunk/channels/sip/include/sip.h 414046 
>   /trunk/channels/chan_sip.c 414046 
>   /trunk/CHANGES 414046 
> 
> Diff: https://reviewboard.asterisk.org/r/3438/diff/
> 
> 
> Testing
> -------
> 
> Passed interoperability testing with funky test tool.
> 
> 
> Thanks,
> 
> Olle E Johansson
> 
>

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