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Community Member

cisco call manager pub & sub definitions

I'm just beginning to learn Cisco VOIP. Can someone explain to me in a simple way what SUB & PUB mean in relation to Cisco Unity & call manager mean, and how it's used in the real world. My supervisor wants me to do a unity & UCM backup, and I'm not really sure what I'm doing

Thank You very much.

Cisco Employee

Unified CM Cluster

Unified CM Cluster Services

Basically, the PUB holds the DB in all clusters, it may, or may not run CUCM services (depends of size)

SUBs always run the CUCM service, they depend on PUB for changes to the DB, aside from UFF.



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Community Member

I really appreciate the

I really appreciate the response, but I don't have the slightest idea what your talking about. I'm a total novice in this area. If possible could you restate the response in a way I might be able to understand it. If you can't, I understand.  I will look at the document. Thank You very much.

PUB = PublisherSUB =

PUB = Publisher

SUB = Subscriber.

In simple terms, think of the Publisher as the manager of the CUCM cluster. Configuration changes are typically done on the Publisher, and it distributes those changes to the Subscribers. Subscribers perform call processing, phone registration, software conference bridge, music on hold, etc., and in some setups the Publisher will as well (depends on size and design, as Jaime mentioned).

The Pub-Sub relation for Unity is a little different... which one handles voicemail traffic depends completely on how the connectivity with CUCM is configured. In some setups, they will be distributed voicemail traffic evenly, while in other setups the Pub may get all traffic until its ports are full, and then overflow to the Sub as a backup.

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