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Difference between IGRP and EIGRP

IGRP (Interior Gateway Routing Protocol) and EIGRP (Enhanced EIGRP) are the two routing protocols used in routing operations. IGRP is a routing protocol of the distance vector internal gateway, but the EIGRP incorporates the characteristics of the routing of the connection status with the remote carrier routing protocol. There are several differences between IGRP and EIGRP, previously IGRP uses a classful routing method while EIGRP is a classless routing protocol. EIGRP provides better support for large-scale networking than IGRP.

Comparative graph

Basis for comparisonIGRPEIGRP
Expands to Routing protocol for internal gateways Improved routing protocol for internal gateways
Supported addressing technique classful Classless
Bits provided for bandwidth and delay 24 32
Count the hops 255 256
Convergence Slow Extremely fast
Update timers 90 seconds Only in any alteration
Algorithm Bellman ford DUAL
Administrative distance 100 90
Required bandwidth Of Pi Less

Definition of IGRP

IGRP (Internal Gateway Routing Protocol) allows the synchronized routing process between the gateways by exchanging routing information with neighboring gateways. The routing information contains the summary of detailed information about the network. There are several gateways involved in solving an optimization problem. This is the reason, known as a distributed algorithm in which each gateway assigned to a part of a problem.

The basic implementation of IGRP concerns TCP / IP routing together with various protocols. The IGRP protocol is an internal gateway routing protocol that is used within a group of networks connected and managed by a single entity or group of entities. The external gateway protocol is used to connect these network sets. IGRP a successor to RIP (Routing Information Protocol) which contains more functionality than the RIP. designed with advanced features to manage large and more complicated networks.

The limitation of IGRP that the routing cycle problem occurs. To avoid the routing cycle, IGRP neglects the newly generated data for a period of time when certain changes occur. Although, IGRP is easily configurable.

Definition of EIGRP

EIGRP (Enhanced Interior Gateway Routing Protocol) the improved version of IGRP that is enabled with many features that are not provided in other protocols. It is the origin of hybrid routing that is developed by combining the characteristics of remote carrier routing and link state routing. The advantages of EIGRP are simple to configure, efficient and secure, but its main advantage is that it supports classless routing not supported by IGRP. The PDM (Protocol Dependent Modules) describes the protocol requirements for the network layer and makes IGRP compatible with IPv4, IPX and AppleTalk.

  • The requirement of bandwidth and the overload generated in the EIGRP are lower than IGRP because it does not send periodic updates; instead, it sends the update only when changes are made to the route and the metric.
  • Convergence in EIGRP faster than other protocols, to obtain this, routers running EIGRP maintain backup routes to the destination for uncertain cases. If no backup route exists for the destination, the router sends the query to the adjacent router requesting the alternative route. This rapid convergence achieved with the help of DUAL (Diffusing Update Algorithm) .
  • EIGRP can create summary routes at any point on the network in a short period, instead of depending on the conventional distance vector algorithm in which only class addressing was allowed. Therefore, the route summary in rapid EIGRP.
  • It also provides the unequal load balancing metric to effectively spread the flow of traffic along the network.

Key differences between IGRP and EIGRP

  1. IGRP supports class addressing, while EIGRP allows the use of classless routing.
  2. For bandwidth and delay, the IGRP assigned to 24 bits. On the other hand, the EIGRP assigned with 32 bits for bandwidth and delay.
  3. The number of hops in IGRP 255 while 256 in the case of EIGRP.
  4. The convergence in slow IGRP compared to EIGRP.
  5. After every 90 seconds in IGRP, the periodic update is transmitted to the devices. On the contrary, EIGRP sends the update only if any changes occur.
  6. EIGRP follows a DUAL algorithm. As against, IGRP uses the ford bellman algorithm.
  7. The administrative distance of IGRP 100. In contrast, EIGRP routes have an administrative distance of 90.
  8. The bandwidth requirement in the IGRP is greater than the amount required in the EIGRP.


The routing performance of EIGRP has improved compared to IGRP because it has integrated the routing features of the connection state with remote carrier routing. The problem of redistribution of routes is eliminated by the EIGRP, while present in the IGRP.