Distance Vector Loop Prevention Mechanisms


1. RIP has a maximum allowed distance of 16 hops after which the route is considered invalid.  Therefore RIP can really be only used on small networks.
2. Route poisoning by setting the maximum distance to 16 hops for routes which are not valid anymore
3. Triggered Updates (opposed to normal 30 second RIP updates) as soon as there is a change which affects the routing table
4. Split Horizon is a mechanism to ensure that a routing update is not sent in the same direction from which it was originally received
5. Hold down timers ensure that the routing updates are only accepted once a set amount of time has elapsed (default 180 seconds) to prevent incorrect routing updates due to a ‘flapping’ interface (ex. bad network card) and triggered updates taking place
http://www.uoverip.com/distance-vector-loop-prevention-mechanisms/