SBC Doesn't Forward ACK (Doc ID 2244257.1)

Last updated on MAY 23, 2017

Applies to:

Acme Packet 3820 - Version E-Cz7.3.0 to E-Cz7.3.0 [Release E-Cz7.0]
Information in this document applies to any platform.

Symptoms

 It has been observed that  SBC sometimes not forwarding the ACK which is sent for  200OK. We see in a trace that the SBC gets the ACK from UserA, the SBC forwards it to the SIP Server, the SIP Server returns the ACK to the SBC and now the SBC is supposed to send the ACK to UserB but it doesn't send it.

 

USER-A              SBC            SIP-SERVER          USER-B

----INVITE------->
                          ------INVITE----->
                           <-----INVITE-----

                            ---------------INVITE------------->

                         <--------------180 RINGING----------
                          --------180 RINGING->
<---------180 RINGING-
                           <--------------200Ok---------------
                         --------200OK->
                         <---------200OK-

<------200OK------
-------ACK------->
                        ------ACK------->
                        <----ACK---------
                         -------ACK(DROPPED)--------------->
( THIS ACK was dropped by SBC DUE to duplicate branch i.d)

 

Cause

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