Locations feature in callmanager

[arvind.krishna]

I have 750 odd locations connected via an IP backbone in a hub and spoke topology, all these locations will use 3-4 IP phones each. How do i handle it?

1. callmanager cluster at the central location for centralised call processing, i believe only 500 locations can be configured per callmanager?

Will i need another callmanager cluster?

Do i require a gatekeeper?

What is the suggested callmanager model?

[sdjono]

For centralized processing You can group locations with the same bandwidth together. For example you have 150 locations with 64kbps, 100 locations with 128kbps, and 200 locations with 256kbps. You only need to configure 3 locations and then assign it to the respective sites.

[pbarman]

But the only problem with this is if two sites assigned to the same location call among themselves, the call will be considered within location, and Callmanager will not block the call. Now the bandwidth will be oversubscribed on your WAN and the voice quality would degrade, and the sole purpose of location would be undermined.

I would suggest that you add another CCM cluster, and add 400 and 350 locations to each cluster respectively. Do a intercluster trunk between the two CCM clusters.

Also if your remote sites will have 3 or 4 phones, you can very well use Callmanager Express at some sites.

For the sites that belong to the same CCM cluster, you cannot use gatekeeper. Gatekeeper is only used between clusters.

If you follow the two cluster rule that I mentioned, you will have only two clusters and you really donot need a gatekeeper. Bandwidth management and call routing can be handled within the CCM easily.

If you intend to use Callmanager Express at some locations and have only one CCM cluster, then you may use Gatekeeper to do call routing and bandwidth management between the CME sites and the CCM cluster, and I think that would be worth it.

Hope this helps,

Partha

[arvind.krishna]

Thanks a ton Partha,

I have some doubts:

If i use two CCM clusters, do i compulsorily require a gatekeeper for intercluster communication?

Also since i need VoIP to work only in a CUG environment, what is the recommended MCS hardware considering device weights and the peak load in the worst case scenario?

[pbarman · Accepted solution]

Answering your first question, no you donot need a gatekeeper. Gatekeeper will do call routing and bandwidth management for you which can also be achieved within Callmanager using the route pattern, and Locations and Regions. With only two cluster I would not use gatekeeper.

For the MCS hardware, it really depends on the number of phones you want to register to the Callmanager, and BHCA (bust hour call attempts) which affects the device weight. I would suggest you look at CallManager design doc which has some good calculation for device weight, and it can be found at this link.

www.cisco.com/go/srnd

Check the "IP Telephony for Callmanager 3.3" pdf file.