What type of trunk do I use?

[robertcrabbe]

I'm new to CallManager and IP Telephoney so these might be stupid questions.

I have 3 campuses interconnected via full mesh DS3s.

For example:

A <- DS3 -> B

A <- DS3 -> C

B <- DS3 -> C

I have a 7206 at each site.

I currently have a CallManager cluster at site A running version 3.3(3).

We plan to set up two additional clusters - 1 at site B and another at site C. We plan to implement 3.3(3) at each site.

Upgrading at this point is not an option.

My question is this:

(1) Given the above scenario, what is the best method to set up inter-site and toll bypass communication over the WAN?

(2) Should I use Intercluster trunks, H.225 Gatekeeper-Controlled Trunk, or Intercluster Gatekeeper-Controlled Trunk?

(3) If I use H.225 Gatekeeper-Controlled Trunk or Intercluster Gatekeeper-Controlled Trunk, do I configure site A's 7200 as the Gatekeeper for site A's CallManager, site B's 7200 as the Gatekeeper for site B's CallManager, and site C's 7200 as the Gatekeeper for site C's CallManager, or do pick one and make it the Gatekeeper for all of them?

Can you point me to any documentation.

I'm looking at the SRND for CallManager 3.3, but there isn't an example there that specifically addresses a full mesh WAN as I have.

I'm having trouble finding much in the way of examples and/or documentation.

Your help is greatly appreciated.

[thomas.chen]

Intercluster trunks should be a good option here. you can refer to this links: http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_administration_guide_chapter09186a00801821d4.html

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_administration_guide_chapter09186a0080182480.html

[robertcrabbe]

Thank you for your reply.

Just to make sure I understand you correctly, you would use an Intercluster Trunk without Gatekeeper control. Is this correct?

What is you reasoning behind it? What are the advantages and disadvantages of using either method? In what situations would gatekeeper controlled trunks be preferred over non-gatekeeper controlled trunks, and vice versa?

Thanks

[lfulgenzi]

When you use an intercluster turnk without gatekeeper control, you have to make sure that the trunk is registered to a server that the phones can communicate with, I believe that it only has to be in the call manager group, they do not have to be registered to it.

For example, I had an intercluster trunk from one publisher to another, but because the publisher in one cluster was not in the call manager group of any of the phones, it would not work.

With a gatekeeper controlled ICT, you don't have to worry about this. Also, with gatekeeper controlled, you would need only one trunk per cluster, not a full mesh.

I could be wrong with this, but I'm pretty sure that's how it works.