Incoming Calls not processed by CUCM Sub when PUB is Down

[Patrick Sharp]

We have 3 node CUCM cluster with a PUB and SUB at HQ and a SUB at the DR site. We also have CUBE setup with SIP to the PSTN on a router at HQ and a router at DR. When  I shut down the PUB, calls are not being processed by any of the two SUBs (The SUB at HQ or the SUB at DR). Where in the router config or CUCM should I look to configure so the SUBS can process calls when PUB is down.

The SIP to PSTN failover does work on the Telco Provider end.

[TechLvr]

Make sure your CUCM facing dial peer uses a server group with a list of all three of your CM nodes. 

Or you could use three dial peers facing CUCM. Each dial peel will point to one of your CM nodes. You can the use the “preference 1” under the first dial peer, “preference 2” under the second dial peer and “preference 3” under the third one. 

[Roger Kallberg]

Apart from the advice given by @TechLvr make sure that you have Run on all nodes checked on the SIP trunk in CM and on the route list. Also a non related advise that has to do with outbound calls, if your using the recommended way for matching inbound dial peer with information in the VIA header you’ll need to make sure that all three CMs are in the voice class used for this.

For additional information on your question and my additional advice please see this outstanding document that should be in the link list of any engineer in the UC field. In Depth Explanation of Cisco IOS and IOS-XE Call Routing It is the holy grail of documents.

[Nithin Eluvathingal]

There are multiple things you must check.

- Check if you have enabled "Run on all Node" as @Roger Kallberg mentioned on your CUCM trunk/gateway configuration page.

If not enabled enable,and restart the gateway/Trunk.

There should be Dial-peer toward all CUCM nodes from the gateway as @TechLvr

2.12.0.0