[SIPForum-discussion] Possible Spam : Re: 183 Session Progress without SDP

[Tomasz Zieleniewski]

Yes, I agree that this all is not very clear.
100 Trying is sent on the hop-by-hop basis 183 Session Progress
is sent end-to-end so one can imagine that, when UAC doesn't
support the 100rel extension, sending 183 Session Progress will
give higher probability that the transaction along the sip path
will move to Proceeding state. Anway I also think it shouldn't be done
this way.

- Tomasz


2009/4/11 Vivek Batra <Vivek.Batra at matrixtelesol.com>:
> If this is matter of not receiving 100 Trying, then 183 Session Progress
> (w/o SDP) can also be dropped in the network. Hence, I believe that
> retransmission should be achieved by adding reliability in provisional
> responses (using 100rel) instead sending the same provisional response
> without SDP and then with SDP.
> Anyway I am not very clear with the real world application of d'ing this.
>
> -----Original Message-----
> From: discussion-bounces at sipforum.org
> [mailto:discussion-bounces at sipforum.org] On Behalf Of Tomasz Zieleniewski
> Sent: Friday, April 10, 2009 7:14 PM
> To: Manish Aggarwal
> Cc: discussion
> Subject: Possible Spam : Re: [SIPForum-discussion] 183 Session Progress
> without SDP
>
> Hi All,
>
> I totally agree with Manish,
> One more thing that came to my mind was that gateway by sending this first
> 183 ASAP could assure that if for any reason originating UAC on the whole
> sip downstream path didn't receive the 100 trying response this will cause
> that this INVITE transaction will move to Proceeding state and there would
> no retransmissions.
>
> Cheers
> - Tomasz Zieleniewski
>
> 2009/4/9 Manish Aggarwal <maaggarwal at gmail.com>:
>> Multiple provisional responses is allowed as per the protocol spec.
>> This can be used to create an early dialogue.
>>
>> A UAS will send this, when its taking long time to process INVITE (and
>> before sending 200 OK).
>>
>> Have heard of this behavior before though.
>>
>>
>> -Manish
>>
>> On Thu, Apr 9, 2009 at 12:26 PM, nitin kapoor <nitinkapoorr at gmail.com>
>> wrote:
>>>
>>> Dear All,
>>>
>>> We are facing one problem where we are getting two 183 session for 1
>>> INVITE. UAC sending the INVITE to Switch and switch has forwarded the
>>> same invite to UAS. Then UAS first send the 183 Session progress
>>> without SDP and after 2 Sec its sends the another 183 Session
>>> Progress with SDP which is something i am not able to understand.
>>>
>>> 1) Can you please tell me on which cases UAS sends the two 183
>>> Session progress like this.( with SDP & without SDP)?
>>> 2) Is this the correct behaviour?
>>>
>>> I checked this on RFC3261 and another sip pdf but unable to search it.
>>>
>>> Please find the attached Traces.
>>>
>>> Thanks
>>> Nitin Kapoor
>>>
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>>
>>
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