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[BLOG #3] EMCC & Directory Sync
EMCC and Directory Synchronization: Be careful what you sync!
Tags: Frink  CISCO  Tech Factors  collaboration  advanced services  EMCC  VOIP  PBX  CUCM 
One attractive new feature of UCM 8.x is Extension Mobility Cross Cluster (EMCC).
Extension mobility is the term used by Cisco for the ability to use a device profile to log into a EM capable phone, therefore preserving your personal settings (speed dials, your number etc.) while being on a different desk. This feature is often used for shared desks or guest offices.

One of the caveats of EM was that one could only log into devices on a single cluster, e.g. if the organization has multiple clusters, user device profiles could not be used between clusters.

This limitation has been resolved in UCM 8.x with EMCC. EMCC allows one cluster to dynamically query "linked/trusted" clusters for a device profile. The CCM Features Guide has a very nice diagram showing the login process.
One point needs to be emphasized

For this to work, userIDs have to be unique across cluster and must not be duplicated. So if I am User "balbler" and the cluster in SJ is my home cluster and i want to do a EMCC login on the AMS cluster, my userID MUST not exist on the AMS cluster.
The reason for this is quite simple: The EMCC process will only query the remote cluster if it cannot find the user in the local CCM db.

This is quite easy to do if you have a local user db. It gets slightly more complicated if you bring LDAP integration into the picture. DirSync allows you to sync userIDs from a LDAP directory (e.g. Active Directory or OpenLDAP) into the UCM user DB.
Most customers will have a single, global LDAP directory for the whole organization .
In that case for EMCC to work, you have to make sure that usernames are not duplicated because of the sync.

There are 2 options on fulfilling this requirement:

• If possible sync only a part of the LDAP tree (a subtree)
• Filter based on an attribute: This can be done via GUI on UCM 8.x (and was possible via sql manipulation of the ldapconfig table in prior versions)

So when planning on using EMCC and are already using LDAP Synchronisation, one needs to make sure there is a way to properly filter the users so there is no userID duplication.

Be aware that this will also mean that the CCM generated corporate directory will only contain the users from the local cluster. For a complete directory the CorpDir XML service will have to be replaced.
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Editorial Team: Bernhard Albler