A critical evaluation of two complex interior routing gateway protocols

Interior Gateway Routing protocol is a protocol that “distributes routing information between routers belonging to an Autonomous System” (Moy, J., 1998) whereby computers or any device able to connect to the network can exchange data within their own domain and beyond by being routed externally through a border router.
Routing protocols can be divided into two methods, Distance Vector which contains both distance and direction to reach its destination whilst Link-state has a complete topology of an area and uses the cost to calculate the best possible path to the destination.

RIP (Routing Information Protocol) uses a basic hop count (Distance Vector) and doesn’t take into account the link bandwidth whereas IGRP and EIGRP both of which offer greater scalability use a composite metric based on bandwidth and delay but are both Cisco proprietary protocols. Since IOS version 12.2 and later, IGRP has been deprecated (Cisco Networking Academy., 2014) and superseded by EIGRP.
Of the following Link-State protocols, OSPF is perhaps the most widely used in large enterprise networks as there is a broad experience base and greater reference resources available, also there is support across different platform vendors when compared to EIGRP which is owned by Cisco. IS-IS has a niche place inside large Internet Service Provider networks where simpler programming, scalable and stable networks are paramount with the benefit of fewer compatibility issues but it has no multipoint or MBNA support which in enterprise networks would be a prerequisite especially if the network spans various sites and transcends borders (Doyle, Jeff., 2001).
In selecting my two protocols I have decided on EIGRP through a process of elimination and OSPF through a more pragmatic approach that will also mean that my evaluation includes a protocol from each of the two methods.

EIGRP (Enhanced Interior Gateway Routing Protocol) uses RTP (Reliable Transport Protocol) to form Neighbor Adjacencies and exchange the routing information with Hello packets. Once the router has received this routing information it places it in its Topology Table and runs DUAL (Diffusing Update Algorithm) algorithm placing the feasible successor into the topology table and the Successor (Best route) in the Routing Table. This adds up to reduced routing updates and therefore less bandwidth utilization and no broadcasts. If the route goes down the feasible successor it will automatically become the successor resulting in a quick convergence time.
EIGRP is more of a hybrid protocol as it has characteristics of a link-state protocol but initially it exchanges a full routing table between neighbors which is the main behavior of a Distance Vector protocol and therefore it is classified as such (Lammle, T., Tedder, W.,2014, pp.785).
OSPF (Open Shortest Path First) has a complete Topology overview of the whole network using LSA (Link State Advertisement) flood when sharing routing information via LSU (Link State Update) packets. The LSA contains the link state data which is shared with all routers in an area forming the Topology Table and by using this information it calculates the shortest and best path using the Dijkstra Algorithm which is then inserted into the Routing Table; however the computational power required by the Dijkstra Algorithm (Chandra, W., 2011) means a slower path generation compared to EIGRP.

Both protocols are classless, in that they borrow host bits of a classful address scheme to form additional subnets, unlike RIPv1 and IGRP were you are tied into only using classful boundaries. A network issue you might encounter is a classful IP address scheme which is segregated by a different class of IP address referred to as a Discontiguous network. This can occur through poor design or acquisitions and in this instance the easiest option available to you especially in large organizations, would be to implement EIGRP, unless you were to change the IP address scheme of one of the discontiguous networks.

Open Shortest Path First (OSPF) is an open standard thereby insuring the development and enhancement by different manufacturers and individuals. Enhanced Interior Gateway Protocol (EIGRP) was released as an “Informational RFC” (Anonymous., 2013) in 2013 as RFC 7868, so that other vendors can use it. Cisco retains control but has only published partial functionality which hasn’t made it attractive to other manufacturers and this is borne out as no other manufacturers at this stage incorporate EIGRP protocol in their devices.

Some of the perceived advantages of EIGRP in a production network is the multiprotcocol support it provides, such as support for IPX and AppleTalk (Zazuli, L., Mardedi, A., Rosidi, A., 2015). IPX from Novell for Netware Clients and AppleTalk are a suite of protocols developed by Apple for Macintosh, but with IPX being phased out since the mid-1990’s and AppleTalk since 2009 they have become legacy protocols so are no longer an advantage.
The references and articles reviewed for this assignment show that the analysis of EIGRP compared to OSPF had a slight performance advantage over OSPF (Zazuli, L., Mardedi, A., Rosidi, A., 2015) but a real caveat for these findings is that they have been conducted on Cisco Packet Tracer or GNS3 emulation software (Chandra, W., 2011) or both, but using only Cisco images as other manufacturers at this stage do not offer support for EIGRP.

In conclusion there are no hard and fast rules when deciding between OSPF and EIGRP as they both have their merits and are future-proof in that both support IPv4 and IPv6. Due to OSPF being an Open Standard it still has the market share for interior gateway protocols, although administration of OSPF when compared to EIGRP requires more resources and planning as it only supports contiguous networks making address conservation paramount in the design of the network. EIGRP will still be implemented in niche situations such as: organizations with kiosk stores; a network that is still running IGRP as EIGRP is backwardly compatible; or the acquisition of a network that has discontiguous networks that you need to join.
However, the ever increasing encroachment by other vendors, like Juniper Networks which have not included EIGRP on their hardware, has seen a year-on-year growth (Haranas, M., 2015) in market share, and a dramatic reduction of Cisco’s market share.


Al-Hadidi, M.R.A., Al-Gawagzeh, M.Y., Al-Zubi, N., (2014, August 1) ‘Performance Analysis of EIGRP via OSPF Based on OPNET and GNS3’, Research Journal of Applied Sciences, Engineering and Technology, Vol.8 (8), pp.989-994
Anonymous., (2013, March 7), ‘Enhanced Interior Gateway Routing Protocol (EIGRP) Informational RFC Frequently Asked Questions’, Cisco [Online]. Available at (Accessed 12 July 2016)

Bryant, Chris CCIE No12933. (2016) ‘CCNP Route 300-101 Study Guide’, Published in Great Britain for Amazon, pp. 20-40

Bryant, Chris CCIE No12933., (2016) ‘CCNP Route 300-101 Study Guide’, Published in Great Britain for Amazon, pp. 79-115

Chandra, W., (2011) ‘Performance Analysis of Dynamic Routing Protocol EIGRP and OSPF in IPv4 and IPv6 Networks’, First International Conference on Informatics and Computational Intelligence, pp.355-360 Cisco Networking Academy., (2014, March 24), ‘Cisco Networking Academy’s Introduction to Routing Dynamically’, Ciscopress [Online]. Available at (Accessed 9 June 2016)

Dey, G.K., Ahmed Md. M., Ahmmed, K.T.,(2015 November),’Performance Analysis and Redistribution among RIPv2, EIGRP & OSPF Routing Protocol’, 2015 International Conference on Computer and Information Engineering, pp.21-24

Doyle, Jeff., (2001), ‘IS-IS and OSPF: Network Design and Comparisons and Considerations’, Juniper Networks [Online]. Available at (Accessed 13 July 2016)

Haranas, M., (2015, November 24), ‘Report: Juniper Is Eating Cisco’s Lunch In U.S. Service Provider Routing Market’ , CRN Magazine [Online]. Available at (Accessed 14 July 2016)

Lammle, T., Tedder, W. (2014) CCNA Routing and Switching Deluxe Study Guide, Indianapolis, Indiana: John Wiley & Sons, Inc., pp.386-393

Lammle, T., Tedder, W. (2014) CCNA Routing and Switching Deluxe Study Guide, Indianapolis, Indiana: John Wiley & Sons, Inc., pp.784-792

Moy, J., (1998, April), ‘RFC markup version OSPF Version 2’, Internet Engineering Task Force [Online].
Available at (Accessed 12 July 2016)

Tetz, Edward. (2011) ‘Cisco Networking All-In-One for Dummies’, Indianapolis, Indiana: John Wiley & Sons, Inc., pp. 345-350 (Book 4, Chapter 1)

Vasos, H., (2015, February 25), ‘On the performance comparison of RIP,OSPF,IS-IS and EIGRP routing protocols’, Cornell University Library pp.1-6
Wallace, Kevin CCIE No.7945. (2015) ‘CCNP Routing and Switching ROUTE 300-101’, Indianapolis, Indiana: Cisco Press.

Zazuli, L., Mardedi, A., Rosidi, A., (2015, September 1),’ Developing Computer Networks Based on EIGRP Performance Comparison and OSPF’, International Journal of Advanced Computer Science and Applications, Vol.6(9), pp.80-86

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