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Difference between IGRP and EIGRP

Last Updated : 11 Jul, 2025

IGRP and EIGRP are two developed routing protocols that belong to the Cisco Systems company. IGRP is an older distance-vector protocol that was built for use within a single autonomous system (AS). It was introduced to overcome the shortcomings of RIP, especially in a large network. EIGRP on the other hand is an enhanced version of IGRP which brings some improvements in the protocol thereby making it a better choice. To reach the appropriate conclusion network administrators must familiarize themselves with the features discriminating IGRP from EIGRP.

Interior Gateway Routing Protocol (IGRP)

The Interior Gateway Routing Protocol is the routing protocol. It is also a distance vector routing protocol. In this, the Bellman-Ford algorithm is used. The least hop count in IGRP is 255. 

Advantages of IGRP

  • Multi-metric Routing: In calculating the best path, IGRP incorporates more than one metric and hence is more effective than RIP.
  • Scalability: Basically, IGRP is smarter in handling larger networks compared with RIP due to multiple metrics support and enhanced larger maximum hop count.
  • Reliability: IGRP do integration of the bandwidth and delay in the routing decision which will give a more reliable routing path.

Disadvantages of IGRP

  • Slow Convergence: The major disadvantage to using IGRP is that it has relatively high convergence times, especially in large networks – this can cause temporary routing loops, or routing tables that are inconsistent.
  • Outdated: IGRP is rather dated at this point and was not supported in current AIM and Cisco IOS models and is thus not highly relevant in today’s networks.
  • Inefficiency: This makes IGRP like other distance-vector protocols where updates are based on periodic distribution and thus may cause wastage of traffic and bandwidth in the network.

Enhanced Interior Gateway Routing Protocol (EIGRP)

Enhanced Interior Gateway Routing Protocol is routing protocol like Interior Gateway Routing Protocol. It is the link state routing protocol as well as vector routing protocol. 

Advantages of EIGRP

  • Rapid Convergence: EIGRP employs the Diffusing Update Algorithm (DUAL) in order to achieve convergence at lightening speed and thereby avoid the worst-case scenario – that of routing loops.
  • Scalability: EIGRP is very scalable unlike some of the other routing protocols that can only support small networks. The protocol is capable of managing huge routing tables as well as intricate network configurations.
  • Reduced Bandwidth Usage: EIGRP provides only the changes in the routing table and not the entire table, hence minimizing the usage of the bandwidth in the network.
  • Classless Routing: EIGRP provides Variable Length Subnet Masking (VLSM) for the effective use of the IP address.

Disadvantages of EIGRP

  • Proprietary Protocol: Let us start with EIGRP, this was initially a Cisco’s owned protocol and could only be implemented on Cisco equipment’s. Although they are proprietary standards, some of them have been made open in the recent past.
  • Complexity: Compared to the simpler RIP or even OSPF, but EIGRP is harder to configure and manage, therefore it requires members’ knowledge.
  • Resource Intensive: EIGRP can consume more system resource than RIP and IGRP, this is more particularly so in very large networks since it uses more CPU and memory in routers.

Difference between IGRP and EIGRP

IGRPEIGRP
IGRP stands for Interior Gateway Routing Protocol.EIGRP stands for Enhanced Interior Gateway Routing Protocol.
Interior Gateway Routing Protocol is Classful routing technique.While Enhanced Interior Gateway Routing Protocol is a classless routing technique.
IGRP is a slow convergence.While it is a fast convergence.
In IGRP, Bellman ford algorithm is used.While in this, DUAL (Diffusing Update Algorithm) is used.
IGRP needs more or high bandwidth.While EIGRP needs low or less bandwidth.
The least hop count in IGRP is 255.While the least hop count in EIGRP is 256.
It provides 24 bits for bandwidth and delay.While it provides 32 bits for bandwidth and delay.
It requires administrative distance of 100.It requires administrative distance of 90.
It only supports multi-part routing but not areas or tables.Neighbor tables, topology tables and routing tables are used for routing.
The symbol "I" is used in the routing table to represent IGRP.The symbol "D" is used in the routing table to represent EIGRP.
It does not support Variable Length Subnet Mask (VLSM).It supports Variable Length Subnet Mask (VLSM).

Conclusion

IGRP and EIGRP are two of the old but key routing protocols ever implemented on the Cisco networks with EIGRP being a more advanced version of IGRP. As an improvement over RIP, IGRP has been implemented but is now rarely used due to a number of drawbacks and has been succeeded by EIGRP, which provides faster convergence, a larger scalability and optimizes the availability of network resources. Although IGRP is no longer in use, analyzing its working gives suitable background information that can help better assess the features that EIGRP brought to the table. Thus, EIGRP can still be considered one of the most efficient for the modern networks, especially if the networks are dominated by the equipment of Cisco company.

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