Communication Manager 8.x: Cross Cluster Extension Mobility lab attempt - part 1

EMCC lab attempt notes

As one of the new features in CUCM 8.x, it seems like a good candidate to lab.

This will not be the first time this topic is mentioned on the Cisco subnet, readers are encouraged to look at Dennis Hartmann's post on the subject, still I think it's going to be beneficial to others if I share my lab notes.

To get going I got a hold of the latest Features and Services guide and started to read. It starts on page 269 and continue until page 324 (that's 55 pages).

So far from my initial reading, it seems like the way intercluster extension mobility (EMCC) works is as follows:

  1. A non local user is getting into the services portion of the phone, select the extension mobility and authenticate.
  2. The phones cluster (visiting cluster) attempts to authenticate the user and does not find a device profile for the user. It then tries to contact a configured list of remote clusters and authenticate the user with them.
  3. Once the user's home cluster authenticates the user, the TFTP is switched to the home cluster and a device profile is downloaded and merged with the phone's configuration.

This means that the remote phone (in the visiting cluster) will register with the user's home cluster since the device profile resides there. This creates challenges with PSTN related scenarios since the visiting user's local and emergency calls should be routed via the visiting cluster and not the home cluster (which the phone is registered with). The way this is handled is by using an intercluster SIP trunk and intercepting the calls so that they will route via the local cluster.

Here is a Cisco generated drawing for a 911 call scenario:

It is taken from the following URL:

I can't lab all this but will definitely try to get the basics/software only features of it tested.

First thing is to install two CUCM servers on VMWARE and hopefully get them both to work on my laptop at once, when this is done I'll follow the configuration steps and share my notes from it, hopefully it will assist others when they try to do the same.

To be continued, Avner.

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