Routing Protocols

Routing Protocols Explained
By Brian Wilson

Preface:

In this paper I will explain many different routing protocols and give some basic details and features about them. This paper in no way should be considered a source of full detail about any of the listed protocols. For detailed information about routing protocols I would suggest looking into the Request For Comments (RFC) for that protocol, goggling them, or maybe visiting different vendor’s websites such as Cisco, Juniper, or Bay networks. Most vendors’ web sites have detailed explanations about all the Protocols there equipments support features. Before you can understand routing protocol you will have to have a basic understanding or IP networks, Variable Length Subnet Masks (VLSM), Network Topologies (bus, star, Hub, ect..), and the OSI model. If you are not familiar with any of the above subjects you may want to read up and learn about them before moving into routing protocols. Routing protocols are what makes the internet work by moving traffic from network to network. With out routing protocols the internet could not work because networks would just be separate LANs with no connection to others LANs. The internet in basic terms is just a lot of LANs wired together to make a huge WAN.

Protocol types:

Distance Vector: distance vector routing is a type of routing protocol that discovers routes on interconnected networks. The Distance Vector routing algorithm is the based on the Bellman-Ford algorithm. Examples of distance-vector routing protocols include RIP (Routing Information Protocol), Cisco's IGRP (Internet Gateway Routing Protocol) try Google to see all the different protocols in the Distance Vector family. Distance Vector protocols are suitable for smaller networks as many of the protocols in this family aren't scaleable in lager complex networks as they are limited. The main limit to Distance Vector Protocols is there method that requires each router simply inform its neighbors of its routing table. This routing table update to other members is bandwidth intensive to lager networks.

RIP (Routing Information Protocol):

Routing Information Protocol (RIP) is one of the first protocols to be used in networking and is classified as a distance vector routing protocol. RIP uses broadcast User Datagram Protocol (UDP) data packets to exchange routing information. There are two versions RIP V1 & V2. RIP Version 1 is the original version and has many limitations. The metric that RIP uses to rate the value of different routes is hop count. The hop count metric works by assigning static routes with a value of 0 and all other routers values are set by the number of hops (up to 15) that the data must travel though to get to an end point. RIP Version 2 supports plain text and MD5 authentication, route summarization, classless inter-domain routing (CIDR), variable-length subnet masks (VLSMs), Multicast support. Some vendors support other non-standard features for RIP but be careful as many vendor centric features are not compatible in a mixed vendor network.