EIGRP-Split Horizon

Lessons Learned:

EIGRP – Split-Horizon (distance vector Behavior)

Always on

-Undesired in partial mesh NBMA

Disabled at the interface Level
-#No ip split-horizon eigrp (as #)

Wont cause a loop due to DUAL feasibiltiy condition.

In EIGRP split horizon is not used as a loop prevention – it’s more actually usded to maek the updateing process more effiecient.

Once case where you’d want to diable Split-horizon would be on an NBMA netowrk or a network running in a Hub and Spoke. Where the extenal interface that all the Hubs connect to – we would need to disable Split-horizon so that the updates from Spoke #1 wouldb be abble to go back out the same interface towards Spoke2, Spoke3, and so-on.

Note: Unlike RIP where RIP enables Split-Horizon on the main interface over Frame-relay, EIGRP will use spit-horizon on every single interface.

Note: The EIGRP DUAL algorithm is what will prevent Loops in the topology based on the feasibly condition. In EIGRP Split-horizon is used more for a better path selection that loop avoidance.

EIGRP Will only advertise what is in the routing table.