From what I remember when I investigated this exact question, it looks for the user's home cluster with using simple REST request towards the CUCM (with TCP/8443). It'll ask for a 'Cisco-UDS' and the CUCM will return a XML response that will contain some details about the user, and he's home cluster. Once the Expressway-C gets the user's home cluster, it knows when to forward the next relevant messages, which is also with TCP/8443 but in the end, if you're using phone services (and I bet you do) it'll end with trying to send a SIP REGISTER towards CUCM.
It'll be better if you use the port usage guide of Expressway, so you won't miss anything.
Hi Jaime & Everyone,
Sorry to bump an old thread, but I'm looking for something else and seeing a lot of misinformation.
The cisco documentation states that ILS is required to find a users home cluster in a multi cluster deployment. This is not the case.
Finding the users home cluster is solely performed by the UDS service. I have argued this point many times with Cisco TAC during troubleshooting multi cluster deployments. You can test it yourself. In the example below, I pointed the HTTPS Query at a server that the user is NOT marked as the home cluster on. It is a cluster of 3 separate call mangers with UDS Configured, but ILS is NOT Configured.
You'll get something like:
<clusterUser version="10.5.2" uri="https://CUCMIP:8443/cucm-uds/clusterUser?username=USERNAME">
<result found="true" uri="https://HOMECLUSTERHOSTNAME:8443/cucm-uds/user/USERID" version="10.5.2"/><homeCluster serversUri="https://HOMECLUSTERHOSTNAME:8443/cucm-uds/servers">HOMECLUSTERHOSTNAME</homeCluster><homeClusterDetails><selfProvisioningSecureMode>true</selfProvisioningSecureMode><adminProvisionMode>false</adminProvisionMode></homeClusterDetails></clusterUser>
Notice its returned a different cluster for home cluster to the one I pointed the request at.
Cisco have also logged a bug to adjust the documentation
ILS Is only used as part of global dial plan replication. It is not required for anything other than that.
For further information on UDS, see here
Forgot to mention in my previous reply that the collab edge srv records are created in both USA and EU DNS which are replicated within the same abc.com domain so that EU users will be pointed to EU expressway edge and USA users will be pointed to expressway edge in USA. Now the issue is when the user travel from one region to another and vice versa
The answer remains the same, the external SRV record has nothing to do with the ILS config that is required internally.
We have a multi-cluster environment with ILS configuration working properly. I can verify that as other regions show in Learned Directory URIs. My question to you is that many of the users are Home Clustered to more than 1 cluster in End-User. Is that going to be a problem for Jabber logins etc? Also, what is the importance of Home Cluster?
Thank you Slavik.
Unfortunately, Cisco defaulted all users to be homed through feature group template. Maybe there is a process to fix this but the only way I know is to get this done manually. Every time we home a user to where they belong and unhome from irrespective clusters. User still defaults back to the original cluster they were homed on which throws me off as they are not checked there anymore as home cluster. Not sure if this is a bug with 11.5.1.