One way audio after moving serial interface

Unanswered Question
Jul 16th, 2008

We have a new voice design in the testing phase, where the traffic path was shown below. This setup was working:

Verizon-->Edge_Router-->IP2IP Gateway-->Call Manager

The IP2IP Gateway router was sitting with a single ethernet interface on the core switch.

The SIP trunk is physically connected to a serial interface on the Edge router and Verizon was sending their Sip invites to the IP2IP Gateway etherent interface, where the h323 binding is. The calls were working this way inbound and outbound.

The system is designed to dynamically fail over to our DR site if we loose the trunk to Verizon in the main site.

Verizon will route the calls to our DR Trunk and IP2IP Gateway router.

We found with this scenario that the IP2IP gateway router could not detect when the serial interface on the edge router went down and therefore Call Manager would not route calls to the DR Side.

The Voice Engineer had us change the existing config by moving the serial interface to the IP2IP Gateway router:

Verizon-->IP2IP Gateway-->Call Manger

Since we made that move (nothing else has changed) we have had one way audio and cannot find the problem.

The Voice Engineer is stuck and has opened a TAC case and we do not seem to be getting anywhere with that either.

Does anyone have any input on any of this?

Any input would be appreciated.

I have this problem too.
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wilson_1234_2 Thu, 07/17/2008 - 04:08

In case anyone is interested, my serial interface had this line in the config:

ip verify unicast reverse-path

I removed this line and that corrected the problem.

tim.giles Thu, 07/17/2008 - 04:21

Do you have a SIP trunk configured on the CallManager to allocated an MTP to the calls?

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