[Users] ACK is sent before the re-INVITE to OpenSER, but the proxy relays the re-INVITE first (call flow in the body).

Bogdan-Andrei Iancu bogdan at voice-system.ro
Tue May 9 18:46:27 CEST 2006


Hi Alexandre,

if I'm not wrong ,this topic was previously discussed on the mailing 
list. The idea is that openser cannot guarantee that messages will be 
sent in same order as received. And this because of parallel 
multi-process execution.

the idea is that the CC1 shouldn;t send a re-INVITE so fast and also the 
GW should wait a little bit to see if ACK is delayed or not.

if you are running in full debug, the logs will might help you to see 
how the ACK and INVITE gets swapped during processing.

regards,
bogdan

Alexandre Abreu wrote:

>Hello.  
>
>Below it's the call flow.
>
>
>    UAC          CALL CONTROL 1      OPENSER 1      	  GW
>     |                |                |                |
>     |   INVITE F1    |                |                |
>     |--------------->|                |                |
>     |     100  F2    |                |                |
>     |<---------------|   INVITE F3    |                |
>     |                |--------------->|                |
>     |                |     100  F4    |                |
>     |                |<---------------|     INVITE F5  |
>     |                |                |--------------->|
>     |                |                |     183 F6     |
>     |                |     183 F7     |<---------------|
>     |     183 F8     |<---------------|                |
>     |<---------------|                |                |
>     |                |  Early Media   |                |
>     |<==============>|<===============|================|
>     |                |                |      200 F9    |
>     |                |    200 F10     |<---------------|
>     |                |<---------------|                |
>     |                |                |                |
>     |                |     ACK F13    |                |
>     |                |--------------->|                |
>     |                |  re-INVITE F14 |			   |
>     |                |--------------->|                |
>     |                |                | re-INVITE F15  |
>     |                |                |--------------->|                
>     |                |                |   ACK  F16     |
>     |	          |                |--------------->| 
>     |                |                |                |
>     |                |                |    500 F17     |
>     |                |                | <--------------|
>     |                |                |                |
>
>
>The problem is between F13 and F16. Why OPENSER relays the re-INVITE first
>(F15), if the ACK (F13) was sent before and arrives before?
>And I am sure that this ACK hits a t_relay(), because after the re-INVITE
>sent, the ACK (F16) is sent normally...
>
>I am using OpenSER 1.0.1.
>
>Any help is appreciated.
>
>Alexandre
>
>
>
>
>
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