Multi site SRST dial peers

[davidstillert]

So I've been working off and on building a new phone system for our remote sites and I've run into a mental block.  Each of the 4 remote sites which are configured in a full mesh VPN will get a 2921 router configured as an H323 gateway running CME as SRST with the auto attendant running locally on each router.  The main site has 1 pub and 2 subs.  I'm confused as to how many and what preference each dial peer should have.

Extensions Site 1: 21xx  Site 2: 22xx  Site 3: 23xx  Site 4: 24xx  Main site:  3xxx 4xxx 5xxx

Does each srst router need a dial peer to each UC server as well as each of the remote sites?  Keeping in mind an incoming pstn call from the remote site should be able to reach all 5 sites during non srst operation.

I haven't tested this yet however it looks like during normal operation a pstn call would automatically get sent to sub 1 however in WAN failure it would timeout across the 3 servers and get sent directly to the remote site srst router.

Do I need to tweak it to match on preference rather thant destination pattern?

SITE 1 DIAL PEERS

dial-peer voice 1001 voip
 description CUCM Sub#1
 preference 1
 destination-pattern [2-5]...
 session target ipv4:172.16.1.11
 voice-class codec 1
  no vad
!
dial-peer voice 1002 voip
 description CUCM Sub#2
 preference 2
 destination-pattern [2-5]...
 session target ipv4:172.16.1.12
 voice-class codec 1
 no vad
!
dial-peer voice 1003 voip
 description CUCM Pub
 preference 3
 destination-pattern [2-5]...
 session target ipv4:172.16.1.13
 voice-class codec 1
 no vad
!
dial-peer voice 2201 voip
 description Site 2
 preference 4
 destination-pattern 22..
 session target ipv4:192.168.2.10
 voice-class codec 1
 no vad
!
dial-peer voice 2301 voip
 description Site 3
 preference 4
 destination-pattern 23..
 session target ipv4:192.168.3.10
 voice-class codec 1
  no vad
!
dial-peer voice 2401 voip
 description Site 4
 preference 4
 destination-pattern 24..
 session target ipv4:192.168.4.10
 voice-class codec 1
 no vad

Any help would be appreciated.   If they didn't need the auto attendant at each site I would just run MGCP and make my life easier.

[Dennis Mink]

recapping what you said:

Extensions Site 1: 21xx  Site 2: 22xx  Site 3: 23xx  Site 4: 24xx  Main site:  3xxx 4xxx 5xxx

Does each srst router need a dial peer to each UC server as well as each of the remote sites?  Keeping in mind an incoming pstn call from the remote site should be able to reach all 5 sites during non srst operation.

-remember that for instance site 1 only needs knowledge of CUCM (or the redundant pair for that matter). This because CUCM has knowledge of the full dial plan. I cant really see a reason why you would want full mesh.

I haven't tested this yet however it looks like during normal operation a pstn call would automatically get sent to sub 1 however in WAN failure it would timeout across the 3 servers and get sent directly to the remote site srst router.

-yeah true, but how likely is it all servers are down at the same time? it is more likely that in the event that none of the servers are reachable from the gateway, you have no WAN link at that site, in which case you can't route calls directly to the sites using H323 dial peers.  definitely make it more simple than what you have now.

Do I need to tweak it to match on preference rather thant destination pattern?

preference only kicks in when there multiple dial peers that have  identical patterns. 

Please rate, if helpful