I have a voice gateway 3845 hosting a PRI on it, backhauled to a CUCM cluster using MGCP.
There is no SRST feature enabled on the gateway nor H323 configuration (no fallback mode).
Because I want to be sure to not receive incoming calls from telco when the backhauling is lost, I added the command:
This command forces the shutdown of the ISDN layer2 when the MGCP connection is lost with a CUCM.
I would like to know which behavior will occur in this scenario:
1- outgoing call active from an IPPhone through the gateway and PRI
2- first CUCM connection is lost (CUCM down) --> GW fails over to second MGCP host
3- second CUCM's MGCP connection becomes active
What about call preservation in this case? Does my call remain active during this failover? Even with the "shut-backhaul-interfaces" command?
4- first CUCM becomes active, gateway registers to CUCM back --> switchover
In fact, I am pretty sure the connection would remain active without the command "shut-backhaul-interfaces". Normally, MGCP call preservation is supported with PRI when there is no fallback configured on the router.
My question is: which impact the command "shut backhaul" to this?
Thank you for your help.
AFAIK, MGCP call preservation will only work when the gateway failovers to another CUCM node. It does not work when failing over to SRST. That command, ccm-manager shut-backhaul-interfaces, will disable the circuit on the interface level. Any call on that PRI will get dropped when layer 2 goes down. That should not happen when failing over between CUCMs, only when there are no CUCMs to failover and the bakhaul socket is torn down.