MGCP Redundancy within CCM Cluster

Answered Question
Aug 15th, 2007
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I have a three server cluster, with multiple remote sites. My concern is that if the pub fails, that the gateways will not register to the fallback servers. Is the "CCM-Redundant Host" command sufficient for this?


Thanks

Correct Answer by Rob Huffman about 9 years 10 months ago

Hi Robert,


Here is a doc that outlines the required steps;


Cisco IOS gateways can maintain links to up to two backup Cisco Unified CallManager servers in addition to a primary Cisco Unified CallManager. This redundancy enables a voice gateway to switchover to a backup if the gateway loses communication with the primary. The backup server takes control of the devices that are registered with the primary Cisco Unified CallManager. The second backup takes control of the registered devices if both the primary and first backup Cisco Unified CallManager fail. The gateway preserves existing connections during a switchover to a backup Cisco Unified CallManager.


When the primary Cisco Unified CallManager server becomes available again, control reverts to that server. Reverting to the primary server can occur immediately, after a configurable amount of time, or only when all connected sessions are released.


Switchback


Switchback is the process a voice gateway uses to reestablish communication with the primary Cisco Unified CallManager server when the server becomes available again. Switchback can occur immediately, at a specified time after the last active call ends, or after a specified length of time.


MGCP Gateway Fallback


The MGCP gateway maintains a remote connection to a centralized Cisco Unified CallManager cluster by sending MGCP keepalive messages to the Cisco Unified CallManager server at 15-second intervals. If the active Cisco Unified CallManager server fails to acknowledge receipt of the keepalive message within 30 seconds, the gateway attempts to switch over to the next available Cisco Unified CallManager server.




SUMMARY STEPS


1. enable


2. configure terminal


3. ccm-manager redundant-host {ip-address | DNS-name} {ip-address | DNS-name}


4. ccm-manager switchback {graceful | immediate | schedule-time hh:mm | uptime-delay minutes}


5. ccm-manager fallback-mgcp


6. call application alternate


7. exit


8. ccm-manager switchover-to-backup



From this good doc;


http://www.cisco.com/en/US/products/ps6441/products_configuration_guide_chapter09186a00805583bd.html#wp1056830


Hope this helps!

Rob

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Correct Answer
Rob Huffman Wed, 08/15/2007 - 05:34
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Hi Robert,


Here is a doc that outlines the required steps;


Cisco IOS gateways can maintain links to up to two backup Cisco Unified CallManager servers in addition to a primary Cisco Unified CallManager. This redundancy enables a voice gateway to switchover to a backup if the gateway loses communication with the primary. The backup server takes control of the devices that are registered with the primary Cisco Unified CallManager. The second backup takes control of the registered devices if both the primary and first backup Cisco Unified CallManager fail. The gateway preserves existing connections during a switchover to a backup Cisco Unified CallManager.


When the primary Cisco Unified CallManager server becomes available again, control reverts to that server. Reverting to the primary server can occur immediately, after a configurable amount of time, or only when all connected sessions are released.


Switchback


Switchback is the process a voice gateway uses to reestablish communication with the primary Cisco Unified CallManager server when the server becomes available again. Switchback can occur immediately, at a specified time after the last active call ends, or after a specified length of time.


MGCP Gateway Fallback


The MGCP gateway maintains a remote connection to a centralized Cisco Unified CallManager cluster by sending MGCP keepalive messages to the Cisco Unified CallManager server at 15-second intervals. If the active Cisco Unified CallManager server fails to acknowledge receipt of the keepalive message within 30 seconds, the gateway attempts to switch over to the next available Cisco Unified CallManager server.




SUMMARY STEPS


1. enable


2. configure terminal


3. ccm-manager redundant-host {ip-address | DNS-name} {ip-address | DNS-name}


4. ccm-manager switchback {graceful | immediate | schedule-time hh:mm | uptime-delay minutes}


5. ccm-manager fallback-mgcp


6. call application alternate


7. exit


8. ccm-manager switchover-to-backup



From this good doc;


http://www.cisco.com/en/US/products/ps6441/products_configuration_guide_chapter09186a00805583bd.html#wp1056830


Hope this helps!

Rob

Tommer Catlin Mon, 08/27/2007 - 15:59
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Hey Rob!


I have a super weird problem. I just put in a 5.1 cluster pub and sub. Works great, but when I put in the CCM-manager config mode, MGCP goes in and changes the ccm-manager redundant host from IP to hostname of the PUB.


Then, my PRIs drop out of the registration, the house starts to fall apart. What gives? Are routers and CCM 5.1 using DNS only now?? I know that the CCM uses it, but the routers for MGCP??


I have never seen this before. Or do I need add some kind of DNS entry into the router so it can resolve the hostname of the CCM pub and sub? Kind of hate to do that and have the router rely upon DNS also.


Thanks and take care!

mchandak Mon, 08/27/2007 - 16:09
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One reason why this could be happening is that the Servers entered in the CM list is hostname and not IP Address. To work around this you would either need a DNS Server or on the CallManager Admin Page, go to System | Servers and change the Hostname to IP Address. Once this is done, you would need to reset the devices for it to download the re-generated configuration and re-register to the CM.


Please note that this change would be cluster wide and not only for the MGCP Gateways. So you should reset all the devices in the cluster once this is done.


Hope this helps

Tommer Catlin Mon, 08/27/2007 - 16:11
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Ahhh.. that does make sense. Sorry for my IOS skills on the gateway, but cant I add a DNS server entry so the gateway can resolve the hostnames of the CCM?


Or what is best practice? Change the system|servers and change them to IP?


Thanks!



mchandak Mon, 08/27/2007 - 16:14
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It is always recommended to use IP Address and not hostname. This is to aviod any kind of DNS issues.

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