[c-nsp] HSRP, and the router on the other side...

[Andy Koch]

On Mon, Mar 29, 2010 at 16:47, Phil Mayers <p.mayers at imperial.ac.uk> wrote:
> You don't. You can't. It's (arguably) a weakness of HSRP compared to some
> combined layer2/layer3 failover protocols e.g. Extreme ESRP.
>
> The return traffic will always come in via the lowest-cost route, and if it
> hits the HSRP standby, it will be emitted there, since a "connected" route
> always wins.
>
> Depending on what routing protocol you are using you could write an EEM
> applet to modify a route-map changing the advertised route metric when HSRP
> master/slave status changes, but honestly I wouldn't bother - instead, just
> deal with the issue.

If you are going to force all the traffic one way, why make it hard on
yourself with EEM.  Set a priority on the HSRP group and allow preempt
so you know which is to be the active router (unless it fails), then
cost accordingly on your choice of dynamic routing protocols.

So, if you prefer to go to R1

On R1:
int ethernet
ip address 10.10.10.2
standby 1 ip 10.10.10.1
standby 1 preempt
standby 1 200
<insert command for lower cost, higher preference for your dynamic
routing protocol>


On R2:
int ethernet
ip address 10.10.10.3
standby 1 ip 10.10.10.1
standby 1 preempt
standby 1 priority 100
<insert command for higher cost, lower preference for your dynamic
routing protocol>

Andy
gawul00+cnsp at gmail.com