RIPf anti-loop mechanism
Split horizon
Routes learned from an interface are not broadcast back to the interface. Cisco can disable split horizon for each interface. This feature is very useful in (NBMA) non-broadcast multi-channel access to hub-and-spoke environment.
Poison reverse
The route learned from an interface is sent back to the interface, but the route is poisoned. The hop count is set to 16 hops, which is unreachable.
Trigger update
Once detecting a route crash, the router immediately broadcasts a route update packet without waiting for the next refresh interval.
Suppression timer
This prevents frequent routing table changes and improves network stability.
