Poison reverse is a method used in RIP.When path information become invalid,routers will not immediately remove them form the routing table,but use a hop-count of 16,which is an inaccessible metric value and broadcast it out.
This increase size of routing table but is helpful in eliminating loops.It can immediately remove any loop between adjacent routers.The purpose of route poisoning is to avoid problems caused by inconsistent updates and to prevent network loops
split-horizon is a method of preventing routing loops in distance-vector routing protocols by prohibiting a router from advertising a route back onto the interface from which it was learned. Thus when a device that participates in such route advertisements receives an update from an interface, it (the device) does not forward updates through the same interface out. By doing so, routing loops are prevented.
What is Poison Reverse and split-horizon?
by Shabeer ibm