Our ISP have setup HSRP on their switch, x.x.x.1/24 and I've set up HSRP x.x.x.11/24 on the external interfaces of our two routers, rtr1 and rtr2. I have rtr1 set with higher priority and have preempt enabled.
It's working except for 1 of 5 failure scenarios I tested. When I unplug the external interface on rtr1, rtr2 external becomes active but no traffic is getting past our router. I can ping our HSRP but not the ISP.
The other 4 scenarios are:
* Unplug internal of rtr2 (nothing happens as expected).
* Unplug internal of rtr1. Internal of rtr2 become active and traffic gets out to Internet. I replug internal rtr1 and rtr1 becomes active again, as expected.
* Unplug external of rtr2 (nothing happens as expected).
* Unplug both external and internal of rtr1 (to simulate rtr1 router failure) and external and internal of rtr2 become active and traffic passes as expected.
I've created a ticket with Cisco and an engineer confirmed my HSRP config. I guess my real question is, is it possible that the ISP did not configure something correctly? I want to see if this is plausible before contacting them.