When is it necessary to have multiple Cisco Call Manager Clusters. The only necessity I would think is when a client has more than 30,000 IP Phones requirements. Is it beneficial to have multiple Call Manager Clusters other than IP Phones more than 30,000.
I have a customer who have probably less than 1000 thousand IP Phones, and requiring multiple Clusters for Disaster Recovery Plan. To me, Mutliple Clusters have nothing to do with real Disaster because if they are looking for Disaster Recovery than they have to opt for Clustering over IP WAN Model.
Probably your client is confused with a terminology. Cluster is "independent entity" - in the cluster you have your own settings, users database, call routing, gateways, etc. And WITHIN the cluster you may have multiple servers, which build the cluster. Cluster consists of one Publisher and one or more Subscribers. The Publisher is primary repository for all information within the cluster, when Subscribers use this information to serve to clients.
The problem with DR could be losing the Publisher. But it's not so scary - your Subscribers will work independently and serve all clients. All you will loose - ability to make any changes to your VoIP environment (for example, add or change clients).
From the practical standpoint, for DR you could have one Publisher and one Subscriber in one location, and two Subscribers in another location. You should either do regular backups of your Publisher databases, or swap and store one hard drive (if you have RAID). If your "data center" is gone, you may either install a CallManager Publisher on one server in the remote location and restore all databases from the backup, or insert "backup hard drive" and boot the server from that drive. Sure, in this case you have to change some systems parameters i.e. IP address, CallManager parameters, etc.
The 30,000 IP phones in a cluster is used by Cisco marketing, in reality you would go to about half of that.
But to answer your question, a good example of why you would configure seperate clusters is Call Center site. In order to Integrate IPCC Enterprise or Express with CCM it needs to be tested and approved by Cisco development team, sometime it takes several months before a particular version of CCM can be integrated with IPCC, so customer that wants to upgrade to the latest CCM would need to wait before IPCC is approved. If you configure a seperate CCM clsuter for your Call Center, the rest of the organization will be independant of it.
The short answer is that you don't.... That isn't entirely true while at
the same time it kind of is, but for the most part you don't configure
the softkeys. You enable or disable them via TCL. Here is the long
answer. Be sure to read the whole thing or e...
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