Implementing the EIGRP

It is basically defined as (EIGRP)-Enhanced Interior Gateway Routing Protocol.

It an advanced distance vector routing protocol which was developed by the Cisco. Different sort of topologies and the media are suited for the EIGRP. When the network was in a well-designed and works fine, then the EIGRP scales will provides very quick and extreme convergence times in a minimal overhead. And in the Cisco devices EIGRP is a popular choice for routing the protocols.

Introduction of EIGRP:

It combines the distance vector routing protocols and the advantages of link-state. The EIGRP is a hybrid routing protocol or an advance distance vector which are included in the following features.

• Load balancing: unequal metric load balancing was enabled by the EIGRP. Which helps in the traffic flow in the networks to be better for the administrators.
• Easy summarization: summary routes are created anywhere by the administrators which was enabled by the EIGRP and it was enabled within the network. Rather than to depends on the traditional vector distance and performing the class full at major network places of boundaries.
• Classless routing: EIGRP will advertises a routing mask of various destination network because it is a class routing protocol and it enables the EIGRP to support the (VLSM) variable-length subnet masks and various discontinues Subnetworks.
• Reducing the usage of the bandwidth: the periodic updates are not formed in the EIGRP. And to these when there is a change in path or the metric of the route it sends a partial updates. When information the path changes, an update was sent by the DUAL about that certain link not rather than the entire table.
• Less Overhead: rather than using the broadcast, EIGRP uses the multicast and the unicast. And to this effect the stations at the end are unaffected and requests for the topology information.
• Support of multiple network layer: IP version 6(IPv6), IP version 4(IPv4), AppleTalk, and the Novell internetwork packet Exchange (IPX) are mostly supported by the EIGRP, those area also used in the protocol-dependent modules (PDM). And these PDM are responsible for the network layer protocol requirements. 

Rapid Convergence: And to obtain the rapid convergence the (DUAL) Diffusing Update Algorithm are used by the EIGRP. EIGRP stores all the data and makes a backup which was available from the routers which are using it. And if there was no backup or an appropriate router exits in the system or in the local routing table then the EIGRP queries the neighbours to implement another source of alternate route.  

And in the EIGRP the route are described according to their work the best route is known as a successor route and the backup route is called a feasible successor. The following two types of parameters are used in EIGRP in order to determine the best route and the backup route.

• Feasible Distance: The distance between the advertised particular network and from the neighbour plus for to reach the neighbour.
• Advertised Distance: The metric of a EIGRP to their neighbour for to reach a certain required network.

Configuring and Verifying EIGRP

Network commands and router eigrp are used to create the EIGRP routing process. To be noted that an (AS) autonomous system number is required for the EIGRP. While routing in the internet with the (BGP) Border Gateway Protocol the autonomous system is need not be registered in this case. And to exchange the routing information among the routers all should using the same AS number with in the same AS number. The following figure shows the configuration of EIGRP in a simple form of network.                                                

To the router which is directly connected the network command defines an important and major network number.

Those which have an IP address and the networks are specified by the network commands have the EIGRP looks for the interfaces and with the command the EIGRP process in this sort of interfaces.

The command are shown below in a table for example:

Command	Description
Router eigrp 100	It helps to enable the routing process for EIGRP in AS 100
Network 172.16.0.0	It will associates network 172.16.0.0 with the EIGRP
Network 10.0.0.0	It is associating the network with 10.0.0.0 along the EIGRP routing process

In these the updates are send by EIGRP with the interface of the networks 10.0.0.0 and the 172.16.0.0. And these includes the information on the 10.0.0.0 and 172.16.0.0 and the any networks which are learning the EIGRP.

At the classful boundary the EIGRP summarizes the rotes in an automatically manner. And in some case the requirement of the automatic summarization is need not required. When consider an example of discontinuous networks have occurred there is a need of disabling the automatic summarization in order to minimize the router confusion.

There we should use the no auto-summary command in the EIGRP router configuration mode in order to disable the automatic summarization.

Various sort of commands are used in the display information in order to show the display information on the working and operation of the protocol, after the EIGRP is enabled. The current EIGRP entries in the routing table are displayed by using the command show ip route eigrp.

The current state and the parameters of the active routing protocols process are showed by using the command show ip protocols.  EIGRP AS number is showed by the command, it does also displays the neighbour, distance information, display filtering and the redistribution numbers. And the advertised in the router by the protocol and the network.

The following table describes the various significant fields which are generated by the show ip eigrp interfaces output.

Field	Description
Interface	EIGRP is configured in the interface
Pending Routes	Various number of the different routes in the packets which are in queue and waiting to be sent.
Mean SRTT	Average smoothed round-trip time (SRTT) interval (in milliseconds) for all neighbours on the interface
Multicast Flow Timer	Number of milliseconds to wait for acknowledgment of a multicast packet by all neighbours before transmitting the next multicast packet
Peers	The number of EIGRP neighbours in the interface which are connected directly
Pacing Time Reliable/Un	Number of milliseconds to wait after transmitting reliable and unreliable packets
Xmit Queue Reliable/Un	Various number of packets which are remaining in the reliable and unreliable queues