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AMA-CUCM Troubleshooting: Best Practices for Reading Trace Files

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Re: It will work the same way as

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.


Re: It will work the same way as

Thanks Slavik - so ILS is just being used to identify where is the user's home cluster?
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Re: It will work the same way as

Yes, for authentication purpose, yes. ILS has more features like learning routing from other clusters and etc. But in our case, ILS also learns where each user is located.

Re: It will work the same way as

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


Hi Jaime

Hi Jaime

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 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

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The answer remains the same,

The answer remains the same, the external SRV record has nothing to do with the ILS config that is required internally.



if this helps, please rate

Re: Assuming you have a proper

Hi Jamie,

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,

Everyone's tags (1)
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Re: Assuming you have a proper

You cannot configure the same user with "Home Cluster" in few clusters, because he won't be able to login anymore. The Home Cluster just states which cluster is managing this user, and again, you cannot have a few "homes" (heh) for a user.
When you set the Home Cluster to a user, and the login request is forwarded to a cluster that this user isn't located at (the "Home Cluster" not checked, I mean), via ILS this cluster knows that this user is located at some other cluster, and will forward the client to login to the correct cluster.

Re: Assuming you have a proper

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.

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Re: Assuming you have a proper

I'm not sure about the last part. But generally, you'll have to manage your users wisely, meaning you'll have to go one by one and check (or un-check) the "Home Cluster", so that each user will have only one home cluster. I have a customer with 3 clusters, and we're managing users in all 3 of them, that each user is in his own home cluster, otherwise it won't work. And, change your feature group in both clusters, and change the "Home Cluster" so it WONT BE CHECKED when a new end user is synced, because from now on you'll have to manage it manually.
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