ROUTING PROTOCOLS

Types of routing protocols

1. Distance vector (RIP, IGRP)
2. Link state (OSPF, IS-IS)

Cisco has created its own routing protocol – EIGRP. EIGRP is considered to be a complicated distance vector protocol, though some materials erroneously state that EIGRP is a hybrid routing protocol, a mixture of distance vector and link state.

All of the routing protocols mentioned above are interior routing protocols (IGP), which means that they're used to exchange routing information inside one autonomous system. BGP (Border gateway Protocol) is AN example of AN exterior routing protocol (EGP) which is employed to exchange routing info between autonomous systems on the web.

Distance vector protocols

As the name implies, distance vector routing protocols use distance to work out the most effective path to a remote network. the gap is sometimes the quantity of hops (routers) to the destination network.

Distance vector protocols send complete routing table to every neighbor (a neighbor is directly connected router that runs the same routing protocol). they typically use some version of Bellman-Ford rule to calculate the most effective routes. Compared with link state routing protocols, distance vector protocols are easier to set up and need very little management, however are at risk of routing loops and converge slower than link state routing protocols. Distance vector protocols also use a lot of bandwidth as a result of they send complete routing table, whereas link state procotols sends specific updates only topology changes occur.

RIP and EIGRP are examples of distance vector routing protocols.

Link state protocols

Link state routing protocols are the second variety of routing protocols. they need the same basic purpose as distance vector protocols, to search out a best path to a destination, but use completely different ways to do so. not like distance vector protocols, link state protocols don’t advertise the complete routing table. Instead, they advertise information a few network toplogy (directly connected links, neighboring routers…), in order that within the finish all routers running a link state protocol have the same topology database. Link state routing protocols converge much quicker than distance vector routing protocols, support classless routing, send updates using multicast addresses and use triggered routing updates. They additionally need a lot of router mainframe and memory usage than distance-vector routing protocols and may be tougher to set up.
Each router running a link state routing protocol creates three completely different tables:

1. neighbor table – the table of neighboring routers running the same link state routing protocol
2. topology table – the table that stores the topology of the complete network
3. routing table – the table that stores the most effective routes