Can two unity clusters work with one exchange server

Unanswered Question


Will i need digital networking? I have seen in many posts that digital networking is required for communication between unity clusters. I will have to set up AA on one cluster, so if callers access the AA and dial an extension that is from a different subscriber will the subscriber not get the message if digital networking is not used. I know that the Call Manager will control the send of to extension right?

Why would I need to have digital networking?

Bradford Magnani Fri, 08/13/2010 - 03:40
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Digital networking would be required, yes.  This will allow users to exchange messages between servers.  You can also configure cross-box login and cross-box transfer so that callers can be transferred to subscribers that may not exist on the particular server that was called.

Here is this explained:

Digital networking is pretty straight forward to setup; pretty much definining the Primary Location settings on each failover pair and letting it replicate the GlobalSubscriber information throughout AD.

Hope that helps,


Thanks you have been very helpful.

One last query

The two unity server cluster with failover will be located over a WAN and will have to be routed through a firewall. I have read the networking guide to get the relevant ports to be opened.

From your experience do you see any issues occuring here?

For instance SIte A (Main site)- Unity 1(Active), Unity 2 (Standby), Site B- Unity 1 (Standby), Unity 2 (active).

Will failover work properly, i would like to enable some form of load sharing between sites for the users.

Bradford Magnani Fri, 08/13/2010 - 04:19
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I want to be sure you understand that failover only works between a primary and secondary server in a single pair.  There is no such feature involving a full cluster failover to another cluster (in case that's what you've been referring to the whole time).

If you've got a Unity server at two separate sites separated by a WAN, per the network requirements you're going to need many of the networking infrastructure within the same data center, essentially doubling the resources needed.  Under the "Physical Placement and Network Infrastructure" section in it explains the requirements that may affect your deployment model:

To ensure that Cisco Unity functions properly, we require that a  Cisco Unity server be in the same data center as the following servers:

The  Exchange server that Cisco Unity communicates with, commonly known as  the partner Exchange server. For more information on the partner  Exchange server, see the "Exchange Considerations (All Versions)" section.

Every  Exchange server on which mailboxes for that Cisco Unity server are  homed. If Cisco Unity is separated by a WAN from an Exchange server on  which subscriber mailboxes are homed, a second Cisco Unity server must  be co-located with the remote Exchange server.

At  least one domain controller. If Cisco Unity subscribers are homed in  more than one domain, a DC for each domain must be in the same data  center as the Cisco Unity server.

At least one global catalog server.

At least one DNS server.

As long as the firewall is properly configured to forward the required ports, everything should work successfully.



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