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Multiple Clusters with Unity


405. Can UTIM support the following setup?

One CM cluster but when you add the servers you have:

sub - CM cluster 1

sub - CM cluster 2

In the traditional setup base on white paper

I'm guessing if a whole CM cluster goes down, the other CM clusters are not effect due to creating a dedicate MWI and voicemail ports for each CM cluster

but in the new srnd, all traffic go through a single cluster with exception of mwi ports, so if that single CM cluster goes, all the other CM clusters will be effect. Is there a workaround?

2nd quest is 2 CM Cluster use the same Pilot Number and mwi on/off number?


New Member

Re: Multiple Clusters with Unity

Yes, you can still setup more than one port to a "second" cluster and have more than just MWI ports connected, as referenced by the old SRND. The new SRND just reflects a more optimum approach, in that you do not have to manually allocate a certain number of ports to cluster 1 and cluster 2, both clusters can share the same dial-in ports. The assumption with the new way is that the "first" cluster is highly redundant. However, you can still configure it the old way if you wish.

Your second question is also a yes, both clusters can use the same pilot DN and MWI on/off DNs.


Re: Multiple Clusters with Unity

Thanks for answering the 2nd ques but for the 1st ques, I don't think I was clear.


Let me define UTIM Cluster versus CM cluster. I will create ONLY ONE UTIM Cluster_A. Under this UTIM cluster, I'll have

Sub_1 CM Cluster 1

Pub_1 CM Cluster 1

Sub_2 CM Cluster 2

Pub_2 CM Cluster 2

Note: Utim Only shows one cluster but contains 2 diff CM clusters.

My rationale is that I want to mix the best of both worlds. The old method has a "somewhat" CCM cluster "Disaster Recovery" built in meaning that if CM cluster 1 goes down, it doesn't effect CM cluster 2 as far as unity is concern. The disadvantage was that ports were not scalable and you may have mwi broadcast to both CM Cluster.

To avoid the disadvantage of port scalability and mwi, the new srnd method introduce an optimum approach BUT all traffic goes thru a single CM cluster and subsequently introduce a disadvantage of a single point of failure (a whole cluster goes down). My client has experience recent natural disaster and the katrina incident has further allowed him to percieve a cm cluster failure as a "Single" GEOGRAPHICAL point of failure.


New Member

Re: Multiple Clusters with Unity

I think we are saying the same thing here. Maybe my answer before wasn't clear, but yes, you can have more than just the MWI port setup under the "second" cluster just as you could before, nothing has changed other than the SRND recommendation itself. So using six ports as an example:

Unity Port 1 : cluster 1 -> dial-in

Unity Port 2 : cluster 1 -> dial-in

Unity Port 3 : cluster 1 -> MWI/TRAP/dial-out

Unity Port 4 : cluster 2 -> dial-in

Unity Port 5 : cluster 2 -> dial-in

Unity Port 6 : cluster 2 -> MWI/TRAP/dial-out

The disadvantage of course is that the ports are statically allocated to a particular system.

And as an aside your terminology in UTIM is a slightly different than how it actually works. You have multiple "clusters" setup under a single "integration". You can only setup a single IP/CallManager "integration", under which you can enable multiple "clusters".


Re: Multiple Clusters with Unity

Sorry we are still talking 2 diff things.

On your example of the older method, if all CM in CM Cluster 1 dies, Unity can still support CM Cluster 2 for VM(Answering) and MWI(dialout)

In the new method, if all CM in CM Cluster 1 dies, Unity cannot support CM Cluster 2. The disadvantage of the new method is that CM Cluster 1 is the single point of failure for all CM clusters.

In order to get around the cons of newer method of losing the primary CM Cluster, I configured UTIM as One integration using the new method which seems to work:

UTIM (not CM) Cluster 1

ip add of sub - CM Cluster 1

ip add of pub - CM Cluster 1

ip add of sub - CM Cluster 2

ip add of pub - CM Cluster 2

*assuming 16 ports, ports 1-8 answering and 9-12 dialout

UTIM (not CM) Cluster 2

ip add of sub - CM Cluster 2

ip add of pub - CM Cluster 2

*port 13-16 dialout only

Notice that UTIM Cluster 1 has 2 DIFF CM clusters. When I simulate a CM cluster down by unplugging sub/pub of CM Cluster 1, CM Cluster 2 takes over.

I have not seen any doc or threads whether this method is supported and caveats.


Cisco Employee

Re: Multiple Clusters with Unity

Seems workable to me assuming you've got the call routing worked out. With this config there might be scenarious that'll put Unity in a state with some ports registered to cluster1 and some to cluster2.

I'd also suggest using the UTIM Cluster2 ports for MWI only. Outbound calls for TRaP and Notification might as well go out through the local CCM. When Unity places an outbound call its only prefence for select a port is top-down. So almost all of your outbound calls will go out port 16 and through the remote CCM.

Basically you're using CCM servers from the remote cluster as backup for the local cluster. Do you do a similar config with your phones? i.e. can you set the phones that normally register to cluster1 to look for a cluster2 server as a last resort? I guess i'm no expert on CCM topologies but in this case I wonder why have seperate clusters at all.

Also, I'm still suprised this level of reduncany is needed. Typically, Unity is colocated with at least on CCM server. If a geograpical disaster wipes out that CCM then the Unity server is probably gone too.



Re: Multiple Clusters with Unity

"there might be scenarious that'll put Unity in a state with some ports registered to cluster1 and some to cluster2"

--In UTIM, doesn't the setting "reconnect to the primary Cisco Callmanager server after failover is connect" avoid "some ports registering with C1 and some with C2"?

Do you do a similar config with your phones? No

We use separate Cluster cuz of IPCC Enterprise which best practice recommends a separate Cluster

In our case, Unity is not colocated. It is Colo with the AD stuff and there is a sonet back to CCM Cluster so they are in separate locations.

The only caveat to this redundancy is that although the conf are the same for both Clusters, the Hunt Pilot for Cluster 1 is 5555 but for Cluster 2 is *5555 so if C1 fails we have to do a MANUAL redundancy by removing the * and allowing C2 to use 5555. We are using H323 GW with preference commands to point to 5555

Cisco Employee

Re: Multiple Clusters with Unity

Ok, your topology is making sense to me now. I think the change in the recommended design was intended to account for the more common configuration where one cluster is local to Unity and the other is remote. For this setup, routing all calls through the local cluster optimizes WAN bandwidth and does not limit any redundancy.

For your config, where both clusters are remote to Unity, I see no benefit routing calls through a single cluster. You may be better served provisioning answer ports for both clusters. i.e. inbound calls from either C1 or C2 will go directly to Unity without routing through the other cluster.

You'll still see some inefficiencies in how Unity handles outbound dialing (TRaP and Notification). Unity will grab the first available outbound port for placing a call, regardless of which cluster the target is on. So outbound calls to a phone on C1 might get routed through C2. This is simply unavoidable at this point. Future version of Unity (or Connections) may address this. The best thing you can do for now is estimate which cluster expects the most outbound call traffic and arrange the clusters in UTIM so that ports for this cluster are listed last (highest numbered).

Another option to consider is to add a CCM sub for one of the clusters and have it collocated with Unity. If a PSTN gateway is also added here then you'd have additional redundancy. Even if your entire WAN is down, Unity would still be accessible through the PSTN.


Re: Multiple Clusters with Unity

Ok. Thanks for the confirmation. I wasn't sure why the SRND was recommending this method but it makes more sense now.

My followup question is this - assuming CM_C1 had more subscribers which leads to more Unity traffic and we are planning to upgrade to 32 ports. Ideally, I should use the older method and instead have:

UTIM Cluster 1

ip add of sub - CM Cluster 2 (less users)

ip add of pub - CM Cluster 2

*assuming 32 ports, port 1-6 answering and 7-8 (MWI, TRAP, NOTIF) and this is name UM1-VI_1-8

I have Failover set to UM2-VI_1-32

UTIM (not CM) Cluster 2

ip add of sub - CM Cluster 1 (more users)

ip add of pub - CM Cluster 1

ports 9-26 answering and 27-32(MWI, TRAP, NOTIF) and this is name UM3-VI_1-24


1. On UTIM_C1/CM_C2, it sounds like port 7-8 should ONLY be set to dedicated MWI (which I do not have set in the above example) as ports 27-32 is the higher ports would handle all TRAP/NOTIF as well as MWI for CM_C1?

2. If #1 is true, then a good rule of thumb is put the CM cluster with least amount of traffic as first in the UTIM_Cluster group?

3. On Callmanager, I plan to have the following setup:



UM2_VI_1-32 (for failover) or should I have UM2_1-8?



UM2_VI_1-32 (for failover) or should I have UM2_1-24?


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