[Freeswitch-users] Multiple 183 SDP Change Codecs - allowed?

Tue Jul 3 19:50:45 MSD 2012

Sorry, missed the pcap in the original message.  I'd try the NDLB
setting and see what happens.

Keep in mind what I said about the carrier and FAS...  While it's not
technically non-compliant behavior it reeks of either incompetence or
malice.

Generally speaking (in the SDP offer/answer model) as long as the
remote end's answer contains codecs in your offer it is valid answer
(even if there are several of them).

What happens if you remove either PCMA or PCMU from your INVITE (offer)?

On Tue, Jul 3, 2012 at 11:02 AM, Avi Marcus <avi at avimarcus.net> wrote:
> Indeed both are enabled... check the PCAP from the original message:
> http://ge.tt/7MpyBwJ
> It shows I'm offering in the original invite: audio 28380 RTP/AVP 8 0 9 101
> 13
>
> I remember this similar issue with 18x have a different codec than a 200 and
> Anthony said it was against the RFC but
> http://wiki.freeswitch.org/wiki/NDLB#NDLB-allow-nondup-sdp would allow that
> broken behavior.
> I'm wondering if this is the same thing if so what RFC to point the vendor
> to.
>
> Would there be a potential negative to turning on this NDLB setting?
>
> -Avi
>
>
>
> On Tue, Jul 3, 2012 at 5:50 PM, Steven Ayre <steveayre at gmail.com> wrote:
>>
>> Actually rereading the trace, it looks like you have both PCMU & PCMA
>> enabled on lines 39-40.
>> AviMarcus, Can you confirm your codec preferences to be sure?
>>
>> If so, it appears to only be comparing the codec in the 2nd SDP to the
>> codec that's been selected for the call, not to all the codecs enabled on
>> the profile. That does sound like a bug, unless there's some parameter set
>> that's intentionally causing that behaviour...
>>
>> -Steve
>>
>>
>>
>>
>> On 3 July 2012 15:46, Steven Ayre <steveayre at gmail.com> wrote:
>>>
>>> Looking at lines 75-78 you have PCMA enabled on FS as a codec option but
>>> not PCMU.
>>>
>>> When it goes to change to the PCMU codec it looks through the enabled
>>> codecs but doesn't find PCMU so hangs up the call with
>>> INCOMPATIBLE_DESTINATION.
>>>
>>> You need to add both PCMA and PCMU in your codec preferences.
>>>
>>> -Steve
>>>
>>>
>>>
>>>
>>> On 3 July 2012 14:38, Avi Marcus <avi at avimarcus.net> wrote:
>>>>
>>>> If so.. which I think is not.. is this a bug then in FS?
>>>>
>>>> http://pastebin.freeswitch.org/19423
>>>> You see from the first SDP that PCMU and PCMA were both options.
>>>> Then for the next SDP FreeSWITCH was only considering PCMU which was the
>>>> one that got chosen by the first SDP.
>>>>
>>>> Voxbeam claims it's not their fault.. is it?
>>>>
>>>> -Avi
>>>>
>>>>
>>>>
>>>> On Tue, Jul 3, 2012 at 4:26 PM, Kristian Kielhofner <kris at kriskinc.com>
>>>> wrote:
>>>>>
>>>>> Avi,
>>>>>
>>>>>   Multiple 18x responses that change the SDP are allowed.  I can't
>>>>> find the specific document text now but as a random guy on the
>>>>> internet (for whatever that's worth) I'm certain it is allowed.
>>>>>
>>>>>   A re-INVITE can't be sent from either side until the dialog has been
>>>>> established (200+ACK).  In a case where the UAC (caller) would like to
>>>>> update the session before it is established method UPDATE must be
>>>>> used.
>>>>>
>>>>> On Tue, Jul 3, 2012 at 1:04 AM, Avi Marcus <avi at avimarcus.net> wrote:
>>>>> > Are multiple 183s from the endpoint that changes the SDP allowed? I'm
>>>>> > under
>>>>> > the impression this is broken, similar to
>>>>> > http://wiki.freeswitch.org/wiki/NDLB#NDLB-allow-nondup-sdp
>>>>> > ... which is why when the codec changes, FS freaks out and cancels
>>>>> > the call
>>>>> > because of codec negotiation error.
>>>>> > Does that NDLB flag allow this, too?
>>>>> >
>>>>> > First has: audio 10116 RTP/AVP 0 101 13
>>>>> > Second has:  audio 49020 RTP/AVP 8 13 101
>>>>> > PCAP: http://ge.tt/7MpyBwJ
>>>>> >
>>>>> > Can someone point me to the specific RFC so I can tell the supplier
>>>>> > to fix
>>>>> > it?
>>>>> > And just curious.. what would make this allowed? A re-INVITE..?
>>>>> >
>>>>> > -Avi
>>>>> >
>>>>> >
>>>>> > _________________________________________________________________________
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>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Kristian Kielhofner
>>>>>
>>>>>
>>>>> _________________________________________________________________________
>>>>> Professional FreeSWITCH Consulting Services:
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>>>>> http://www.freeswitchsolutions.com
>>>>>
>>>>> 
>>>>> 
>>>>>
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>>>>
>>>>
>>>>
>>>>
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>>>>
>>>> 
>>>> 
>>>>
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>>
>>
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>>
>> 
>> 
>>
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>
>
> _________________________________________________________________________
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>
> 
> 
>
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>
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-- 
Kristian Kielhofner