Information Technology Reference
In-Depth Information
own cluster, CUCM can also connect to voice gateways (such as a Cisco router),
which can connect to various other voice networks (such as the PSTN or legacy PBX
systems).
Built-in Disaster Recovery System (DRS):
As a built-in feature, the CUCM DRS
service allows you to back up the CUCM database (and any additional files you'd pre-
fer) to a network device or over Secure FTP (SFTP).
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VMWare Virtualization Support:
If you love VMWare, you'll love the fact that
CUCM 8.0 is supported in a VMWare ESXi environment. This brings all the high
availability and scalability benefits of virtualization to your CUCM deployment.
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Directory service support or integration:
VoIP networks can use network user
accounts for a variety of purposes (phone control, attendant console control, and so
on). CUCM has the capability to be its own directory server to hold user accounts or
it can integrate into an existing corporate directory structure (such as Microsoft Ac-
tive Directory) and pull user account information from there.
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Note:
Cisco does produce a single-server CUCM solution known as CUCM Business
Edition. This single server provides CUCM, Unified Mobility, and Unity Connection for up
to 500 IP Phones at an aggressive price. The catch? CUCM Business Edition does not sup-
port clustering (server redundancy).
CUCM Database Replication and Interacting with Cisco IP Phones
Even though CUCM can scale to a massive size, it interacts with Cisco IP Phones in a simi-
lar manner to CME...just bigger! The first thing you'll want to catch is that CUCM works
in a cluster relationship. When most people think of a server cluster, they think of multi-
ple servers with mirrored configurations that assume the identity of each other in the case
of failure. That is
not
the functionality of a CUCM server cluster. Instead, think of a
CUCM server cluster as multiple, individual servers with their own, unique configuration
working for the common good of the IP Phones. The CUCM cluster relationship includes
two types of communication:
CUCM Database Relationship:
The CUCM IBM Informix database includes all the
“static” data of the cluster (directory numbers, route plan, calling permissions, and so
on). This data replicates to all the servers in the cluster.
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CUCM Runtime Data:
Just like the name sounds, the runtime data encompasses
anything that happens in “real time” in the CUCM cluster. For example, when a de-
vice registers with a CUCM server, it communicates to all the other servers that it
now “owns” that IP phone. CUCM uses a method designed specifically by Cisco for
this type of communication: Intracluster Communication Signaling (ICCS).
Although the CUCM runtime data is important for functionality, there's simply not too
much to it. All the servers in the CUCM cluster form TCP sessions to each other for ICCS
communication (TCP ports 8002 to 8004). Then, anytime something of interest happens
(such as a phone registering, a call initiation, a call disconnect, and so on), the servers in-
form each other of the event. All this ICCS communication takes virtually no additional
configuration on your part (other than adding the CUCM server to the cluster).
