If the network connection to CUCM is down, if the E1 interface on MGCP voice gateway router would be down?

[cciejfliu]

Hi,

I have a question here.

We have two MGCP voice gateway routers configured on CUCM 7. If the network connection between the primary MGCP voice router and CUCM servers is broken, we notice that the status of the primary MGCP gateway on CUCM is unregistered, but the E1 internface (PSTN circuit) on that rouer is still up. This causes an issue that Telco carrier still sends incoming calls to PSTN link on the primary MGCP gateway router, not the backup MGCP gateway router which still registers with CUCM server. As a result, incoming calls just termiate on the primary MGCP router and cannot go anywhere.

I would like to know when primary MGCP gateway router loses connection to CUCM servers, if it is possible to for the MGCP router to bring down the E1 internface, which can let Telco carrier starts sending incoming calls to the backup MGCP gateway router.

Thanks

Bob

[Steven Holl]

The E1 won't go down unless L1 on the circuit goes down, which is independent of the network connectivity status to CUCM.

L2 on the circuit will go down when we lose connectivity to CUCM (assuming you don't have the SRST fallback configuration 'call app alternate default' configured).  A down L2 status should be enough of a status for the provider to hunt to another circuit, since that means there is no D-channel and no possible way to send a call to the router.

If you wanted to get fancy, you could use EEM to shut the controller down when L2 goes down, and run pings to CM until it's back up, and unshut the controller.

[cciejfliu]

Hi Steven,

Thank you for your reply. The problem is that when the our MGCP router lost connection to CUCM, we ran "show ISDN status" and noticed that the layer 2 and layer3 on the circuit are still up.

Regards

Bob

[Aaron Harrison]

Hi

Do you have 'ccm-manager fallback-mgcp' configured on this GW? That would switch the E1 over to terminate locally on the gateway for SRST purposes.

Aaron

Please rate helpful posts....

[Steven Holl · Accepted solution]

If L2 is still up, then that means the PRI is switching over it's D channel to terminate locally, like it does in SRST scenarios.

If you don't want this:

application
global
  no service alternate default

no ccm fallback-mgcp

Keep in mind that if you disable this feature, this gateway will never function properly as an PSTN gateway for calls out this circuit when in SRST.  If this gateway isn't an SRST router with call-manager-fallback configured, then you should have no worries.

[cciejfliu]

Hi Steven,

Your comments exactly answer my question. Thank you very much for your kind helps.

Regards

Bob