CIPT1 - Max Cluster Size/Active Call Processing

So I am reading the AS-SG for the CIPT1 material and have a question...

Max of 20 servers in a single cluster...understood.
1 Pub...gotcha.

This is where I am having trouble...

8 total subs, but only 4 can actively handle calls, or so the book says...

Does this mean you can add 8 MCS devices as a sub, but only 4 of them can have ccm.exe running? One of the deployment models (Clustering over the IP WAN with Remote Failover) says the following, though:

" Each of the sites contains at least one primary Unified CM subscriber and may or may not have a backup subscriber. This model allows for a deployment of up to eight sites, with IP phones and other devices normally registered to a local subscriber when using 1:1 redundancy and the 50/50 load balancing option..."

So can 4 or 8 actively handle calls?

If that is the case what the other 11 servers doing? Are they not added as subs when initially configured? Do they just provide other resources that the 8 subs aren't providing?

My questions runneth over...

Any help straightening this out in my head would be greatly appreciated!

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FattyAcid

jezg76 wrote: »

So I am reading the AS-SG for the CIPT1 material and have a question...

Max of 20 servers in a single cluster...understood.
1 Pub...gotcha.

This is where I am having trouble...

8 total subs, but only 4 can actively handle calls, or so the book says...

Does this mean you can add 8 MCS devices as a sub, but only 4 of them can have ccm.exe running? One of the deployment models (Clustering over the IP WAN with Remote Failover) says the following, though:

" Each of the sites contains at least one primary Unified CM subscriber and may or may not have a backup subscriber. This model allows for a deployment of up to eight sites, with IP phones and other devices normally registered to a local subscriber when using 1:1 redundancy and the 50/50 load balancing option..."

So can 4 or 8 actively handle calls?

If that is the case what the other 11 servers doing? Are they not added as subs when initially configured? Do they just provide other resources that the 8 subs aren't providing?

My questions runneth over...

Any help straightening this out in my head would be greatly appreciated!

I think the book is wrong. My understanding (or how I'm learned) is that you can 20 servers in the cluster. ALL the servers are either a publisher (one) or a subscriber (even if they're just TFTP, MoH server, etc.). And eight of those subscriber servers can have the CallManager Service active and process calls.

pitviper

I found the documentation to be a little vague. According to the SRND, you can only have 8 subscribers in the cluster and of the 8, only 4 will actively handle call processing with the other 4 operating in a hot standby (backup) mode.

The other servers (media resources, CTI, TFTP and so on) don’t need to run the call manager service.

Here’s what the SRND has to say about a clustered "Remote Failover" deployment (I'm not sure that all 8 are active at a time, just capable of call processing. The documentation is not clear in this scenario IMHO)

Remote Failover Deployment Model
The remote failover deployment model provides flexibility for the placement of backup servers. Each of the sites contains at least one primary Unified CM subscriber and may or may not have a backup subscriber. This model allows for a deployment of up to eight sites, with IP phones and other devices normally registered to a local subscriber when using 1:1 redundancy and the 50/50 load balancing option described in the chapter on Call Processing, page 8-1. Backup subscribers are located across the WAN at one or more of the other sites. (See Figure 2-7.)

When implementing the remote failover model, observe all guidelines for the local failover model (see Local Failover Deployment Model), with the following modifications:

• Configure each site to contain at least one primary Unified CM subscriber and an optional backup subscriber as desired. If a backup subscriber over the IP WAN is not desired, a Survivable Remote Site Telephony (SRST) router may be used as a backup call processing agent.
• You may configure Unified CM groups and device pools to allow devices to register with servers over the WAN.
• Signaling or call control traffic requires bandwidth when devices are registered across the WAN with a remote Unified CM server in the same cluster. This bandwidth might be more than the ICCS traffic and should be calculated using the bandwidth provisioning calculations for signaling, as described in Bandwidth Provisioning, page 3-58.

Note You can also combine the features of these two types of deployments for disaster recovery purposes. For example, Unified CM groups permit configuring up to three servers (primary, secondary and tertiary). Therefore, you can configure the Unified CM groups to have primary and secondary servers that are located at the same site and the tertiary server at a remote site over the WAN.

FattyAcid

pitviper wrote: »

I found the documentation to be a little vague. According to the SRND, you can only have 8 subscribers in the cluster and of the 8, only 4 will actively handle call processing with the other 4 operating in a hot standby (backup) mode.

I still think this is all wrong.

IMO, very server in the cluster except the publisher is a subscriber. They all have the Informix IDS database, thus they're involved in a database replication.

So every CTI Manager, TFTP Server, Conference server, MoH server, etc. are all susbscribers.