This is a post intended to help others who are implementing multi-site over an MPLS or pre-existing VPN connection. I am currently finishing one such implementation and found that it was necessary to gather information from several different sources to put all of the puzzle pieces together. This is how I made it work in my particular environment.
Both sites have identical equipment and software versions:
* UC560 with PRI
* Software pack 8.1.0
* CME 8.1
* Voicemail version 8.0.3
* Locale is US English
* 3-digit extensions
* 79xx series phones
* Configured using Telephony Setup Wizard on CCA 3.1.1
The extension range of Site A is 150-199. The extension range of Site B is 200-299. After much reading I decided that using non-overlapping extension ranges across the sites will make things much easier to configure and much less confusing for the users.
Both sites are connected via MPLS so I am not concerned with the details of VPN setup. If you have a pre-existing VPN connection or MPLS connection we will assume that it is working correctly.
* The WAN interface of each UC560 is not used
* Firewall and NAT are disabled
* The default gateway at each site is the MPLS router
Networking for Site A is as follows:
* VLAN1 192.168.10.60/24
* VLAN100 10.1.100.1/24
* Gateway 192.168.10.1
Networking setup for Site B is as follows:
* VLAN1 192.168.20.60/24
* VLAN100 10.1.200.1/24
* Gateway 192.168.20.1
CCA did not correctly set the default gateway on either device. This had to be manually added to each UC560 using the following commands and Site A and Site B respectively:
ip route 0.0.0.0 0.0.0.0 192.168.10.1 permanent
ip route 0.0.0.0 0.0.0.0 192.168.20.1 permanent
If everything is working correctly you should be able to ping the VLAN1 address of the UC560 in Site A from the command line of the UC560 in Site B and vice-versa. Figure this out before you proceed (this is how I found that the default gateway was not set correctly).
Now we configure the dial peer at Site A. Note that the dial peer number that you use is up to you. I chose to use a dial peer number of 6000 because it looks like it is beyond the range that the CCA will be using when creating dial peers. I found documentation that indicated anything above 5000 would work but I saw that CCA used 5000 for a BACD group that I had created. To be safe I went to 6000 but since the out of band configuration documentation is no longer available I do not know that 6000 is the best. Check your dial peer numbers from the command line using this command:
show run | sec dial-peer voice
Once you're sure that 6000 (or the number you chose) is not use in, here is the dial peer setup for Site A:
config t
dial-peer voice 6000 voip
description CALLS FROM SITE A TO SITE B
destination-pattern 2..
session target ipv4:192.168.20.1
dtmf-relay h245-alphanumeric
codec g711ulaw
no vad
The important parts are the destination-pattern and session target. This is where having non-overlapping extension ranges across sites is helping us. We are telling site A that any three digit extension that starts with a 2 should be sent to the VLAN1 address of the UC560 at Site B.
And the dial peer setup for Site B:
config t
dial-peer voice 6000 voip
description CALLS FROM SITE B TO SITE A
destination-pattern 1[5-9].
session target ipv4:192.168.10.1
dtmf-relay h245-alphanumeric
codec g711ulaw
no vad
Again, we are telling Site B that any three digit extension that begins with 15, 16, 17, 18, or 19 should be sent to the VLAN1 address of the UC560 at Site A (remember, Site A has an extension range of 150-199).
The codec and "no vad" settings are pretty well agreed upon across all of the documentation that I have seen. I don't claim to understand why "no vad" is important, but at this point you should be able to pick up a phone at Site A and talk to somebody at Site B by dialing their extension (and vice versa).
If your MPLS provider is handling QoS like mine is (TelePacific recommended 'ef') you could tag your traffic appropriately by editing your dial-peer configuration to look something like this (notice the line that begins with ip qos). I have not confirmed that this is appropriate or has any effect on quality:
config t
dial-peer voice 6000 voip
description CALLS FROM SITE A TO SITE B
destination-pattern 2..
session target ipv4:192.168.20.1
dtmf-relay h245-alphanumeric
ip qos dscp ef media
codec g711ulaw
no vad
Now you might think you are finished but if you make a call extension 201 at Site B from Site A and let that call go to voicemail, you will get a message indicating that there is no mailbox at the extension. You know that you did configure a mailbox for extension 201 so why is this happening? The call the voicemail at 399 is coming back to your local UC560 in Site A. Here is the fix:
config t
voice service voip
no supplementary-service h450.2
no supplementary-service h450.3
Now when you dial extension 201 at Site B from Site A it will go to the correct voicemail box.
There may be things that I have missed and other little "gotchas" that are yet to come but so far this has worked well and provided the following benefits:
* Simplified multisite dialing rules (no 8 + site index + extension)
* Simplified networking (did not need WAN interface due to MPLS)
Drawbacks so far:
* Cannot use CCA multisite manager
I hope that that somebody finds this information helpful someday. I will continue to add to this over the next week as issues come up.
