Note: Many topics at this site are reduced versions of the text in "The Encyclopedia of Networking and Telecommunications." Search results will not be as extensive as a search of the book's CD-ROM.

The distance-vector routing is a type of algorithm used by routing protocols to discover routes on an interconnected network. The primary distance-vector routing algorithm is the Bellman-Ford algorithm. Another type of routing algorithm is the link-state approach. Routing protocols that use distance-vector routing include RIP (Routing Information Protocol), Cisco's IGRP (Internet Gateway Routing Protocol), and Apple's RTMP (Routing Table Maintenance Protocol). The most common link-state routing protocol is OSPF (Open Shortest Path First).

Dynamic routing, as opposed to static (manually entered) routing, requires routing algorithms. Dynamic routing protocols assist in the automatic creation of routing tables. Network topologies are subject to change at any time. A link may fail unexpectedly, or a new link may be added. A dynamic routing protocol must discover these changes, automatically adjust its routing tables, and inform other routers of the changes. The process of rebuilding the routing tables based on new information is called convergence.

Distance-vector routing refers to a method for exchanging route information. A router will advertise a route as a vector of direction and distance. Direction refers to a port that leads to the next router along the path to the destination, and distance is a metric that indicates the number of hops to the destination, although it may also be an arbitrary value that gives one route precedence over another. Internetwork routers exchange this vector information and build route lookup tables from it.