Comparative Analysis and Route Optimization of State of the Art Routing Protocols

Performance of any network is based on the routing protocols. RIP, Session, OSPF and BGP are the few commonly used dynamic routing protocols used in today’s networks. Routing refers to the phenomenon of selecting the best available path to forward packets to its destination. It is a core feature for any network because the performance of the networks heavily depends upon it. In this paper we will perform comparative analysis by using Distance Vector, Link State and Session routing protocol. We will study Packet drop rate (PDR), Bandwidth / Link Utilization, End to End Delay, throughput behavior of these protocols by using network simulator 2 (ns2) for route optimization & comparative analysis to find optimal routing protocol


Introduction
Static routing has been failed to cop up with changing and growing dynamics of the network.There are several limitations and disadvantages of static routing as mentioned in [1].Dynamic routing has been proven to be fault tolerant, scalable, and secure and provide high network availability and throughput.Different dynamic routing algorithms have different preferences, limitations and requirements for their smooth operation and execution within the network.Therefore one of the challenges to study the behavior of these routing protocols was to design a network topology that provides equal opportunities for all routing protocols in a homogenous way.We try to configure network parameters like bandwidth, delay, buffer size etc. carefully in our network model so that network related parameters does not affect the effectiveness of one or other routing protocols in the simulation.The remainder of the paper is organized as follows: in section 2, dynamic routing protocols are reviewed.Section 3 describes the network model and its different configuration parameters in detail.Graphs and simulation results are discussed in section 4. Eventually, the conclusion of the study is given in section 5.

Literature review
Kindly Dynamic routing protocols have been proven as the founding building block of Internet [2].Routing refers to the phenomenon of forwarding packets on the basis of the destination address inside the packet header [3] routing nodes it will react to only when topology get change.Performance analysis of routing protocols [9] shown experimental results among EIGRP, OSPF in laboratory based testing.We in this paper perform simulation based analysis by using NS2 discrete event simulator to analyze the performance of the distance vector, link state and session routing protocols.

Brief overview of Dynamic Routing Protocols
A basic requirement of a communication network is to flow or route traffic from a source node to a destination node.Dynamic routing protocols play a pivotal role to achieve this goal.They construct routing tables by exchanging topology information by using several different algorithms.The most commonly used algorithms and techniques are Bellman Ford and Dijkstra all pairs.In this section we will discuss the most commonly used routing protocols like Distance Vector, Link State and Session protocols.

Distance Vector Routing Protocol
Distance is the cost of reaching a destination, usually based on the number of hosts the path passes through, or the total of all the administrative metrics assigned to the links in the path.From the standpoint of routing protocols, the vector is the interface traffic will be forwarded out in order to reach an given destination network along a route or path selected by the routing protocol as the best path to the destination network.Distance vector protocols use a distance calculation plus an outgoing network interface (a vector) to choose the best path to a destination network.The main disadvantages of the Bellman-Ford algorithm in this setting are as follows: •It does not scale well.
•Changes in network topology are not reflected quickly since updates are spread node-by node.
•Count to infinity if link or node failures render a node unreachable from some set of other nodes, those nodes may spend forever gradually increasing their estimates of the distance to it, and in the meantime there may be routing loops.

Link State Routing Protocol
Link

Session Routing Protocol
The static routing strategy described earlier only computes routes for the topology once in the course of a simulation.If the above static routing is used and the topology changes while the simulation is in progress, some sources and destinations may become temporarily unreachable from each other for a short time.Session routing strategy is almost identical to static routing, in that it runs the Dijkstra all-pairs SPF algorithm prior to the start of the simulation, using the adjacency matrix and link costs of the links in the topology.However, it will also run the same algorithm to recompute routes in the event that the topology changes during the course of a simulation.In other words, route recomputation and recovery is done instantaneously and there will not be transient routing outage as in static routing.
Session routing provides complete and instantaneous routing changes in the presence of topology dynamics.If the topology is always connected, there is end-to-end connectivity at all times during the course of the simulation.However, the user should note that the instantaneous route recomputation of session routing does not prevent temporary violations of causality, such as packet reordering, around the instant that the topology changes.

Network Model and Performance Evaluation based on Simulation
Displayed Refer to the Figure 1 to understand the network topology used for the simulation.We considered one hundred nodes or users connected to a switch and the switch is

Simulation Results
We used ns2 version 2.35 to perform the simulation.We used TCP protocol and FTP application to send packets towards the server, the course of the simulation was 100 seconds.We analyze the results on the basis of following four parameters. 1) Paket drop rate 2) Bandwidth / Link utilization 3) End to End delay 4) Throughput Packet Drop Rate for Distance Vector, Link State and Session Routing Protocol The comparison graph for distance vector, link state and session routing protocols for packet drop rate in figure 2 shows that session routing protocol has highest packet drop rate as compared to distance vector and link state routing protocol.Distance vector routing protocol has least drop rate as compared to LS and session routing protocols.
Bandwidth Utilization for Distance Vector, Link State and Session Routing Protocol.Figure 4 shows comparison graph for end to end delay all three routing protocols unlike distance vector routing protocol link state routing protocol end to end delay is much stable as compared to DV and Session routing protocols.

End to End Delay Comparison for DV, LS and Session Routing Protocols
Throughput Utilization for Distance Vector, Link State and Session Routing Protocol.

Conclusion
Simulation shows overall packet drop rate for Session routing protocol is higher than Link State and Distance Vector routing protocol, however we observe some instances where packet drop rate of distance vector routing protocol is higher than other two counterparts, average drop rate of Session and Link state routing Comparative Analysis and Route Optimization of State of the Art Routing Protocols protocol is almost same while distance vector has high average packet drop rates.We observe that distance vector routing protocol has better link utilization than Session and Link state routing protocol.Average Link utilization of distance vector routing protocol is better.
Session routing protocol has very high end to end delay as compared to distance vector and link state routing protocol.
Similarly, network throughput of distance vector routing protocol is better than link state and session routing protocol.We observed that Link state throughput was quite steady as compared to session routing protocols.

ALGORITHM 1 :
Distance Vector Algorithm (computed at node i) Initialized, () = 0; () = ∞ (   ℎ     ) For (nodes j that node i is aware of) do  () =      {() + ()} Eq. (I) Where D represents computed path cost from node A to node B and d represents direct link cost from node A to node B EAI Endorsed Transactions on Mobile Communications and Applications 01 2018 -03 2018 | Volume 3 | Issue 13 | e4

EAI
Endorsed Transactions on Mobile Communications and Applications 01 2018 -03 2018 | Volume 3 | Issue 13 | e4 connected to Internet cloud via Internet edge router.We planted 25 routers in the cloud connected in different arrangements see table 4 for the details.The server showing at right side of the fig. 1 is the ultimate destination of users' traffic.Routers used Distance Vector, Link State and Session routing protocols to select best bath to reach the server during steady state and under topology change situations.

Figure 1 :
Figure 1: users connected to internet to send data to the server See table 1 for the details of users' connectivity within the network.All one hundred users are connected to local area network switch via Ethernet link having bandwidth of 10 Mbps with 10ms delay, the switch is connected to edge router with 1Gbps bandwidth and 5ms delay.Table 2 and 3 explain the routers configuration parameters and interconnectivity details respectively.

Figure 3 :
Figure 3: Bandwidth Utilization for Distance Vector, Link State and Session Routing Protocol Figure 3 shows bandwidth comparison of all three routing protocols, apart from distance vector routing protocol which has unusual bandwidth

Figure 4 :
Figure 4: End to End Delay Comparison for DV, LS and Session Routing Protocols

Figure 5
Figure5shows throughput comparison of all three routing protocols, apart from distance vector routing protocol which has unusual throughput gain, link state and session routing protocol throughput is almost similar during half of the simulation time later on Link state throughput become much more stable.

Figure 5 :
Figure 5: Throughput Utilization for Distance Vector, Link State and Session Routing Protocol.

routing EAI Endorsed Transactions on Mobile Communications and Applications
. Routers speak different control languages (EAI Endorsed Transactions on Mobile Communications and Applications 01 2018 -03 2018 | Volume 3 | Issue 13 | e4protocols) to select the best route to forward the packets to avoid delays, loss and increase users' response time.
State protocols track the status and connection type of each link and produce a calculated metric based on these and other factors, including some set by the network administrator.Link state protocols know whether a link is up or down and how fast it is and calculate a cost to 'get there'.Since routers run routing protocols to figure out how to get to a destination, you can think of the 'link states' as being the status of the interfaces on the router.Link State protocols will take a path which has more hops, but that uses a faster medium over a path using a slower medium with fewer hops.Because of their awareness of media types and other factors, link state protocols require more processing power (more circuit logic in the case of ASICs) and memory.Distance vector algorithms being simpler require simpler hardware.
ALGORITHM 2: Dijkstra's Algorithm 1. Discover nodes in the network, N, and cost of link k-m, d i km(t), as known to node i at the time of computation, t. 2. Start with source node i in the permanent list of nodes considered, i.e., S = {i}; all the rest of the nodes are put in the tentative list labeled as S'.Initialize,   (  ) =   (  ) ,    ∈  ' Eq. (II) 3. Identify a neighboring node (intermediary) k not in the current list S with the minimum cost path from node i, i.e., find k ∈ S' such that D ik (t) = min m∈S' D im (t).Add k to the permanent list S, i.e., S = S ∪ {k}, Drop k from the tentative list S', i.e., S' = S'\{k}.  (  ) = min {  (  ) ,   (  ) +   ()} Go to Step 3.

Table 1 :
Table 2 and 3 explain the routers configuration parameters and interconnectivity details respectively.Connectivity details of users, switch and server

Table 2 :
Routers Configuration Parameter

Table 3 :
Routers interconnectivity detailsI.Simulating Links and nodes FailureDuring the course of the simulation we simulated different links and nodes failure the details the link and nodes failure are mentioned in table 4 and 5 respectively.