Sunday, January 18, 2009

HSRP - Tracking


In my experience it would be useful to track an end to end connection, rather than the local serial connection (which may not go down when e2e connectivity is lost).

In the above diagram R1 should be the active HSRP router as long as it maintains its frame relay connection to R3. The trouble here is that the serial connection on R1 will remain 'up' even if the serial connection on R3 goes down.

One way around this is to configure a tunnel connection between R1 and R3 and run IP keepalives over this. Then with the HSRP configuration track the status of the tunnel connection. In this instance the tunnel connection goes down when the end to end connection over the frame relay cloud goes down.

R3
int tu0
ip unnumber lo0
tunnel source 149.1.123.3
tunnel dest 148.1.123.1
keepalives 10 3


R1
int tu0
ip unnumber lo0
tunnel source 149.1.123.1
tunnel dest 148.1.123.3
keepalives 10 3


int fa0/0
standby ip 149.1.127.254
standby priority 110
standby preempt
standby track tu0 11


R2
int fa0/0
standby ip 149.1.127.254
standby priority 100
standby preempt

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