Difference between EIGRP and OSPF

Both EIGRP and OSPF are interior gateway routing protocols. The aim of both EIGRP and OSPF is to choose the best route to transfer information from source to destination with the help of routers.

In this article, you will learn the difference between EIGRP and OSPF, but before that, let us know the meaning of EIGRP and OSPF.

What do you mean by EIGRP?

EIGRP is an abbreviation for Enhanced Interior Gateway Routing Protocol. Sharing of data from one router to neighbouring routers is known as EIGRP.

It was designed by Cisco Systems. As EIGRP is Cisco proprietary, if your internet network all routers are of Cisco, you can configure EIGRP. But, if some routers are from a different company, then you cannot use EIGRP as a routing protocol because routers of other vendors will not understand EIGRP, so it is essential to have all Cisco company routers.

It is the successor of IGRP (Interior Gateway Routing Protocol), which means EIGRP is the improved version of IGRP. It can use four metrics which are delay, bandwidth, load and link reliability. These metrics find the best path to transfer the data packets. By default, it uses bandwidth and delay metrics to choose the path, but we can configure EIGRP to use load and reliability.

The router performs calculations based on the DUAL (Diffusing-Update Algorithm) formula to select the most efficient route to a destination. It is also called a hybrid routing protocol and uses a link-state routing protocol and distance vector.

It supports both IP addresses, IPv4 and IPv6. Routers can exchange information easily and efficiently. EIGRP is a dynamic routing protocol we use to find the best way to transfer data from one particular point to another. It is designed to be used within a single autonomous system.

It uses certain messages like hello message, NULL update, full update, partial update, query message, reply message and acknowledgement message to tell the next router about the link.  It sends data from one router to another.

Hello message is used to let the other routers know that they are still alive in order to maintain the neighbour connection. Hello message is sent to the router by default every 5 seconds, and find the best way to share the data.

What do you mean by OSPF?

OSPF is the short term used for Open Shortest Path First. It is a dynamic routing protocol that dynamically learns the routes of other routers and advertises the information to other OSPF-speaking routers so that each router can receive the information. OSPF monitors the status of all network connections or links between itself and the network; that is why it is also known as the link-state routing protocol.

It is the most popularly used Internal Gateway Protocol (IGP). It works within an autonomous system. It uses Transport IP, Protocol Type 89. It uses Shortest Path First Algorithm or Link State Routing Algorithm. Dijkstra, a Dutch computer scientist, designed this algorithm; hence it is also called Dijkstra's algorithm. It supports Variable Length Subnet Mask (VLSM) and is placed in the classless routing protocol.

OSPF chooses the best route, which has the lowest cost path from source to destination, so all router interfaces configure cost based on bandwidth, or you can set it explicitly, i.e., manual configuration.

The primary difference between EIGRP and OSPF are as follows:

EIGRP	OSPF
The complete form of EIGRP is Enhanced Interior Gateway Protocol.	The complete form of OSPF is Open Shortest Path First.
It is a hybrid protocol type.	It is a link-state protocol type.
It uses bandwidth and delay metrics to find the shortest route.	It uses cost metrics to find the quickest and shortest path.
It is owned by Cisco Systems.	It is based on ISTF Open Standard.
It requires less CPU and memory.	It needs a high CPU and memory.
It is effortless to implement, but there is no provision for auto-summary.	It isn't easy to implement.
The algorithm it uses is a DUAL distance vector.	The algorithm it uses is the Dijkstra link state.
No hierarchical design	Hierarchical design
It has a fast convergence time.	It has a slow convergence time.
It has unequal path load balancing.	It does not contain unequal path load balancing.
Slow and large networks.	Large network.
It has support for IPX and AppleTalk.	It does not support IPX and AppleTalk.
Filtering and summarization are possible anywhere in the network.	Filtering and summarization are possible only on ASBRs and ABRs.
The multicast address of EIGRP is 224.0.0.10.	OSPF's multicast address is 224.0.0.5 and 224.0.0.6.

You have learned the difference between EIGRP and OSPF in the above table.

We conclude that the main difference between EIGRP and OSPF is that EIGRP finds the shortest path to transfer data based on four metrics: bandwidth, load, link reliability and delay. In comparison, OSPF finds the shortest way based on cost metrics.