I'm new to cisco VoIP and also new to the company I am at so I am unaware of what to look for.
I need to change the DNS configuration on the call managers on our network.
We have 1 publisher and 3 subscribers, managing about 2000 phones in total.
I have read documentation online on how to change the DNS configurations, and that I need to restart the Tomcat service, and also restart the server.
My concern is failover issues.
What I want to know is, what happens when I change the DNS on one call manager and then reboot it. Will those phones be out of service while it reboots or will they failover temporarily to another subscriber?
Likewise, what happens when I change the settings on the Publisher?
Call Manager is version 6.1.3
Groups and clusters form logical collections of Cisco Unified CallManager servers and their associated devices. Groups and clusters do not necessarily relate to the physical locations of any of their members. A group comprises a prioritized list of up to three Cisco Unified CallManager servers. You can associate each group with one or more device pools to provide call-processing redundancy. You use Cisco Unified CallManager Administration to define the groups, to specify which Cisco Unified CallManager servers belong to each group, and to assign a Cisco Unified CallManager group to each device pool. Each group must contain a primary Cisco Unified CallManager, and it may contain one or two backup Cisco Unified CallManager servers. The order in which you list the Cisco Unified CallManager servers in a group determines the priority order.
Cisco Unified CallManager groups provide both redundancy and recovery:
•Failover—Occurs when the primary Cisco Unified CallManager in a group fails, and the devices reregister with the backup Cisco Unified CallManager in that group.
•Fallback—Occurs when a failed primary Cisco Unified CallManager comes back into service, and the devices in that group reregister with the primary Cisco Unified CallManager.
Under normal operation, the primary Cisco Unified CallManager in a group controls call processing for all the registered devices (such as phones and gateways) that are associated with that group.
If the primary Cisco Unified CallManager fails for any reason, the first backup Cisco Unified CallManager in the group takes control of the devices that were registered with the primary Cisco Unified CallManager. If you specify a second backup Cisco Unified CallManager for the group, it takes control of the devices if both the primary and the first backup Cisco Unified CallManager servers fail.
When a failed primary Cisco Unified CallManager comes back into service, it takes control of the group again, and the devices in that group automatically reregister with the primary Cisco Unified CallManager.
Hope it helps.
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Thank you, could you possibly answer another question or two?
Since I want to change the DNS on the call managers, in what order should I do it? Publisher first? or Subscriber first?
I was told the last time this was attempted at this business that after DNS servers were changed and the machines rebooted, the Call managers wouldn't talk to one another anymore.
Are there steps to avoid this?
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One more question;
I cannot find any information regarding whether I should change the DNS settings on the Publisher first, or ont he subscribers.
AFAIK it really shouldn't make any difference on which one you start.
if this helps, please rate
Ideally as Jamie said it shouldn't matter.I would ideally do it on the pub first and then the sub. If you are planning to add domain check the forward and reverse look up on yr dns servers is configured correctly
Also if domain is make sure that utils network resolves correctly from pub sub else you might have DB replication issues