BLUF: I need some assistance on an EEM script. Script will reside on a switch and simply needs to shut down a loopback interface when a port goes down.
Background: I have a 16-port EtherSwitch module in a 4331 Router, with several mirrored systems with A/B routers plugged into the EtherSwitch. On the router, I have VRF with vasi interfaces working properly, and NAT, and everything is working great from the perspective of the router. Except, when router A on EtherSwitch port 0/1/3/5/7 goes down. When A goes down, the router should swap over to the B side, but because the A/B side is on the EtherSwitch module, the router never knows when it occurs because it cannot sense the interface going down in the switch module. Distant end router cannot respond to ping and I cannot make changes to that device, so i cannot IPSLA to the router itself. My proposition, use IPSLA on the router programmed with the primary route, and program the secondary, side B, with a higher AD. The IPSLA will watch the IP address of a loopback programmed on the switch module. From the switch module's perspective, the EEM script will monitor when route A goes down (is disconnected), and then send a shutdown command to the loopback. Thusly, port goes down due to distant router going down, EEM turns off the loopback, router senses the loopback not working, and routes to the second route. Just need help on the commands to get this working correctly as CCNA doesn't cover this. Thanks a bunch!