[c-nsp] HSRP and routing asymmetry

[Asbjorn Hojmark - Lists]

> To keep things simple, let's assume that I'm using 10.1.1.0/24
> and 10.1.2.0/24 as data-centre prefixes, agg1 is the HSRP
> active router for 10.1.1.254, and the HSRP standby router for
> 10.1.2.254, and agg2 is the HSRP standby router for 10.1.1.254,
> and the HSRP active router for 10.1.2.254.

You could announce each /24 as two /25s on the primary agg, say
10.1.1.0/25 and 10.1.1.128/25, plus 10.1.1.0/24. Because of
longest match routing, traffic would always flow via the active
agg.

Actually, even the secondary agg could use the longest match
route and send traffic via the primary, even though it has a
directly connected interface. (Longest match is used before the
admin distance).

-A
PS: But, honestly, just ignore the asymmetry.