help with CUCM cluster design

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Jul 7th, 2008
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Hello


I am designing a CUCM 6.1 cluster with 2 CUCM 6.1 servers and a Unity server.


As I am new to clustered CUCM solutions, I have a few things that I am uncertain about, and hope that someone are willing to help me.


- I wan't to do some kind of load balancing on the 2 CUCM's, so that in the event of failure, only about 50% of my production is impaired. And as I have read in the SRND on CUCM 6.1, this scenario is possible - correct ?

- I would like to have redundant Voice Gateways. Like fx. 2x Cisco 2821, each with a PRI E1 ISDN module, and hereby routing calls through these 2 gateways. In the event of failure on one of the gateways, I would like to automaticly have all calls routed through the remaining gateway. But how do I do this and is it possible? Do I have to use the gatekeeper functionality.

- regarding codecs. I want to use G.711 internally on all sites, but on calls between sites, I want to use G.729. As I have heard, this consumes DSP resources on the voice gateway - is that correct ? and how many ?



Thanks in advance for any help

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Chris Deren Mon, 07/07/2008 - 06:01
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Yes, this is definitely supported, however since you only have 2 servers I would not recommand load balancing as one of your servers is the CM Publisher, I would recommand using the publisher as a backup to the primary call processing subscriber. How many phones is this environment going to have?


You can use redundant GWs for outbound calls by configuring Route Groups/Route Lists in such as way. No need for a GK.


It requires additional DSPs only if the calls are going to arrive/go out on PRIs and traverse the WAN, if the call are only between IP phones no need for additional DSPs. For calls to centrelized Unity system you may either use hardware DSPs configured as transcoders or native Unity transcoding or you can install Unity with G729 codec and not worry about transcoding at all. Each g729 call utilizes twice as many DSPs as G711 call.


HTH,


Chris

rasmusan1 Mon, 07/07/2008 - 06:08
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Hi Chris


thank you very much for quick and informative reply !


- I see your point, regarding using the publisher as the backup. How many phones will this setup appromixately support, using MCS 7825 servers?


- about 250 phones will be registered in this environment.


- what would you recommend to be the best design, regarding the use of codecs? I will have a centralized Unity server.


- for the unity server, do you think that a MCS 7815 server would be powerfull enough to host voicemail for 250 users ?

Chris Deren Mon, 07/07/2008 - 06:24
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- You should be able to support about 1000 phones per server or so depending on other components in the cluster, i.e. number of GW, etc. Use the capacity calculator to ensure your enviroenmnt will support it:

http://www.cisco.com/cgi-bin/CT/PGWCT/ct.cgi


- You should be fine


- Is it Unified or VM only deployment? With VM only I would recommand G729 for Unity as it is less storage and it's hard to tell the difference, with UM I would use G711 to store maeeages as you can play the message from any PC, with G729 you would need to install the codec on the machines


- I have 7815s, I would only install Unity on 7835 or 7845 to at least get 2 power supplies. At minimum I would recommand 7825.


HTH,


Chris

rasmusan1 Mon, 07/07/2008 - 06:46
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thanks again for great reply !



- ehm not sure what Unified and VM is ? and the difference ?

- I'm a little confused. You say that you have 7815's but would only recommend 7825. Do you think that a 7815 would be enough ?

Chris Deren Mon, 07/07/2008 - 07:11
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- UM is unified messaging, where Unity is integrated with corporate Messaging platform and it allows you to receive voicemail in your email client, VM is voicemail only solution where a dedicated message store is deployed and the only way to check VMs is via the phone


- 7915 will suffice, however I simply dont like it :-)

Here is a good reference doc for Unity platforms:

http://www.cisco.com/en/US/prod/collateral/voicesw/ps6789/ps5745/ps2237/product_data_sheet0900aecd802132ef.pdf


HTH, please rate all useful posts!


Chris

rasmusan1 Mon, 07/07/2008 - 23:57
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Hi Chris



Once again thank you for reply.



- If i wan't to do an integration with Cisco Unity Connection instead of Cisco Unity. Is this possible and what features do i loose by choose the Unity Connection ?

- what server would tyou recommend running the Unity Connection on ?

Ayodeji Okanlawon Tue, 07/08/2008 - 00:50
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Hi,


Yes, you can intergrate Unity Connection (UC) with CUCM6.x....


The main difference between UC and Unity is that UC does not support Unified messaging while Unity does support it...


What this means is that when a user leaves a voice message for another user, it will not be sent into their email as a voice mail attachment. This you can do with unity.


However, you can configure an IMAP connection between exchange and UC. This way when people press the message button on their phone to listen to their voice mails, UC can read their email messages to them via TTS on the phone...


Enabling IMAP Access to Exchange


Cisco Unity Connection uses the IMAP protocol to access e-mails in Exchange so the messages can be played by using TTS. By default, Exchange is not configured to allow IMAP access to messages.


The latest version of UC is UC 2.1..Have a look here for documentation on UC..


http://cisco.com/en/US/products/ps6509/prod_installation_guides_list.html

tommyrosamilia Wed, 07/09/2008 - 10:17
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I am looking for a Design guide for Unity Connection. Can't seem to find it.

I need to know if Unity Connection is supported across a WAN from CUCM

Chris Deren Wed, 07/09/2008 - 11:14
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Yes it is supported, the think you need to ensure is that you have enough bandwidth for all of you VM ports. So, assume you have 32 ports defined in CUC with G729 codec, you will require at least 32 * 30kbps of bandwidth to guarantee for CUC.


HTH,


Chris

Ayodeji Okanlawon Mon, 07/07/2008 - 07:43
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Hi,


Here are possible answers to your questions/concerns..


1. Callmanager provides a high level of resiliency..hence you can achieve both load balancing and resiliency at the same time...


1. To answer your first questions correctly, I will need to know how many ip phones you are deploying and what model of MCS server you are using...


If you have users less than 1,000 and you have a minimum of mcs 7825 then all you need to do is to use the CCM group to setup resiliency for your cluster...


You will configure your CCM group as followins....


Primary call processing server: subscriber

Failover call processing server: publisher (that implies that you will have to activae the CCm service on your publisher too)


Hence when anything goes wrong with your subscriber, your publisher will take over call processing functionality without any disruption to your network...


NB: If you have a cluster that has over 5,000 users then this will not be appriopriate...



2. For your voice gateways, yes this is possible. Within callmanager you can setup Route Groups..in each route group you can have more than one voice gateway...


Please note that For h.323 gateways if your isdn goes down on one of the gateways ( and Ip connectivity is up between the gateway and callmanager) you will need to adjust your call routing parameters under callmanager service parameters for automatic failover to happen......


I suggest you look at the admin guide for CCm6.1 to know how to configure Route groups and gateways..


You can also configure HSRP if the gateways are the default gateways for your network..


Regarding Codecs....For calls between sites ( if they are over your WAN) then no dsp is required. callmanager will use the codec setting you have configured in your regions to make calls to other sites...


Hope this helped a little.



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