Editing Routing (section)

===Distance vector algorithms===
{{main|Distance-vector routing protocol}}
Distance vector algorithms use the [[Bellman–Ford algorithm]]. This approach assigns a ''cost'' number to each of the links between each node in the network. Nodes send information from point A to point B via the path that results in the lowest ''total cost'' (i.e. the sum of the costs of the links between the nodes used).

When a node first starts, it only knows of its immediate neighbors and the direct cost involved in reaching them. (This information — the list of destinations, the total cost to each, and the ''next hop'' to send data to get there — makes up the routing table, or ''distance table''.) Each node, on a regular basis, sends to each neighbor node its own current assessment of the total cost to get to all the destinations it knows of. The neighboring nodes examine this information and compare it to what they already know; anything that represents an improvement on what they already have, they insert in their own table. Over time, all the nodes in the network discover the best next hop and total cost for all destinations.

When a network node goes down, any nodes that used it as their next hop discard the entry and convey the updated routing information to all adjacent nodes, which in turn repeat the process. Eventually, all the nodes in the network receive the updates and discover new paths to all the destinations that do not involve the down node.