CUCM Cluster issue Pub/Sub

[latintrpt]

Hello,

I think I have a slight issue with the way my cluster is set up.

I have one publisher and one subscriber.

They are both running 7.1.5.32020-1.

When our partner came in to do the initial build of the CUCM in their documentation it had said that all phones just be registered to the subscriber.  I just found this documentation again and apparently when phones were being registered, they were being registered to the publisher.

So right now as it stands, I have 765 phones that are registered to the publisher.  So something got screwed up.  I was wondering, will this type of setup mess anything up?  Can I leave things alone or should they all be pointing to the subscriber?  If the phones should be registered to the subscriber, what is the easiest way to do this?

Thanks

[Jaime Valencia]

The best practice in a 2 server cluster is that phones should be registered with the SUB.

All you need to do is change the CUCM group configuration and make SUB the 1st option and PUB the 2nd one.

This requires to reset the phones so plan accordingly.

HTH

java

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[latintrpt]

Thank You for the information.

How about for MGCP/H.323 Gateways and Route/Hunt Lists?

Should these also be registered to the subscriber?

Thanks

[Dennis Mink]

Yes I would primarily register everyting on the subscriber, including the GW's.and fail over to sub. You could choose to use the Pub as your TFTP server to spread a bit of load.

R.,

[Dennis Mink]

I meant fail over to publisher.

sorry

[latintrpt]

This looks like it will be a lot of work because we are a hospital and to switch over everything at one time would not fall

well with upper management.  If I kept everything on the publisher, would that cause a big problem in the future?  Currently we have 1126 devices registered to the publisher, including phones, gateways, route/hunt lists.

Thanks

[asandborgh]

Hi,

If you want to really understand the best practices (since it sounds like you will be living with this CUCM for awhile) read the appropriate sections of the SRND and for feature questions the Features and Services guide has excellent information  - more detailed in many ways - than the CUCM administration guide.

HTH,

Art

Features and Services Guide:

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/7_1_2/ccmfeat/fsgd-712-cm.html

Current CUCM SRND:

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/8x/uc8x.html

The SRND based on 7.X

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/7x/uc7_0.html

[latintrpt]

Thank You for the information.

I was just told that we will be adding 8 more subscribers to the cluster which make it a total of 10 Call Managers, yikes!!

So 1 PUB, 10 SUBS.

We currently have 1126 devices with more on the way.

What is the best way to design this out?  I know there can only be 3 call manager's in 1 call manager group.

[David Hailey]

First, a fully maxed cluster for 1126 devices is serious overkill unless you plan on adding several thousands more phones.  With that said, your cluster spec'd below is unsupported.  Cisco supports a maximum of 8 subscribers in a cluster.  Here's what you could do that is supported:

1 Publisher

2 Dedicated TFTP servers (they do not participate in call processing at all)

4 Active Subscribers

4 Backup Subscribers

Again, unless something has recently changed - you cannot have 10 subscribers in a cluster.  You will run into issues if you do this.

Hailey

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[asandborgh]

Just so there is no confusion, he actually might be getting 10 subs - Fom the SRND:

A Unified CM cluster may contain as many as 20 servers, of which a maximum of eight call processing subscribers (nodes running the Cisco CallManager Service) are allowed. The other server nodes within the cluster may be configured as a dedicated database publisher, dedicated TFTP subscriber, or media resource subscriber.

The other two might be media resource subs.

He also mentions that more phones/devices are on the way, which would explain why the cluster will be getting bigger.

latintrpt - you really want to get ALL of those devices off the pub.  Especially before you add to that cluster.  The pubs primary job is taking care of the database, not performing call processing.

HTH, Art

[Jaime Valencia]

Review this to fully understand the deployment models:

Unified Communications Deployment Models

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/8x/models.html

Art, for a cluster where you will have 10 servers it's out of the question not having dedicated TFTPs (as Hailey mentioned) and instead making the servers media resources standalone.

The Cisco TFTP service that provides this  functionality can be enabled on any server in the cluster. However, in a  cluster with more than 1250 users, other services might be impacted by  configuration changes that can cause the TFTP service to regenerate  configuration files. Therefore, Cisco recommends that you dedicate a  specific subscriber node to the TFTP service, as shown in Figure 8-1,  for a cluster with more than 1250 users or any features that cause  frequent configuration changes.

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/8x/callpros.html

If they need standalone media resource servers, then they need to add more servers.

The word subscriber is most often related to call procesing servers but they can do other stuff, I'mg guessing Hailey thought they might want 10 call processing server which is not supported.

Subscriber nodes include Unified CM call  processing subscriber nodes, TFTP subscriber nodes, and media resource  subscriber nodes that provide functions such as conferencing and music  on hold (MoH).

In a cluster where there will be 11 servers what we would support is the design Hailey mentioned.

If you need more than 8 call processing servers and just go ahead and do the deployment this won't be supported. If you want support, we have a specialized team on that, but they need to analyze all the requirements from your network and determine that you really need a super-cluster

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[asandborgh]

Hi Java,

Totally agree - that's why I suggested he read the SRND (THE design bible).  Also agree that "subscriber" has become somewhat synonymous with a call processing member of the cluster when in reality they are subscribers to the pubs database and can play other roles.  When i had my first CCM training on version 2.4 it was covered pretty thouroghly because the SQL subscriptions were, well, not always exactly stable.

Considering he is new to this I was just trying to point out that subs don't necessarily need to process calls.  And yes at least one dedicated TFTP would be appropriate if they are going to scale to 8 call processing subs.

I think we are in violent agrrement here  ; ^))

Cheers!

Art

[David Hailey]

FYI - one reason I was so quick to point out that 10 subscribers (i.e., call processing nodes) is not supported is because Java and I teamed up on an issue the other day where someone had something like 9 standard subscribers and they were experiencing some pretty quirky issues with DB replication and state...it was pretty clear to us after reading the issues/symptoms that this was likely caused by an unsupported configuration.  So, from an architecture perspective - I think that's been laid out pretty well.  I've actually designed, implemented, and supported a supercluster at a previous company. At that time, it was about 15,000 nodes which was considered extremely large back then.  I can tell you from experience that if they are going to grow to a size that actually warrants a supercluster then they will want 2 dedicated TFTP servers.

Hailey

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[latintrpt]

Thank You all for the valubale information.  I'll have to think about how I want to design this out.

When adding a sub to be a dedicated TFTP server, what all do I need to do so that phones point to these subs?  I don't want these servers to be doing any kind of call control.  Do I also have to add these TFTP subs to a call manager group?

Thank You again

[Jaime Valencia]

Add the SUB with the regular procedure, there is nothing special about the install of any kind of subscriber.

Just don't enable and start the CUCM service on it, just make sure TFTP is enabled and running.

Then point phones to it as the TFTP address.

No, you don't need to add it to a CUCM group, and you couldn't even if you wanted, since only servers where ccm is running show up there.

HTH

java

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