Wednesday, January 2, 2013

Which Routing Protocol To Select? OSPF Vs EIGRP

Most of the times, network administrators and planning guys look forward to understand which routing protocol are best to deploy for their network. The selection criteria between OSPF and EIGRP based on the below points:-

1. Between OSPF and EIGRP which one is the best to deploy and why?
2. Which protocol converges faster and highly available?
3. Which protocol uses fewer resources?
4. Which protocol is easier to deploy and operate?
5. Which protocol is easier to understand and configure?
6. Which protocol is easier to scale in large network?
7. Which protocol is more scalable and easy to adopt changes?

Every protocol has its own merits and de-merits. Between OSPF which is a link state routing protocol in its own area and becomes a distance vector routing protocol from one area to another and EIGRP is a distance vector routing protocol, In fact, its not a pure DV routing protocol.

Convergence speed depends on the number of routers and routes involved in the network. The more the number, less the convergence time. Convergence speed depends on various attributes defined in Fast Convergence Tools.

At broader level below are few points which can be used as high level to understand the protocol at its best:-

1. EIGRP uses metric based on bandwidth, delay, reliability, load and MTU whereas OSPF uses interface cost which is inversely proportional to bandwidth. EIGRP is considered as best in terms of selecting the path on different attributes.
2. EIGRP is proprietary to CISCO whereas OSPF is based on OPEN Standard.
3. EIGRP sends hop by hop query when feasible successor is not found whereas OSPF syncs its LSA(LSA1, LSA2, LSA3, LSA4 and LSA5) database whenever there is change in network topology. EIGRP is considered as best as it minimizes the routing information.
4. EIGRP is simpler to understand whereas OSPF has lot of things to understand. It depends how comfort you are to select out of these.
5. EIGRP does automatic summarization whereas OSPF doesn’t.
6. EIGRP does support both equal and unequal cost load sharing whereas OSPF doesn’t.
7. EIGRP limits the usage by 50% of the link bandwidth whereas OSPF does 100%.
8. EIGRP is faster to converge when it has feasible successor but OSPF doesn’t. Still there are lot of tools available to make OSPF better in terms of convergence.

Even after so many years, we can’t say which protocol is best over another. All it depends on your business requirement, understanding, behavior of deployed applications and network design. So decision is absolutely yours.

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