Comparative Analysis Of Eigrp And Ospf Routing Information Technology Essay

In this running era of technology, the technology of communication is increasing day by day. The communication networks plays important role to send any information like file or printer sharing, video streaming and voice conferencing etc and these days internet is the best medium to share information remotely and allow people to communicate, collaborate and interact with each other. All this information is managed by communication networks in which Routing Protocols are used to transfer information or packets across internet. The Open System Interconnection (OSI) reference model by International Organization for Standardization (ISO) created Routing Protocols by which network is control and able to communicate with each other around world. The main job of Router is to provide best path to packet from source to destination by using various metrics values leading to many different properties of path and then calculated the best path for packet to reach destination in network.

The numbers of Routing Protocols are available to manage the network or to connect multiple networks. Internet Protocol (IP) is the most commonly known protocol among all of them and In this thesis two most widely used protocols of intra Domain Routing Protocols will be analysed, which are Enhanced Interior Gateway Routing Protocol (EIGRP) and Open Shortest Path First (OSPF) Routing Protocol where as EIGRP is a Cisco proprietary Interior Gateway routing protocol via Distance Vector Protocols and OSPF routing protocol is Link-State Interior Gateway Routing protocol and also consider important protocol for real time applications.

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Aims and Objectives

All routing protocols have different performance in the network so its important to choose the right one for your network and this selection can be done on the basis of network scalibilty, convergence time and bandwidth requirements. In this Project EIGRP and OSPF Routing Protocols are chosen and the comparitive anaysis of these two protocols in real-time trafic will be take place in different senario and evaluating which protocol will give best route real-time trafic. Further in this project, different routing protocols will be discuss as their features and properties and theoritical and simulation analyse will be done with quantative metrics.

The Cisco Proprietary EIGRP is based on Diffusing Update Algorithm (DUAL) and its cost is calculated on the basis of delay and bandwidth [3] . on other hand OSPF routing protocol work on the bases of DIJKSTRA ALGORITHM or Shortest Path First (SPF) and the calculation of its cost is based on bandwidth [4]. These protocols uses different algorithm to route the trafic and this can be vary in convergence time and route proccessing delay according to their calculation so this can effect the network performance. To find out which protocol have better performance in large or small network, three different network models will be designed by EIGRP and OSPF routing protocols repectively by network simulator.

1.2 Project Methodology

In this project two routing protocols EIGRP and OSPF will be analyse in by three methods:-

A network model will be designed with EIGRP and simulation will be done in Cisco Packet Tracer and results will be observed.

On the same designed network, OSPF will be impliment and performance will be recorded.

And in the last same designed network will be impliment by both OSPF and EIGRP routing protocols to simulate the performance of real-time trafic.

Routing Protocols Background

Routing Protocols in IP networks are important to transfer data or any packet on time and responsible for sending packets to correct destination address and also these Routing Protocols are intelligent enough to select right information from relevant source and forwarding to destination node via one-hop or multi hop. Routing Protocols in router creates routing table by collecting information from the neighbour router which helps router to calculate the best path to forward the packet. All routing protocols are usually works on layer 3 (network layer).

There are many classifications of Routing Protocols for example Static routing, dynamic routing and Link-State routing protocols further classes distance vector routing protocols, RIP, VSLM and CIDR, EIGRP and OSPF. Also these protocols help to build other network communication protocols for example wireless ad-hoc networks and mesh wireless networks and many other.

The network in Internet is highly dynamic that is why its protocols are equally dynamic, among all Routing Protocols EIGRP and OSPF are two widely used protocols and both comes under dynamic routing protocols, in which EIGRP is based on Interior Gateway Routing Protocols and also EIGRP contains new features by which the market potential is expanded. OSPF is also Interior Gateway Routing protocol and works on Link-state and (SPF) Shortest Path First technology. Thanks to these routing protocol technology which increases and helped in improving the communication in such a perfect and correct way around the world.

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Overall Routing

There are many routing protocols by which routers in different networks are able to communicate with each other with different properties. The following properties will provide overall view of Routing, what properties do router use and why.

Desirable Properties of Routing

Loop:

While providing route for packet to reach destination, routing protocol are responsible to provide loop free route in network which results as low bandwidth used during process and can be used efficiently.

Demand Based Operation:

The demand based operation means that protocol should provide only the information when requested by node which helps to save the valuable resources used in network.

Convergence:

Convergence is basically occurrence of two or more things coming together, when ever link changes router automatically notice the change and process the update by calculating the new route and also forward the updated table. Convergence is totally depends on the routing protocols if convergence occurs in network it can result in bad route calculation or may drop the packet or time out. So the routing protocol should converge as fast as possible.

Security:

All protocols used in routing must ensure that the packets are transmitted with security to chosen destination.

Multiple Routes:

Routing protocols are responsible to provide multiple routes for the packets to reach its destination from its routing table when selected link by the routers fails or if there is any congestion on a particular route, this takes time to discover new route but by some selected routing protocols it is possible for router to do this job in seconds.

Quality of Service:

All Protocols doesn’t support Quality of Service as fact there is no widely deployed QOS aware Routing Protocols. But some protocols do support the Quality of Service depending upon their intended network use, like in EIGRP bandwidth and delay are consider with static parameters and in OSPF only bandwidth is consider with static parameters.

2.2 Routing and Metrics

2.2.1 Metrics and its Purpose

The cost of path in routing is based on the metrics parameters by metrics it is possible to compare or measure the path and all routing protocols select lowest metrics value among all values to determine the best path for routers. All Routing Protocols have their own metric calculation to decide the best bath.

At a stage where routing protocol learn multiple path to reach remote networks or same destination and confused to select the right one, then lowest metrics value is used by routing protocols to choose the best path after calculating and comparing the cost of each path learned by routing protocols. Each protocol has its own way to calculate metrics and compare its value as mentioned before EIGRP works on the combination of delay, load, bandwidth and reliability and OSPF uses only bandwidth and as different for other routing protocols.

2.2.2 Metrics Parameters of Routing Protocol

The metrics calculation of different routing protocols may results to select different path to same destination this is because different metrics values are used by different protocols. The following metrics are usually used in IP routing protocols:-

Hop Count: some protocols count numbers of routers means hops through the packet will traverse to reach the destination like in RIP packets are traverse on the path with least number of hops.

Bandwidth: After calculating the metrics if value is chosen bandwidth then path selected with highest bandwidth is preferable.

Load: Some protocols select their path according to the load on the link, the lowest load on link is consider the best path to reach destination.

Reliability: when reliability is chosen as metrics then path with highest reliability is selected, in this process reliability is calculated by the probability of the link failure in which can be calculated as from the previous recorded link failure or counting interface errors.

Cost: cost can be defined as a metrics or a policy combined with metrics because cost is basically a value which is set by administrator or IOS (Internet Operating System) to select best path.

2.3 Classification of Routing Protocols

Routing Protocols can be classified as:-

Static and Dynamic Routing Protocols

Distance Vector (DV) and Link-State Routing Protocols (LSR)

Classful and classless Routing Protocols

2.3.1 Static and Dynamic Routing Protocols

Static routing is basically used in small networks as its performance is bad because routing table constructed manually in static routing and routes are also fixed at boot time of router so that is why whenever new network is added or deleted within Autonomous System (AM) network administrator have to update it manually. Therefore it has good advantage in small network in which system administrator have full control of the network but on large networks this technology fails because it is hard to manage rapid changes in network topology and configure all routes manually.

On the other hand Dynamic Routing Protocols routing is more widely used in large networks because in this routing table is created automatically and updated by message exchanging with adjacent routers, which means each router in the network have information about all other routers in the network and whenever any router is added or deleted the routing table is updated by different update methods like periodic update and trigger updates. The best route in dynamic routing protocol is based on their individual metrics and rules. Not only this there are many other reason of choosing Dynamic Routing instead of Static and for Dynamic Routing, route instability and creating routing loops are only the drawbacks which may cause.

The most known Dynamic protocols are:-

RIP – A Distance Vector Interior Routing Protocol

IGRP – The Distance Vector Interior Routing Protocol by Cisco

OSPF – A Link-State Interior Routing Protocol

IS-IS – A Link-State Interior Routing Protocol

EIGRP – The Advanced Distance Vector Interior Routing Protocol by Cisco

BGP – A Path Vector Exterior Routing Protocol.

2.3.2 Distance Vector Routing Protocols

Distance Vector Routing determines the best path by calculating the distance to reach the destination, as the name indicates Distance means the how far is destination by hop count metrics and Vector of distance represents term of next hop router or exit interface. Distance Vector Routing Protocols works on the basis of Bellman-Ford algorithm in which routing table is created and updated periodically by broadcasting the entire routing table to each of its neighbour.

In Distance Vector each router maintains a distance vector for each destination which contains the information of next hop, destination ID and the shortest distance. This Protocols works on periodic advertisement of the shortest path by each router for example router sends its Distance Vector to its neighbours periodically containing the information of shortest path then the router in neighbour receives the information and updates its routing table and send the updated table periodically to its own neighbour and this process is continue works on the entire network in the time range of 10-90 seconds as depend on different Distance Vector Routing Protocols. In these protocols the router does not have the information of the entire path to the destination router. Router only counts the number of hops and has only the information of the direction and the interface from where the packet can be forwarded. Different metrics are used to update the information by distance vector protocols like in EIGRP the diffusion algorithm is used to select the cost of path to reach the destination.

Advantage and Disadvantage of Distance Vector Routing

The main advantages of Distance Vector Routing are as follows:-

Simple and easy to understand as they work on the basis of router advertising processes but these protocols are efficient in smaller networks

Distance Vector Routing Protocols are very easy to configure as just need to enable it on router interface and also they are very easy to manage.

Main Disadvantages:-

Large Routing tables in large networks, results as bad performance because thousands entries in routing table.

Creating loops and slow convergence

Problems with Scalability and not good in hierarchical routing

Although by split horizon rule and triggered updates, Distance Routing Protocols are boosted as result convergence speed is increased.

2.3.3 Link-State Routing Protocols

Link-State Routing (LSR) Protocols are those dynamic routing protocols which works DIJKSTRA’S Shortest Path First (SPF) algorithm that is why this protocol is also known as Shortest Path First Protocol. The router configured with LSR protocol will always chose the shortest path to reach the destination in network. In Link-State routing protocols the information is stored in database called Link-State database and this routing information is exchange among all routers in network through Link-State Advertisements (LSA). If there is any link added or changed in the network topology then LSAs is flooded to all the neighbour nodes by which routing table are updated information is stored in their own database which describes the topology of the network.

The database in these protocols contains the information cost of the each link in the network and this cost is calculated by algorithm called DIJKSTRA’S algorithm and the cost of each link can also be set by administrator. After all Link-State routing protocols have excellent flexibility but more complex as compare to Distance Vector and LSR protocols have less broadcast traffic. The most known LSR Protocols are Open Shortest Path First (OSPF) and Intermediate System to Intermediate System (IS-IS).

Advantage and Disadvantage of Link-State Routing

Each router in Link-State Routing Protocol calculate the route independently, the main advantages are as follow:

LSR have small Routing table which makes it react fast whenever their is change in network.

LSR also have low network overhead and the size of the packet sent in network is very small.

Drawbacks of Link-State Routing:

Configuration is difficult which results use of large memory space.

More complex as compare to Distance Vector.

2.3.4 Classful and Classless Routing Protocols

Depending on the subnet mask the routing protocols can be separated as Classful and Classless routing.

Classful:

The Classful routing contains the same subnet mask in the network topology and the Classful routing protocols never send any information regarding subnet mask in their routing updates. The router does not belong to same network then Classful subnet mask will be applied to the route.

Classful routing protocols are not widely used because they doesn’t support VSLM (Variable Length Subnet Masks) and also they cannot support discontinuous networks.

Classless:

Classless routing protocols are just opposite to Classful as in this the subnet mask varies in the network topology and also subnet mask and network address both are included in routing updates. EIGRP and OSPF are also belongs to classless routing protocols.

3.0 Enhanced Interior Gateway Routing Protocol (EIGRP)

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EIGRP is Cisco proprietary protocol and this is enhanced version of Interior Gateway Routing Protocol (IGRP) [7], EIGRP was developed in 1992 and now days this protocols is being consider as more scalable for both large and medium networks. Diffusion Update Algorithm (DUAL) is used in EIGRP for calculating the routes to destination and also EIGRP has both properties of Link-State and Distance Vector Routing Protocols as it creates neighbour relationships and advertises the routes in network topology that is why it also called as Hybrid Protocol.

3.1 EIGRP Components

EIGRP rely on the following four components:-

3.1.1 Diffusion Update Algorithm (DUAL)

EIGRP uses DUAL by which loops are avoided in network and this mechanism is process by following concepts of DUAL:-

Successor

Successor means the first router or the first hop across network which provides the least-cost path to the destination.

Feasible Distance

The lowest cost required to reach the destination is basically known as Feasible Distance.

Reported Distance

The cost of router to reach a destination in a network is known by reported distance

Feasible Successor

Feasible Successor provides the loop free backup path to the destination, basically Feasible Successor if neighbour router in network.

Feasible Condition

This is totally depend on the value reported distance and feasible distance to select the Feasible Successor, means the value of advertised Reported Distance by router to destination should be less than feasible destination to the same distance.

3.1.2 Neighbour Discovery and Recovery

This method allows routers to update their table dynamically with the information of other directly connected routers to the network and this information is exchange between routers with very low overhead as sending HELLO packets periodically throughout the network, router verify the connection with neighbour router by receiving HELLO packets from it. Usually these HELLO packets are sent periodically after every 5 seconds in high speed networks and with these HELLO packets advertise a HOLD time each time when they are sent by a router to make sure the connection is alive by receiving HELLO packets back. In EIGRP the default hold time is 15 seconds.

By exchanging these HELLO packets advertisements between each other in the network, router updates their outing table, if the any router doesn’t receive HELLO packets in between the HOLD time of EIGRP then the neighbour router will be discarded from the routing table.

3.1.3 Reliable Transport Protocol

This protocol is used by EIGRP for guaranteed and ordered delivery of EIGRP packets to all the neighbour routers in the network and also Reliable Transport Protocol supports intermix transmission of unicast or multicast packets. EIGRP packets are different; some of the packets are reliably transmitted as required and some do not need any reliability for transmission although reliability is provided whenever there is need.

3.1.4 Protocol Dependent Module

To support different network layer protocols, EIGRP uses PDM (Protocol Dependent Module) like Internet Packet Exchange (IPX) and Apple Talk.

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3.4 Advantages and Disadvantages in EIGRP

The main advantage of EIGRP routing protocol are:-

Loop free routes are providing by EIGRP routing protocol.

The configuration of EIGRP is very easy as compare to OSPF.

Low convergence time

EIGRP can work with VLSM (Variable Length Subnet Mask)

Routing update authentication is also supported by EIGRP

Disadvantages;

The main disadvantage is EIGRP is Cisco Proprietary so can be use only on Cisco products.

Routers from other vendors are not able to utilize EIGRP.

4.0 Open Shortest Path First

OSPF is Link-State Interior Gateway Routing Protocol and it can use by other product as well because it is not Cisco Proprietary. OSPF works with single Autonomous system and distribute the information across the network. In OSPF the cost of interface is calculated by bandwidth and this cost is inversely proportional to bandwidth, Lower cost requires higher bandwidth [3]. As mentioned before OSPF routing protocols always select the lowest cost path to all available destinations with the help of DIJKSTRA Algorithm calculation.

4.1 Protocol Structure

The following information is included in OSPF protocol structure [2]

Version: – indicates the current version of OSPF.

Type: indicates five types of packets which are

HELLO Packets, Database Description (DBD), Link-State Request (LSR), Link-State Update (LSU) and Link-State Acknowledgement (LSAck).

Packet Length

Router ID

Area ID

Checksum

Au Type

Authentication.

5. Related Works and Research

There are many comparative analysis of EIGRP, OSPF and other related routing protocols have been proposed and still research is going on some of them are given below.

Performance comparisons between OSPF and EIGRP in tactical IP networks. [18]

Dynamic Routing Protocol Implementation Decision between EIGRP, OSPF and RIP Based on Technical Background Using OPNET Modeler. [19]

Dynamic routing protocol performance in a fault- tolerant Ethernet-based IP network. [20]

And many more other research related to this topic but there are very few comparison and analysis of OSPF and EIGRP routing protocols for real-time traffic. In this project comparative analysis of two most popular routing protocols EIGRP and OSPF will be done in Cisco packet Tracer with different scenarios in terms of metrics performance. Further detailed information will be included as theoretically of all related routing protocols.

Conclusion

This contextual report was presented as the part of BSc Computer Networking final year project on Routing Protocols to provide the overview of the project information and literature research and also as Project Initiation Document, in this report the purpose of the project is clearly mentioned and further artefact will be designed and implement later with more detailed information as scheduled.