(split h&-rī´z&n) (n.) A routing technique that eliminates the chance of a routing scheme creating routing loops, effectively making routing more efficient. When a router in a network with only one data path receives a data packet, it does not send routing information back along the path on which the packet traveled (i.e., to an adjacent router); it only sends the information forward so that there is no possibility of the packet being routed back along the path it originally traveled.
Routing Information Protocol General information for understanding the Routing Information Protocol and how split horizon works in that scheme. (pdf)
Unicast IP Routing Microsoft explains how modifications to routing algorithms can reduce convergence problems in networks.