Issue with SRST Fallback with CME and dial peers

Unanswered Question
Apr 10th, 2007

Here is my network setup. Remote site router configured as a MGCP gateway for local calls as well as CME using SRST fallback for emergency services. In normal operations LD calls traverse the WAN and utilize a dedicated T1 pri at a HQ location.

Here is my issue. An analog phone connected to a FXS port will use the local dial peer after a fail over has occured and returned to normal. The issue appears to be the order of the dial peers. Before failover the local pots dial peers were inserted after the MGCP dial peers. In this scenario LD calls placed from the analog set use the MGCP dial peers and LD calls are placed out of a centralized LD pri.

After failover and return to normal state, the order of the dial peers on the router are being reversed. I assume this is because the gateway has registered and the configuration, including the MGCP dial peers, has been pushed to the gateway. If I place a LD call at this point, the calls are routed out the local FXO ports because of pots dial peers that are used during failover.

Is this an issue or operating as designed? Should I be disabling ccm config to prevent this from happening or is there another way to prevent this scenario. Thanks

I have this problem too.
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Erick Bergquist Tue, 04/10/2007 - 13:06

Once MGCP pushes the dial-peers, the first time, they should be there and not created from scratch again. You can remove the ccm-manager config to get around this issue though.

I am confused however, because you mention MGCP, CME, and SRST. IIRC, IOS does not let you configure both call-manager-fallback (SRST) and telephony-services (CME) at the same time on the same router. It's one or the other.

In order to re-order the dial-peers, you'll need to remove them all (including MGCP created ones) and put back your SRST ones from scratch. Then let MGCP create new dial peers after the fact. You may need to do a copy run start (write mem) and reboot though as the old MGCP dial-peer id's may be in memory still and come back at the start of the list instead at the end (after your SRST dial peers).

Another option would be modify your dial-peers, so they handle inbound calls better and terminate on specific dial peers if possible.

crougeau Tue, 04/10/2007 - 13:50

Sorry for the confusion, it is CME with fallback which is all configured under telephony services.

I would agree that after the intial push of the dial-peers they should remain in that order but that is not what is happening. The order of entry is usually what determines their presentation in the router config. We knowingly ordered the local dial peers after the MGCP dial peers to avoid the LD issue but did not anticipate the reorder by mgcp. I was trying to avoid removing the ccm-manager config statements to simplify management for the customer.

brugmanjorge Mon, 06/11/2007 - 10:12

Hi

Would you mind sharing the configuration of your CME router?

I am on my way to deploy the same feature and got to doubts.

1st is whether i should upload the firmwares on the cme router and the 2nd is what happens once the SRST kicks in, will I have problems with incoming/outbounds calls when I fall back to CM Server mode?

Thanks, Jorge

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