[SR-Users] Same Via Tag for INVITE and ACK on S/L loadbalancer

[Daniel-Constantin Mierla]

In such case, because the proxy is doing stateless forwarding, there is
no transaction. I guess the solution right now is to use tm for relaying
- is any concern of doing that?

If someone wants to look at generating same via branch, I am fine with
it, eventually controlled by a parameter if the code change is
significant, to be able to switch to current mode if unexpected side
effects pop up.

One more note in this case: I expect it would be required to generate
different tag for 200ok ACK, so it is matched as different transaction
by next hop, not sure if there is any easy way to discover the type of
ACK in a stateless proxy.

I am not sure I remember correctly, but in some discussions I think it
was suggested to just reuse the branch value of incoming top Via when
doing stateless forwarding.

Cheers,
Daniel

On 10.02.20 16:26, Sebastian Damm wrote:
> We use 5.2 on the affected systems.
>
> On Mon, Feb 10, 2020 at 4:15 PM Serge S. Yuriev <me at nevian.org> wrote:
>> Hi
>>
>> I believe you are using 5.2 or 5.3 series? This tend to work properly on 5.1 series
>>
>> 10.02.2020, 18:10, "Sebastian Damm" <damm at sipgate.de>:
>>> Hi,
>>>
>>> actually, our only problem is handling negative replies. The ACK
>>> belongs to the same transaction and therefore has to carry the same
>>> Via branch ID.
>>>
>>> Sebastian
>>>
>>> On Mon, Feb 10, 2020 at 3:50 PM Yuriy Gorlichenko <ovoshlook at gmail.com> wrote:
>>>>  ACK for successull response is a new transaction. It has to be different. May be it is better to point provider to this?
>>>>
>>>>  On Mon, 10 Feb 2020, 14:26 Sebastian Damm, <damm at sipgate.de> wrote:
>>>>>  Hi,
>>>>>
>>>>>  I stumbled upon an interop problem with a carrier. We have the
>>>>>  following scenario:
>>>>>
>>>>>  Gateway --> Loadbalancer --> Carrier
>>>>>
>>>>>  The loadbalancer generates a Via header for each request. But since it
>>>>>  is stateless, the Via tag is generated for each request. As a
>>>>>  consequence, the Via tag in the ACK differs from the one in the
>>>>>  INVITE. And one carrier doesn't handle those ACKs if the Via tag
>>>>>  differs.
>>>>>
>>>>>  Is there a way to force the creation of a "deterministic" Via branch
>>>>>  tag? For example, building it from a hash over call-id and from-tag or
>>>>>  something like that?
>>>>>
>>>>>  Thanks in advance
>>>>>  Sebastian
>>>>>
>>>>>  --
>>>>>  Sebastian Damm
>>>>>  Voice Engineer
>>>>>  __________________________________________
>>>>>  sipgate GmbH
>>>>>
>>>>>  _______________________________________________
>>>>>  Kamailio (SER) - Users Mailing List
>>>>>  sr-users at lists.kamailio.org
>>>>>  https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
>>>>  _______________________________________________
>>>>  Kamailio (SER) - Users Mailing List
>>>>  sr-users at lists.kamailio.org
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>>> --
>>> Sebastian Damm
>>> Voice Engineer
>>> __________________________________________
>>> sipgate GmbH
>>>
>>> _______________________________________________
>>> Kamailio (SER) - Users Mailing List
>>> sr-users at lists.kamailio.org
>>> https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
>> --
>> wbr,
>> Serge
>>
>>
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>
-- 
Daniel-Constantin Mierla -- www.asipto.com
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