Switchback to Call Agent (CUCM): H.323 and MGCP Approach

One topic is ‘HOT’ on the discussion forums now a days and that is how MGCP and H.323 gateway switchback to backup CUCM when primary is down or switchback to primary CUCM when it’s up again. I have tested some scenarios on my lab and the following procedures can be followed for such requirements:

For H323 GW

The command ‘h225 timeout tcp establish x’ plays the roll here within dial-peers. If any call agent goes down while in a call, after configurable number of seconds if searches other dial-peers with the same destination-pattern configured and switchback to that dial-peer.
!
voice class h323 1
h225 timeout tcp establish 3
!
dial-peer voice 1 voip
destination-pattern 3…
voice-class h323 1
session target ipv4:SUB
no vad
!
!
dial-peer voice 2 voip
destination-pattern 3…
voice-class h323 1
session target ipv4:PUB
no vad
preference 1
!

For MGCP GW

Either manually configure this on gateway (if we don’t download the configuration with the command ccm-manager config):
!
ccm-manager switchback immediate
!

Or configuring it on the MGCP GW page at CUCM (must need the command ccm-manager config):

“Switchback Timing* = Immediate”,  It’s ‘Graceful’ by default.

This is just to mention that: you can switchover to backup Call Agent manually with the command ‘ccm-manager switchover-to-backup’ if the command ‘ccm-manager switchover immediate/graceful/scheduled’ is already not configured.

happy labbing! 🙂