We have two CCMs in a cluster and running extension mobility on one of the server, if that particular server goes down we are unable to login on phones. Can we have redundency on extension mobility service in the cluster?
I would request you to refer to SRND to answer this question:
As per the recomendation mentioned in the srnd document i have created another service on subcriber (already configured service was on publisher), now phones subcribed to this 2nd service show both services. When we press "services" button on the phone, phone shows both services and we can login using any of these two services but the issue is when we bring publisher down none of the service becomes available on phones for login. When the publisher is down and we press the 'services' button on phone we get message ' host not found'.
It's a two stage thing - the services list is retrieved from the services URL, and that provides your list of subscribed services.
You need to go into Enterprise Parameters, and make the Services and Secure Services (and the directories, authentication and other standard and secure URLs) redundant as well. Most customers don't have load balancers so I've been using round-robin DNS to do this; it's not perfect as not all phones deal well with the round robin, but it's better than nothing.
You can use a software solution for this called ALM. (use google)
This piece of software autmaotically logs in a user with windows.
And, the best of all, it support CUCM redundancy.