When it
comes to the different types of routing protocols, the simplest and easiest one
of them is Distance vector routing protocols.
Confused why it is the simplest and easiest one? It is because that
Distance Vector Routing Protocols uses bellman ford algorithm.
The approach
used by distance vector routing protocols is also known as routing by rumor.
This is because that all those routers that use distance vector routing
protocols, instead of possessing the topological information about the network,
they rely on the neighbors information. Such routers, periodically update their
neighbors about the network changes using limited broadcast with the
destination IP address 255.255.255.255.
The term
“Distance Vector” comes from the fact that distance vector routing protocols
use the distance, as a metric, and direction, as a next-hop, for the best path
selections.
In all
directions, Distance Vector algorithms send updates to their near neighbors If
the routing table is updated in any way. At each exchange, the router adds its
own distance value to the distance value received for a route. The router that
got the update sends the revised table forth again, and the procedure is
repeated by receiving routers.
Every router
using the distance vector routing protocol will rely on the information of its
neighbors, even if that information isn't always accurate. Due to the
possibility of routing loops arising as a result of this phenomenon, extra loop
avoidance mechanisms have been added to distance vector routing protocols.
The routers
using Distance Vector routing protocols do not verify if anyone is listening to
the updates they send, however they broadcast the updates on a regular basis
even if the network topology remains unchanged.
Some
examples of Distance Vector routing protocols (that definitely uses distance
vector routing algorithm) are Routing Information Protocol (RIP) and Interior
Gateway Routing Protocol (IGRP). The routing information protocol (RIP) which
comes in two versions RIPv1 and RIPv2 is an open standard, while Interior Gate
Routing Protocol (IGRP) is a Cisco proprietary protocol. Cisco Introduced
Enhanced Interior Gateway Routing Protocol as an enhancement to IGRP. EIGRP was
formerly a Cisco proprietary protocol, but in 2013, Cisco declared it an open
standard protocol that may be used on any business equipment.