Clustering Call Managers across the WAN

[mgvogt11]

We are going to add a new site (Location2) into our current design. It will be just as big as our current central location. The question I have is the following.

scenario 1:

If I create a new publisher and subcriber at (Location2) how do I tie it into the current Location 1 which also has a publisher and subscriber. Can I use a Non-Gatekeeper Inter-Cluster Trunk to connect both locations? Can there be two Publishers?

scenario 2;

If I create two subscribers (local failover) at (Location2) can I create an Non-Gatekeeper Inter-Cluster Trunk to connect both locations or are they completely seperate? Can you ever promote a subscriber to become a publisher?

[carijit]

Hi,

Scenario1

Yes you can create a separate Call Manager Cluster for you second site whcih can intercat with your other cluster through Inter Cluster trunk(which can be either gatekeeper controlled or non gatekeeper controlled depending your requirement for CAC).

You cant have two Publishers in a cluster.

Scenario 2

You can have subcriber(s) in your second site as a extension to your existing cluster but for that the round trip delay between your PUB and the remote sub should be less than 40ms. Thats a requirement, else you gonna have some replication and related issues.

Also you have take extra care in regards to QoS for the WAN link between the remote SUB and the PUB.

Hope this helps.

Thanks,

Arijit

[mderriennic]

You'll find all deployments models along with benefits & requirements in the CCM4 SRND :

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_implementation_design_guide_chapter09186a00802c37c8.html

[mgvogt11]

So the rule of thumb is that no matter how many clusters you can only have 1 publisher?

If there are 3 locations hong kong, london, miami and we want to connect all three. There can only be one publisher?

[carijit]

Yes.

If you have sites in HK, London and Miami you end up with 3 different clusters cause of the 40ms RTD restriction.

[mderriennic]

You must have one and only one publisher per cluster.

If you met Cisco pre requisite you can set up a cluster over the wan with one publisher and several subscribers in your different locations.

If not (probably your case with these locations), you have to set up multiple clusters with trunk between them.

Marc

[mgvogt11]

Location 1: HK

Publisher

Subscriber

Location 2:London (Main 4-Call Centers)

Publisher

Subscriber

IPCC 3.5

Unity 4.0

Location 3:Miami

Publisher

Subscriber

All locations can be connected to each other via Intercluster Trunk? 4 digit dialing should work to all locations?

Can Unity 4.0 and IPCC 3.5 be located at a central location if total round trip is less than 40ms in the scenario above? I understand the pro's and con's I just want know if this is supported?

The overall question is: Can you have 2-3 clusters across the WAN and run IPCC3.5 and Unity 4.0 from one of these locations? The scenario in real will have 10MB pipe between all locations.

[carijit]

All 3 locations can be connected through ICT(Inter Cluster Trunk) preserving 4 or 5 digit dialplan(no overlapping). Its better to have a access code for the Intercluster trunk calls to allow extension overlapping for locations.

As per you scenario here, the Unity VM can be configured to support the 3 clusters which means you can have the Unity located centrally and your remote clusters getting service from the central Unity Server.

As per as your IPCC Express is concerned it cannot be shared across the clusters. You need to have dedicated IPCC Express servers for every Call Manager Cluster.

[mderriennic]

More informations about Unity and multiple CallManager Cluster :

Cisco Unity Integration with Multiple Clusters of Cisco CallManager 3.1 and Later (All Versions of Cisco Unity)

http://www.cisco.com/en/US/partner/products/sw/voicesw/ps2237/products_white_paper09186a00800872c8.shtml

And you're right, no solution for IPCC Express because you have to configure Directory integration and JTAPI connexion with a CCM Cluster but there is no possibility to configure multiple instances.