Before we studying about Enhanced Interior Gateway Routing Protocol (EIGRP), have a look at IGRP. The full expansion of IGRP is Interior Gateway Routing Protocol, and is mainly used in following internets:

  1. OSI(Open System Interconnection).
  2. TCP/IP internets.

This protocol can be also be referred to as IGP.

For the interdomain routing protocol, the Exterior Gateway Protocol can be used. The technology used for (Interior Gateway Routing Protocol) is distance vector routing technology. The concept of this technology is that there is no need for knowing all the relationships between the routers(between the links) of that entire network. Each router has a distance that illustrates the corresponding destinations. When the router gets information, it will adjust the distance to the destination. Then it transfers it to the nearby routers.

In IGRP, the distance information can be illustrated or denoted by using the bandwidth, delay, load utilization a the link availability that is available.

We can say that this protocol(EIGRP) is an enhanced version of the protocol called IGRP. The technology used in the IGRP is also used in the EIGRP protocol, named as distance vector technology. Also, the distance information is the same as in the IGRP protocol. The only difference is that, in EIGRP,  it improves its operating efficiency and convergence properties. While retaining the existing investment, these features improve its architecture.

Working of EIGRP

The basic components of EIGRP:

1)Protocol Dependent Modules

2)Reliable Transport Protocol

3)Neighbor Discovery/Recovery

4)DUAL Dependent Modules

Protocol Dependent Modules:- This is mainly used for protocol-specific requirements and is responsible for the network layer. If we consider an example, the EIGRP packets that are encapsulated in the IP can be sent and receive by using the advantage of the IP-EIGRP module. The main two responsibilities of this protocol are the following:

⦁    Informs the DUAL of new information received.

⦁    Parsing EIGRP packets.

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Reliable transport protocol:- The main two advantages of using the reliable transport protocol are, they possess ordered and guaranteed delivery of packets to all the neighboring routers. It also provides the advantage that is it supports the intermixed transmission of the packets even if they are unicast or multicast. Some of the EIGRP packets are must possess reliability when they transfer. And some the EIGRP does not need this property, that is there is no need that the packet should be reliable. We can use the reliability characteristic for efficiency.

Neighbor discovery/recovery:- This is the process where the router will study all the routers that are connected to it in the network and this process is a dynamic process. And another responsibility of this router is it should find if the neighboring routers come unreachable or it’s not working properly. This can be done by using the advantage of hello packets. The hello packets are sent periodically.

DUAL Dependent Modules:- The route computation’s decision process can be illustrated by the DUAL finite-state machine. Also, it tracks its neighbors. The efficient loop paths can be selected by using the distance information by the DUAL. The route that is to be inserted to the routing table is selected by the DUAL is depended on the feasible successors.

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