[c-nsp] EIGRP, variance and offset-list out

Dmitry Sergienko dmitry.sergienko at gmail.com
Thu Dec 22 18:05:29 EST 2011


Thanks Andriy,

that's exactly what I was missing - required condition to be a
feasible successor:

"Note: If a path is not a feasible successor, the path is not used in
load balancing. Refer to the Feasible Distance, Reported Distance, and
Feasible Successor section of Enhanced Interior Gateway Routing
Protocol for more information."


"Setting a variance value lets the Cisco IOS software determine the
feasibility of a potential route. A route is feasible if the next
router in the path is closer to the destination than the current
router and if the metric for the entire path is within the variance.
Only paths that are feasible can be used for load balancing and
included in the routing table.

If the following two conditions are met, the route is deemed feasible
and can be added to the routing table:

•The local best metric must be greater than the metric learned from
the next router.

•The multiplier times the local best metric for the destination must
be greater than or equal to the metric through the next router."

Well, in this case I need to find another solution how to influence
EIGRP metrics to achieve proper unequal cost load balancing and
metrics management only from R2 router.

Thanks a lot for help!

2011/12/22 Andriy Bilous <andriy.bilous at gmail.com>
> Notice that Advertised Distance (768) over Tunnel2 is now > Feasible
> Distance (512) of the best route and as such this route can't be a
> feasible successor, can't be considered as an alternative path and
> therefore can't be installed in routing table. So, as long as
> offset-list adds <=255, advertised distance is < FD=512 and both
> routes are installed.


Best wishes,
Dmitry Sergienko

More information about the cisco-nsp mailing list