11-30-2011 04:40 AM - edited 03-19-2019 04:02 AM
Hi all,
We have three CUCM servers, 1x Pub and 2x Subs. Both subs are identified in the 'CMG' (CallManager Group). The DP for this site is linked to the CMG. All the site phones are in the DP.
Within the CMG, how exactly does CUCM loadbalance the IP phones ?
We will be powering one server off via the OS Admin > version > shutdown GUI. We need to replace a failed hard drive in the server (RAID1+) i think - two logical drives, each with 2 disks where the second mirrors the first.
I'm curious to understand how CUCM will react when we power one of the two subscribers off. In theory any IP phones that try to make a call after this will automatically use the second subscriber in the CMG. But how does CUCM loadbalance/regulate which member of a CMG an IP phone contacts? Is there a Service setting such as round robin ?? Also, am i correct in assuming that because the IP phones are registered currently, they wont de-register or blip when we power a subscriber off? (I expect any active calls might drop though)
Rgds
Solved! Go to Solution.
11-30-2011 06:17 AM
Hi Andy,
The phones will always try to register with the first member of the CCM Group
and if it is unavailable they try the second member and finally the third.
So if your CCM Group looks like
Sub 1
Sub 2
Pub
The phones that reference this CCM Group (via their Device Pool settings)
will try Sub 1 first and if it is unavailable they try Sub 2 and if it is unavailable they try
Pub. So if in our example, it is Sub 1 that needs to be shut down the phones will all
fail over to Sub 2 when you shut down Sub 1. You can also re-order the CCM Group
ahead of time to look like;
Sub 2
Sub 1
Pub
And bounce the phones so that they are all registered to Sub 2 ahead of time.This way
they won't take a hit. Active calls will remain up until call completion in either scenario
Cheers!
Rob
11-30-2011 06:17 AM
Hi Andy,
The phones will always try to register with the first member of the CCM Group
and if it is unavailable they try the second member and finally the third.
So if your CCM Group looks like
Sub 1
Sub 2
Pub
The phones that reference this CCM Group (via their Device Pool settings)
will try Sub 1 first and if it is unavailable they try Sub 2 and if it is unavailable they try
Pub. So if in our example, it is Sub 1 that needs to be shut down the phones will all
fail over to Sub 2 when you shut down Sub 1. You can also re-order the CCM Group
ahead of time to look like;
Sub 2
Sub 1
Pub
And bounce the phones so that they are all registered to Sub 2 ahead of time.This way
they won't take a hit. Active calls will remain up until call completion in either scenario
Cheers!
Rob
12-01-2011 09:10 AM
Thanks Rob. Concise and quick response as always! Much appreciated!
We have the disk-swop instructions from Cisco TAC so hopefully (if that goes smoothly out of hours) the re-register of the phones wont matter. Infact, it will be a good test of the failover capabilities of the CM Group
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