Distance Vector Protocols

Distance vector protocols were invented before link state protocols.

Early examples are RIPv1 and Cisco's proprietary protocol IGRP (which was updated to EIGRP).

Distance vector protocols operate by sending the following to their directly connected neighbors.

• their known destination networks.

• their metric to reach their known destination networks.

This method of sharing route information is often called 'routing by rumor'. This is because the router doesn't know about the network beyond its neighbors. It only knows the information that its neighbors tell it.

Called 'distance vector' because the routers only learn the 'distance' (metric) and 'vector' (direction, the next-hop router) of each route.