Interface Tracking with FHRP's

[Roberto Kippins]

Hi I am trying to configure interface tracking with any fhrp  eg hsrp  thing is if you have a router connected to a device like a dsl modem line protocol will still show up on the router eventhough you cant get out to the internet, what can i do to detect an issue liek that and set the router to lower its priority so the redundant router can take over ? i can configure track objects and set it in hsrp but what specifically can i do for a situation above.

Thanks.

[wpalumbo06 · Accepted solution]

Been awhile since I have done this but I believe it goes something like this:

interface FastEthernet0/0

ip address 10.10.10.2 255.255.255.0

shutdown

duplex auto

speed auto

standby 1 ip 10.10.10.1

standby 1 priority 150

standby 1 preempt

standby 1 track 300 decrement 75

track 300 rtr 1 reachability

ip sla 1

icmp-echo 8.8.8.8

ip sla schedule 1 life forever start-time now

This will cause the HSRP active router to check the reachability of the Internet address 8.8.8.8 and if it becomes unreachable, HSRP will decrement the priority by 75, causing the standby router to become active assuming it's priority is 100.  Also need to make sure the standby router is configured to preempt so that it can take the active role when it sees the active router's priority as 75 after it is decremented.

[Roberto Kippins]

thanks bro ill try this now and see what happens

[Roberto Kippins]

So i didi this in gns3 where i created a bunch of routes with eigrp and setup a router with 8.8.8.8  and at the othe rend i setup two routers with hsrp and configured the tracking and it did work but i noticed the transitioning from one router to the other took about 30 seconds i was wonderinf if it had to do with my timer configs on the hsrp routers because i did set the hold off timers to 20 seconds

[wpalumbo06]

You can experiment with the HSRP timers (try 1/3 instead of 3/10) but I wouldn't recommend getting too aggressive as you are essentially relying on Internet reliability to change your topology and that can be problematic if there are Internet issues.  I used 8.8.8.8 for simplicity but it would probably be better to use and IP address of your ISP (assuming they permit ICMP) as this will reduce the likelihood of issues should there be an Internet problem somewhere out in the 'cloud'  Additionally, you can do similar things with static routes and IP SLA - just Google it and you'll find plenty of examples....have fun!