COMPARATIVE ANALYSIS OF CONVERGENCE TIMES BETWEEN OSPF, EIGRP, IS-IS AND BGP ROUTING PROTOCOLS IN A NETWORK Eunice Domfeh Asabere 1 , Joseph Kobina Panford 2 , James Ben Hayfron-Acquah 3 1 Final Year M Sc. I.T, Dept. Of Computer Science, KNUST, Kumasi, Ghana, easabere@ssnit.org.gh 2 Dept. Of Computer Science, KNUST, Kumasi, Ghana, jpanford@yahoo.com 3 Dept. Of Computer Science, KNUST, Kumasi, Ghana, jbha@yahoo.com ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - Convergence time is a key factor in determining performance of routing protocols and routing protocol is one of the significant factor in determining the quality of IP communication. Convergence time is therefore very essential to a network and networks that converge faster are considered to be very reliable. The research was carried out to compare the convergence of four routing protocols namely OSPF, EIGRP, IS-IS and BGP. Network scenarios were created and a simulation was performed using Graphic Network Simulator (GNS3) to measure the convergence times of the protocols separately. Results indicated that EIGRP had the fastest convergence time in both link failure and topology change scenarios. This will help network administrators in their choice of protocols. Key Words: Convergence time, Protocol, Network, Routing, OSPF, BGP, IS-IS, EIGRP 1. INTRODUCTION 1.1 Background of Study Data packets traveling through the network typically traverse multiple routers and thus multiple physical links interconnecting them. Whenever there is a link failure or change in topology, routing protocols try to provide an alternative path towards the destination. It is therefore crucial that the routing protocol quickly detects such a link failure or topology change. With the increasing use of networks, any unnecessary loss of connectivity can hardly be tolerated and has to be kept as short as possible. This brings up the issue of convergence time and network is believed to have converged when the routing tables on all routers within the network are complete and correct. Routing protocols play a major role in the delivery of packets from source to destination addresses. In the study, four routing protocols namely Open Shortest Path First (OSPF), Border Gateway Protocol (BGP), Intermediate system to Intermediate system (IS-IS) and Enhanced Interior Gateway Routing Protocol (EIGRP) were compared to determine their convergence time in a given network topology. 1.2 Statement of the Problem One of the most important characteristics of routing protocols is the convergence time The convergence time determines how fast the routers adapt their routing tables to topological changes. Among OSPF, EIGRP, IS-IS and BGP, a proof-based advice for selecting the one with the best convergence time is aimed at. 1.3 Research Objectives The main objectives of this research are: • To determine the convergence time for OSPF, BGP, IS-IS and EIGRP in a particular network topology. • To compare the performance of OSPF, BGP, IS-IS and EIGRP. 1.4 Research Questions The following are the research questions that were posed in order to accomplish the objectives. • What is the convergence time for OSPF, BGP, IS-IS and EIGRP in a network Topologies? • Which of the four routing protocols has the fastest convergence time in the topology used. 1.5 Significance of the Study This study will be significant in providing an in depth understanding of the four routing protocols OSPF, BGP, IS-IS and EIGRP and determining the convergence time of these protocols in a network. The study will also compare the convergence times of these routing protocols and come out with the best one. 2. LITERATURE REVIEW Convergence can be defined in many ways but in the context of computer networks, a network is said to have converged when all routers in a network have the same topological information about their network they find their selves in. With the help of routing protocols, routers collect topological information [1]. Convergence is a critical property in routing especially dynamic routing. There are about three forms of routing namely static, default and dynamic [2]. A network topology is said to have converged Dzwhen routing tables on all routers within the network are complete and correctdz [3]. Convergence addresses the manner in which networks recover from problems and network changes. Modern networks anticipate problems by providing alternate, redundant or standby paths. Convergence time is the time that is required for the routers in a network to learn about routes in a given network. This time is important because it helps administrators of a network to determine in the event that a network downtime occurs due to a failed link between routers or any damage to one router the amount of time it will take for that network to recover and begin to function as a normal network. Deng et al. [4] performed analysis of RIP and OSPF and EIGRP using OPNET which is a simulator widely used for networking related analysis. In their research, they analysed the performance of these protocols based on their convergence activity, convergence duration and traffic sent International Journal of Computer Science and Information Security (IJCSIS), Vol. 15, No. 12, December 2017 225 https://sites.google.com/site/ijcsis/ ISSN 1947-5500