IMPACT OF NETWORK SCALABILITY ON THE PERFORMANCE OF RIP AND IGRP FOR EMAIL SERVICES

Dynamic routing is one of the major areas in computer networks, in which routing protocols are used to automate the process of routing. Routing protocols dynamically determine best path(s) to every network. Routing protocols are classifed as distance vector and link-state routing protocols. Routing Information Protocol (RIP) and Interior Gateway Routing Protocol (IGRP) are examples of distance vector while Open Shortest Path First (OSPF) and Intermediate System to Intermediate System (IS-IS) are link-state routing protocols. Both RIP and IGRP are using different metrics to evaluate best route to a destination in the network. RIP uses a simple metric value of hop-count while IGRP uses a composite metric. A composite metric consists of several attributes like bandwidth, delay, reliability, Maximum Transmission Unit (MTU) and load. Usually it is considered that because of the simple metric value, RIP produces better results for any application in simple network architectures. This paper studies the performance of RIP and IGRP in simple networks of different sizes, using email application as evaluation entity. The objective is to fnd that where, in simple network architectures, RIP with its simple metric will produce better email services or IGRP will win the race with the help of its composite metric. This study also investigates the effect of scalability on both of the routing protocols when the size of the network grows. The behavioural study of RIP and IGRP for email, in different sizes of networks, will also help in evaluating the behaviour of simple and composite metrics. Simulations and experiments results indicate that IGRP produces better results for email services as the size of the network becomes more scalable and the number of hops between source and destination increases, even if simple network architecture is followed. The results also indicate that IGRP consumes relatively less CPU pulses of email server.