This document outlines the automatic creation of dial-peer when using the ccm-manager command and how it affects router operation when we also have SRST dial-peers on the router and someone reconfigures the port.
When the MGCP controlled Analog ports are configured on the Call Manager and we put the ccm-manager config and ccm-manager config server command on the gateway, the dial-peers are downloaded automatically from the call manager. The dial-peers for the SRST can then be configured afterwards. We see that if we delete the port and add the port again and appply the configuration the dial-peer moves to the bottom of the configuration. i.e. below the SRST dial-peers. This causes the calls to start failing or go via SRST dial-peer as that is above the MGCP dial-peer in the router’s config.
Here are some outputs from my lab router. The system image file is "flash0:c3900-universalk9-mz.SPA.152-3.T2.bin" and I am using call manager version 8.0.3.10000-8. After adding the voice port (MGCP controlled) this is what I see on the show dial-peer voice sum. Last two dial-peers are what we are concerned about…
After this I create the dial-peer for SRST, Now I delete the port on the call manager and then add it again. When the port gets deleted the dial-peer is removed and when the dial-peer is added again
So when in practical environments, if someone deletes the port on the call manager and also bounces the MGCP stack on the gateway or removes the ccm-manager config command, the dial-peer which gets created automatically gets deleted.
Also when we add the port again, we see the new dial-peer at the bottom of the config, which is by design.
To get around this problem you can do the following:
- •1. Add “service mgcpapp” on the SRST dial-peers to have the calls routed via the default application in the event when the call manager is not available. So adding the service mgcpapp command on the dial-peer will mean that the gateway will route the calls via MGCP when it’s available even if it hits the SRST dial-peer (which is hit because its above the MGCP dial-peer as we deleted and re-added the port), but if it’s not available it will use the default application.
- •2. We can remove the ccm-manager config command from the router after are done with all the configuration. Removing the command will ensure that the new config is not downloaded all the time and thus the dial-peer will remain intact.
I must point out that this is by design and is expected behavior. The above two pointers are workarounds if one is consistently, deleting and re-adding the ports on the call manager. Ideally once the deployment is done, we should not de deleting and reading the ports on the call manager frequently.