A distance-vector routing protocol determines least cost routes by modifying route distances reported by its neighbors. Unlike link-state protocols, distance-vector protocols do not attempt to model the entire network. Rather, distance-vector algorithms accept neighbor's routing tables as given and simply add on additional distance needed to reach the neighbor. For this reason, distance-vector processes are sometimes characterized as "routing by rumor."
The use of the word distance in distance-vector is open to various interpretations. For example, in Routing Information Protocol (RIP), distance is defined as hop count. By contrast, in Cisco's Enhanced Interior Gateway Routing Protocol (EIGRP), distance is a complex function including parameters of bandwidth, delay, reliability, and load. In general terms, distance refers to a routing metric, not to physical space.