Routers that use distance-vector protocol determine the distance between themselves and a destination. The best route for Internet Protocol packets that carry data across a data network is measured in terms of the numbers of routers (hops) a packet has to pass to reach its destination network. Additionally some distance-vector protocols take into account other traffic information, such as network latency. To establish the best route, routers regularly exchange information with neighbouring routers, usually their routing table, hop count for a destination network and possibly other traffic related information. Routers that implement distance-vector protocol rely purely on the information provided to them by other routers, and do not assess the network topology.