I needed to setup notification to be sent via email when a circuit went down and failed over to a backup circuit on a Cisco Router 2921. Here’s what I did.
Create IP SLA
I create my IP SLA to monitor ICMP of the internet…
router(config)#ip sla 1 router(config)#icmp-echo 188.8.131.52 source-interface GigabitEthernet0/0 router(config)#ip sla schedule 1 life forever start-time now
Note: Instead of specifying source-interface GigabitEthernet0/0, I could configure a route to use that interface’s gateway. In my setup, I have 2 WAN links, so I need to be specific at the least in which interface I’m monitoring.
Create Track Object
Now that the IP SLA is set up, I can set up a track object to monitor up/down state of IP SLA
router(config)#track 1 ip sla 1 reachability router(config)#delay down 5 up 10
This means that if the remote IP (184.108.40.206) is unreachable for 5 seconds, it is down. If it comes back up and is reachable for 10 seconds, it is considered up.
With both of these in place, now I can create my event monitor applet.
Create Event Monitor Applet
I define a few variables to make life easier when writing future applets.
router(config)#event manager environment _email_server 192.168.1.10 router(config)#event manager environment _email_from email@example.com router(config)#event manager environment _email_to firstname.lastname@example.org
This sets up 3 variables I can use later in my action stanzas by simply referencing
Now, I configure the applet.
router(config)#event manager applet internet_down router(config-applet)#event track 1 state down router(config-applet)#action 1.0 syslog msg Primary Internet Circuit Down router(config-applet)#action 1.1 mail server $_email_server to $_email_to from $_email_from subject Circuit Down body Primary Internet Circuit Down.
That’s all there is to it. You could add another applet, say, internet_up to track 1 state up and send a different message when circuit comes back up. I do have a second applet to notify of circuit up since I have 2 WAN links I monitor on a single router and both WAN links failover to each other to provide reliability for the multiple VLANs on the network that require high availability.