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how to configure ILS between 2 CUCM clusters

Hi All

I need to configure ILS between 2 different CUCM clusters to enable our MRA clients to work correctly.

I don't want to use TLS and keep it as simple as possible.

What are the basic steps? 

Does it require any downtime?

Do you need to restart any critical services after?

can you do it in live without taking anything down?


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VIP Collaborator

Re: how to configure ILS between 2 CUCM clusters

Setting up ILS is pretty easy. Are you using this for home cluster information, global dialplan replication, or something else? Depending on the use, there are a couple of different prep steps that are recommended.

If you don't want to use TLS, you can set the two systems up with a password instead. Just be sure to uncheck the TLS checkbox.

IF your clusters already have unique Cluster IDs (very first Enterprise Parameter), then configuring ILS does not require any downtime, can be done during the production day without hurting anything (although I'd still do it off hours because I'm a safety kind of person), and no services need to be restarted after implementation.

IF your clusters do not yet have unique Cluster IDs, then those need to be changed first. The system will tell you that all services need to be restarted after this change and restarting your clusters is probably the easiest way to do that. In my experience, if ILS is the only intercluster thing you are doing then the services restart is not immediately necessary.

Here is a link to setting up ILS. If you are also doing GDPR, you will want to set those components first:

System Configuration Guide for CUCM 12.0(1) - Chapter: Configure ILS



Re: how to configure ILS between 2 CUCM clusters

Hi there

it is for jabber, we have 2 clusters, however we have expressways in those sites, when the users come in, they always get pushed to the same CUCM due to uds lookup, so it hits our CUCM and authentication fails as it cannot find the user.

would ILS fix this ?

VIP Collaborator

Re: how to configure ILS between 2 CUCM clusters


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