CUCM cluster over the WAN

[rramlal]

Hi Guys,

I have a question for a cluster over the WAN deployment of CUCM. In the event connection is lost between the Pub and Sub but the connections between the cluster and the phones are up, what occurs?

Would the pub remain up and the secondary go down? what would happen in a case like this where the cluster would be down, but still be accessible to the branch sites?

[Terry Cheema]

Unless the phones lose keepalives to the primary server, they will usually stay registered to their primary server.

It will largely be a split brain scenario both sides will keep on working. But there will be some problems like:

• Phones registered to one server may not be able to call the phones on other server due to a break in Intra cluster signalling.
• Active Calls may also be dropped depending upon where the gateways/Route lists are registered to.
• For Contact Centre, Agents may get kicked out of CAD
• The database replication will be broken - which apart from other bad things, will not push changes from Pub to other servers. So if you reboot a phone or make any change to a phone registered on a subscriber that publisher has lost connection to - the changes will not be honored.
• RTMT will throw out couple of alarms - main one to look out for this one will be SDLLinkOOS - telling the SDL link is out of service.
• It may also generate alarm the number of registered devices has significantly dropped (due to the fact you are logged on to Publisher RTMT and its no longer able to see those devices).

-Terry

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