I'd like your thoughts on AVVID design in a WAN environment. I have a client with 13 offices. Each office connects to a central site via point-to-point T1 lines. The remote offices very in size from 10 - 150 users. What are your thoughts on installing a two CCM 3.3 cluster only in the central site and having PSTN gateways in each office? The goal is to centralize management, voice mail, have four digit dialing to anyone, and extension mobility.
The Voice mail will be Unity VM. I'm still not sure about unified nessaging because they still run GroupWise. If they migrate to Exchange, there would be an exchange server in each location.
Just to add to the mix. I plan on using SRST at each site that does not have a local CCM server. I see that SRST supports up to 240 phones these days.
If you do go with Unity/Exchange at remote sites, make sure to reserve some bandwidth for communication between the Unity and remote Exchange servers. If you dont, and there is congestion on the WAN, you will get prompt delays when checking messages.
Reserving about 16k per active call from the site is the recommendation.
Yes, but also checkout what hardware you need to run that many SRST phones. I beleive you need a 3660 series to support 240. A 2600 series will only support 48.
A 3700 series will support up to 144 phones. That would be the most I would need. All of the other sites could get by with a 2651XM which is the minimum gateway I would use anyway.
If your customer is interested in Unified Messaging with GroupWise check out TopCall.
I recently installed a system with a dual CM at the HQ with about 100 users and unified messaging. They have 23 remote site ranging from 5 to 50 users. The wan is made up of Frame Relay circuits with CIR ranging from 64k to 384k. Each site has its own analog lines for PSTN calls ranging from 4 analogs to a PRI. We used 1750s, 2600s and 3600s for the PSTN/SRST functions. They already had existing routers for the WAN so we left them in place (with QoS) so that if the router failed we didn't lose the wan and phones.
Things to plan for-
Bandwidth usage on the wan. Use regions/locations and QoS on the wan. You are in a better position with T-1s but it also depends on the number of calls needed.
DSP resources. You will need a hardware DSP to use things like MOH and Conference bridges across the WAN.
Dial Plan- You will need seperate Route Pattern partitions for each location so that they can use the local GW for calls.
911- Be careful about placement of the 911 Pattern, as you want to make sure any 911 call goes out the local Gateway.
MGCP vs. H.323 I have had better luck with H.323, I know SRST supports MGCP, but I find H.323 Gateways more reliable especially in a wan environment.
Just some things to start thinking about, maybe some others have more input. In general it sounds like a very solid design.
You may want to read through the basic design guide documents:
I'm on a project at the moment with 51 sites varying sizes 15-250 phones, remote gateways, centralised voice mail.
All I would say is plan out what you want to do first.
Examine your dial plan and look at things like the partitions and search spaces. Don't just dump all the users into the internal partition and then set them up with different search spaces, give each site it's own partition and then route between them with translation patterns. (this way you can configure your own version of AAR for WAN failure which Cisco doesn't claim to support)
Create a device pool for each site with different regions. set all inter region to be g.729( if you want to conserve bandwidth) and configure your locations correctly allowing only the number of calls that you want.
Stick with H.323 gateways, they may be more complicated in their configuration but they work better are easier to troubleshoot and support more interfaces.
But above everything else plan it all out and write it all down in a very big Excel spreadsheet / worksheets. Once you've got it down you can see if there are any mistakes without having to jump around tens of explorer windows.
Oh and don't believe everything you read, I've seen Cisco books claiming that there is no need to set the CSS for the phone and the line, yes there is and they have to be different if you want extension mobility between sites!
What's your approach to providing extension mobility for users who travel between sites when it comes to 999 provision ?
As far as I know there is a work around so that the callers emergency call will go though the 'local' gateway but it involves a bit of a hack from TAC.
You should be able to create multiple device profiles and associate them with the roaming user. Create a profile for each site and have the device settings appropriate for each site's local gateway. The user can select which profile to use when they log in to EM.
Cisco recommends using a so-called alternative dial plan for EM across the all sites. In this specfic design, you don't need mulitiple Device profile for each user. But the important thing you'll have to take care is dial plan. Basically you'll want to setup deny certain calls on the line CSS and allow all the calls on device CSS. Keep in mind, when you use EM you inherit everything from the device configuration, but with EM profile's line configuration.