CallManager 4.0(2a) Cluster

[tarun.pahuja]

Folks,

I have a Callmanager cluster 4.0(2a) which comprises of 1 publisher and 2 suscribers. Publisher and 1 subscriber is located at location A. Other Subscriber is located at location B. Location A and Location B are connected using a WAN link.

My question is how do i make sure that phones at Location B do not use CallManager cluster at Location A for registration and Call Control. Bascially, i do not want the phones to cross the WAN link and use resources from the Cluster located at Location A, as i want to provide total redundancy as far as CallManager cluster is concerned.

I thought by point the DHCP settings at Location B to the Subscriber at Location B would take care of this as the phones with register to Subscriber at Location B and use to for Call processing as well.

But Cisco Documentation confusses me when they talk about "CallManager Group" and "Device Pool".

Could someone elaborate on this and also advice me on how to do go about doing this?

Many thanks,

Tarun

[carijit]

Hi,

You have to create two Cisco Call Manager Groups with different Call Manager Servers as Primary Call Managers.

Say Call Manager Group 1 contains Subscriber 1 as primary and Call Manager Group 2 contains Subscriber 2 as Primary.

Now create two different Device Pools say DP1 and DP2.

Assign Call Manager Group1 to DP1 and Call Manager Group2 to DP2.

Register the phones at the remote location to DP2 and the local phones with DP1.

For load balancing and redundancy its better to have the all the call Managers in both the Call Manager Groups but just prioritizing the Call Manager server local to the segment as the primary call manager.

[thisisshanky]

Tarun,

If you have N callmanagers, how does the IP Phone select which callmanager to use first ?? Its only through CallManager Groups. A CCM group is an ordered list of Callmanagers prioritised top to bottom. A CCM group can be allocated to an IP Phone only through a Device Pool. Device pools are used to assign a set of common parameters to IPPhones and Gateways. One such common parameter is the CallManager group.

What you need to do is, to create two callmanager groups.

CCMGrpA and CCMGrpB.

CCMGrpA should list

Subscriber 1

Publisher

CCMGrpB should list

Subscriber 2

Create two device pools

Location1pool

->Point the Callmanager group CCMGrpA to this pool.

Location2pool

->Point the Callmanager group CCMGrpB to this pool.

For phones in Location 1, assign Location1pool as the Device pool.

For phones in Location 2, assign Location2pool as the Device pool.

This should help you achieve what you want to do.

The above design is not really recommended because IP Phones in Location 2 will be totally dead if Subscriber2 dies. Your Callmanager group should really be listing in the following order.

CCMGrpA

->Subscriber 1

Publisher

Subscriber 2

CCMGrp B

-->Subscriber 2

Publisher

Subscriber 1

Hope that helps!

[tarun.pahuja]

Thanks Guys, great answers!!!

Please correct me if i am wrong, as far as CallManager Groups and device pools are concerned, we are talking about call control and or processing.

These have nothing to do with phone registration. I mean, i would have to phyically assign the ip address of Subscriber B (Location B) on the DHCP server at Location B.

What is the point of the phones at Location B registering with the Publisher or the Subscriber at Locations A and using Subscriber 2 as call processing agent (device pool B).

Please correct me if i am wrong.

Thanks

[thisisshanky]

CallManager Groups have a major role in telling the IP Phone, to whom it should register.

Lets trace back a little bit on how phones register with callmanager. You configure your DHCP server with a pool of addresses to lease to the phones. Option 150 for this pool specifies the IP address of your TFTP server. The phone contacts the TFTP server (which is usually the publisher) and downloads a configuration file (xml format)..This configuration file contains the Callmanager Group information that you create. The IP Phone will register with the first callmanager specified in this Callmanager group.

For phones in Location B, the primary CM is Subscriber 2. What will happen to these phones if Subscriber 2 dies ??? There need to be a backup CallManager (either SRST on a router at location B or the CallManagers at Location A). There fore you should configure the Callmanager group for Location B in the following order...

Subscriber 2

Publisher

Subscriber 1

PS: Your TFTP server for Location B can be Subscriber 2. The TFTP server for Location A can be the Publisher.

Hope that makes sense..

[mlucas1911]

Think of DHCP as a layer below CallManager. The phone must execute the 'DHCP Request' and 'Ack' prior to the relationship with CCM. Your layer 2/3 network is where you control DHCP. You are correct, it's a bad design idea to come back to site A for an IP address that you'll never get if the link is down. You shoudl have a DHCP server at Site B for the phones at that location. MAke sure that each site specific DHCP server has the option 150 specified for the Publisher at Site A.

Hope this helps!

Mike Lucas