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Many Questions about Large Scale Deployment

After browsing through some of the SRND documentation, there are many questions in my mind about large scale deployment.

Assume I have an extremely large number of users (few hundred thousand) dispersed throughout the globe where some sites have more than 60,000 users and others have less than 60,000.

1. Would Multisite with Distributed Call Processing be the best option for deployment?

2. Since a single call manager cluster has a soft limit of 60,000 users and 30,000 endpoints - how would I setup CUCM at sites with more than 60k users? How many CUCMs can be clustered together?

3. If I want to use an application such as CUPS across the enterprise - would it be possible to enable IM/Chat capabilities and presence for ALL users across the entire enterprise or would this have to be set up as disparate systems across all of the sites?

4. Suppose I have a traveling user that constantly moves between a large site and a small site. Would he be able to move between the sites and just log into a phone or IM/Chat no matter what site he is in?

5. How would I incorporate MeetingPlace/VTC into this environment?

Tommer Catlin

Quick responses to your questions.

- Typically, you will have a cluster in Americas, Asia Pacific, APT and Europe.   You are basically taking the clusters and putting them into regions.

- Each CUCM cluster will its own CUPS cluster.  The CUPS servers and inter-cluster and exchange information such as IM, users, etc.

- A user going from site to site to site does not matter.  If they are using Extension Mobility, they will have to stay on the same cluster. But if they were using IP Communicator or CUPC client, it does not matter where they are... they have a phone and IM on their laptop.

- MeetingPlace is simply an audio gateway.   Anyone in the clusters can use MeetingPlace. 

- for dialing between clusters, Id recommend a gatekeeper to manage the calls. 

- Read up on the SRND guide for CUCM.  It will give you an idea of how to size your clusters and the number of servers required to run what you are looking at.

A few things I want to add here:

  1. Extension Mobility between clusters is natively supported in UCM 8.0; it is called Cross-Cluster Extension Mobility.
    This will allow a user to log in to any phone at any site in the organization.
  2. The new Service Advertisement Framework (SAF) feature for Cisco IOS allows you to advertise directory numbers between clusters and greatly simplify the way that inter-cluster dialing configuration would work. You will likely want to use a Cisco Unified Border Element (CUBE) in tandem with this to ensure that bandwidth utilization is properly tracked between clusters.
  3. Alternatively, if you do not have a viable global WAN with sufficient bandwidth on it, you could utilize the Cisco Intercompany Media Engine to transparently and securely route calls between clusters across the Internet.
  4. Ensure that you locate a partner or internal deployment staff who are well versed in the E.164 dial plan that was introduced in UCM 7. It will be hugely advantageous in a deployment of this scale.
  5. I strongly recommend you work with a Cisco partner to properly design the solution. The software has specific and very granular limitations. Partners have access to tools which can assist in properly sizing the equipment for your environment.

Great approach.  There is soo many new things in 8.0 that I have not tried yet.....  especially on a global scale much less locally.    Using a partner is highly recommended.

Is CUBE replacing gatekeepers in the long run?   I did not  know CAC could be advertised to CUBEs as a solution between sites/clusters.

Suppose I have an enterprise LDAP directory with 300k+ users, how would authentication work across multiple geographically dispersed clusters? My understanding is that a single cluster can only import 60,000 user profiles before it starts adversely affecting performance.

Your numbers do not make sense.

If a cluster can support 30,000 phones (hypothetically) and you have 300,000 LDAP users, you will not be using more than 30,000 authentications at any given one time.

You need start with a low level design and come up with the hardware/software and business requirements to make this work.   Geographical locations come into play for redudancy, sizing and diaster recovery.   And again, most enterprise customers will have multiply stand alone clusters (8 servers per cluster) in each region of the world depending on the business requirements.

Each cluster will have its own connection to LDAP for the directory and authentication.   If you are running a single forest for 300k users?  Or is it a multi-forest, multi-domain enviroment.  All these items come into play when you actually sit down do the design from the ground up.

  You will not have 30,000 Extension Mobility devices on a single cluster.  Its not possible and would crash the system.

You also do not want to max out a cluster for devices and users.   If a subscriber fails, you will be over loaded on the backup CUCM. 

There is a section on how LDAP works with CUCM cluster.  Cross cluster and CUCM 8.x I have not tried yet, possibly others may have

Would it still be possible to have IM/Chat cross-domain for ALL users in a multi-domain/multi-forest environment along with directory search capabilities?

If so, how would that be possible?

Rob Huffman
Hall of Fame Community Legend

Hey TCAT & Jonathan,

+5 points each for your excellent insight and tips



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