EIGRP Technology

Hello Folks, How you doing?. I hope i't going good. Well if you guys remembered we talked about Eigrp Concept and terminology last time. This time we will discuss Eigrp Technology.

So here we go let's discuss it in details. It includes many new ones, Representing an improvement in operating efficiency, speed of convergence, or functionality relative to IGRP and other routing protocols. There are four categories of technology and these technologies fall in one of the following four categories:

•        Neighbour discovery and recovery
•          Reliable Transport Protocol
•          DUAL finite-state machine algorithm
•          Modules which are Protocol-dependent

Relationship with their neighbours are not established in Simple distance vector routers. RIP and IGRP routers merely broadcast or multicast updates on configured interfaces. While Relationship with their neighbours are made possible in EIGRP routers, this is the feature that OSPF has.

EIGRP routers establish adjacencies with neighbour routers by using small hello packets. which are sent by default every five seconds.As long as EIGRP receiving hello packets from known neighbours, those neighbours and their routes remain viable or passive. By forming adjacencies, EIGRP routers do these thng. Firstly it Dynamically learn of new routes that join their network. Secondly it Identify routers that become either unreachable or inoperable. Thirdly Rediscover routers that had previously been unreachable

Reliable Transport Protocol (RTP): This protocol is used by EIGRP to achieve many purpose. Let’s discuss it. What significanse does it hold for EIGRP. RTP is a transport-layer protocol that can guarantee ordered delivery of EIGRP packets to all neighbours. On an IP network, hosts use TCP to sequence packets and ensure their timely delivery. However, EIGRP is protocol-independent. This means it does not rely on TCP/IP to exchange routing information the way that RIP, IGRP, and OSPF do. To stay independent of IP, EIGRP uses RTP as its own proprietary transport-layer protocol to guarantee delivery of routing information.

EIGRP can call on Reliable transport protocol, to provide reliable or unreliable service as the situation warrants. For Instanse, hello packets do not require the overhead of reliable delivery because they are frequent and should be kept small. Nevertheless, the reliable delivery of other routing information can actually speed convergence, because EIGRP routers are not waiting for a timer to expire before they retransmit.

EIGRP using RTP can multicast and unicast to different peers simultaneously, which means that efficiency will be maximum.

Diffusing Update Algorithm (DUAL) is The centrepiece of EIGRP, which is known as EIGRP route-calculation engine. DUAL finite-state machine (FSM) is the feature or technology behind it. An FSM is known as an algorithm engine. FSMs define a set of possible states that something can go through, what events cause those states, and what events result from those states. To determine How a device, computer program, or routing algorithm will react to a set of input events Designers use FSM. The DUAL FSM contains all the logic required to calculate and compare routes in an EIGRP network.

All the routes advertised by neighbours tracked by DUAL. Composite metrics of each route are used to compare routes Advertised. DUAL ensure that each path is loop free. DUAL inserts lowest cost paths into the routing table. These primary routes are known as successor routes. Topology table contain a copy of the successor routes.

EIGRP keeps important route and topology information readily available in a neighbour table and a topology table. These tables supply DUAL with comprehensive route information in case of network disruption. DUAL use the information in these tables to selects alternate routes quickly by. DUAL search an alternative route, path or feasible successor, in the topology table, if there is a failure of a link.

Modular design is one of the best features of EIGRP. It has proven to be most scalable and adaptable. Support for routed protocols, such as IP, IPX, and AppleTalk, are included in EIGRP through PDMs. In theory, EIGRP can easily adapt to new or revised routed protocols, such as IPv6, by adding protocol-dependent modules.

Each PDM is responsible for all functions related to its specific routed protocol. The IP-EIGRP module is responsible for the following:

• Transferring and receiving EIGRP packets that bear IP data
• Informing DUAL of new IP routing information that is received
• Looking after or maintaining the results of DUAL routing decisions in the IP routing table
• Furthermore Redistributing routing information that was learned by other IP-capable routing protocols