Difference between IGRP and EIGRP

In computer networking, Interior Gateway Routing Protocol (IGRP) and Enhanced Interior Gateway Routing Protocol (EIGRP) are two routing protocols designed for communication between routers within the same network. In this article, we will compare IGRP and EIGRP and discern their differences.

Definition of IGRP

IGRP is a routing protocol that was introduced by Cisco in the 1980s. It is a Distance Vector Protocol, which means it uses only the distance (number of hops) to discover the best path to a destination network. It is classful, meaning that it only supports major network classes (A, B, and C). It has a maximum hop count of 100, which means that it can only support networks with a maximum diameter of 15 hops.

Definition of EIGRP

Enhanced Interior Gateway Routing Protocol (EIGRP) is another routing protocol developed by Cisco. It is an advanced version of IGRP and was introduced in the 1990s. It uses a composite metric that takes into account the bandwidth, delay, reliability, load, and MTU of a network. It supports both classful and classless routing, meaning it can use VLSM. It has a maximum hop count of 224 and can support networks with a diameter of up to 254 hops.

Differences between IGRP and EIGRP

The key differences between IGRP and EIGRP are:

Metric Calculation

The way the two protocols calculate the best path to a destination network is different. IGRP uses only the number of hops, while EIGRP uses a composite metric that takes into account several factors such as bandwidth, delay, reliability, load, and MTU. Therefore, EIGRP is more efficient and accurate in finding the best path to a destination network.

Network Size

IGRP supports only major network classes (A, B, and C) and has a maximum hop count of 100. Therefore, it can support networks with a maximum diameter of 15 hops. On the other hand, EIGRP supports both classful and classless routing and has a maximum hop count of 224. As a result, it can support larger networks with up to 254 hops in diameter.

Protocol Type

IGRP is a Distance Vector Protocol, while EIGRP is a hybrid protocol that uses both Distance Vector and Link State Protocol features. EIGRP uses Diffusing Update Algorithm (DUAL) to calculate the best path to a destination network, which allows it to converge faster than IGRP.

Bandwidth Usage

Due to its simpler metric calculation and periodic updates, IGRP consumes less bandwidth than EIGRP. EIGRP, on the other hand, uses more bandwidth because it constantly calculates and updates its metric and routing table.

Convergence Time

EIGRP converges faster than IGRP due to its use of DUAL and quick adaptability to network changes. IGRP, on the other hand, can take longer to converge due to its slower updates and less accurate metric calculations.

Conclusion

In conclusion, IGRP and EIGRP are two routing protocols developed by Cisco for use in computer networks. IGRP is simpler and uses only the number of hops to calculate the best path to a destination network, while EIGRP is more advanced and uses a composite metric that takes several factors into account. Although both protocols have their strengths and weaknesses, EIGRP is generally more efficient and reliable for larger, more complex networks.