EIGRP Routing Protocol & Configuration

EIGRP Routing Protocol & Configuration

~ ~

ma D

© 2

http: www.oscentre.co.nr//

A) EIGRP Definition

There is several terms on routing protocol, as we know RIP, IGRP/EIGRP, OSPF, BGP is major routing protocol. On my last article, I wrote about Routing Internet Protocol (RIP) and its configuration on Cisco machine (with Bosson Netsim). But in this section, as i've wrote on the title that i'll discuss about EIGRP and its configuration in Cisco machine. Before we step into configuration section, I want to explain a bit of EIGRP theory and what the relation with IGRP. As far as I know, EIGRP is a product development of IGRP basically. Abbreviation of IGRP refer to Interior Gateway Routing Protocol, it is a routing protocol developed in the mid-1980s by Cisco Systems, Inc. Cisco's principal goal in creating IGRP was to provide a robust protocol for routing within an autonomous system (AS) having arbitrarily complex topology and consisting of media with diverse bandwidth and delay characteristics.

Whereas EIGRP is short of Enhanced Interior Gateway Routing Protocol. With Software Release 9.21, Cisco introduced an enhanced version of IGRP that combines the advantages of link state protocols with the advantages of distance vector protocols. Enhanced IGRP incorporates the Diffusing Update Algorithm (DUAL) developed at SRI International by Dr. J.J. Garcia-Luna-Aceves. Enhanced IGRP includes the following features:

• Fast convergence---Enhanced IGRP uses DUAL to achieve convergence quickly. A router running Enhanced IGRP stores all of its neighbors' routing tables so that it can quickly adapt to alternate routes. If no appropriate route exists, Enhanced IGRP queries its neighbors to discover an alternate route. These queries propagate until an alternate route is found.

• Variable length subnet masks---Enhanced IGRP includes full support for variable length subnet masks. Subnet routes are automatically summarized on a network number boundary. In addition, Enhance IGRP can be configured to summarize on any bit boundary at any interface.

• Partial, bounded updates---Enhanced IGRP does not make periodic updates. Instead, it sends partial updates only when the metric for a route changes. Propagation of partial updates is automatically bounded so that only those routers that need the information are updated. As a result of these two capabilities, Enhanced IGRP consumes significantly less bandwidth than IGRP.

• Multiple network-layer support---Enhanced IGRP includes support for AppleTalk, IP, and Novell NetWare. The AppleTalk implementation redistributes routes learned from the Routing Table Maintenance Protocol (RTMP). The IP implementation redistributes routes learned from OSPF, Routing Information Protocol (RIP), IS-IS, Exterior Gateway Protocol (EGP), or Border Gateway Protocol (BGP). The Novell implementation redistributes routes learned from Novell RIP or Service Advertisement Protocol (SAP).

Enhanced IGRP features four new technologies:

• Neighbor discovery/recovery---Used by routers to dynamically learn about other routers on their directly attached networks. Routers must also discover when their neighbors become unreachable or inoperative. This process is achieved with low overhead by periodically sending small hello packets. As long as a router receives hello packets from a neighboring router, it assumes that the neighbor is functioning, and they can exchange routing information.

• Reliable Transport Protocol (RTP)---Responsible for guaranteed, ordered delivery of Enhanced IGRP packets to all neighbors. It supports intermixed transmission of multicast or unicast packets. For efficiency, only certain Enhanced IGRP packets are transmitted reliably. For example, on a multiaccess network that has multicast capabilities, such as Ethernet, it is not necessary to send hello packets reliably to all neighbors individually. For that reason, Enhanced IGRP sends a single multicast hello packet containing an indicator that informs the receivers that the packet need not be acknowledged. Other types of packets, such as updates, indicate in the packet that acknowledgment is required. RTP has a provision for sending multicast packets quickly when unacknowledged packets are pending, which helps ensure that convergence time remains low in the presence of varying speed links.

• DUAL finite state machine---Embodies the decision process for all route computations. It tracks all routes advertised by all neighbors. DUAL uses distance information to select efficient,

loop-free paths and selects routes for insertion in a routing table based on feasible successors. A feasible successor is a neighboring router used for packet forwarding that is a least-cost path to a destination that is guaranteed not to be part of a routing loop. When a neighbor changes a metric or when a topology change occurs, DUAL tests for feasible successors. If one is found, DUAL uses it to avoid recomputing the route unnecessarily. When there are no feasible successors but there are neighbors advertising the destination, a recomputation (also known as a diffusing computation) must occur to determine a new successor. Although recomputation is not processor intensive, it does affect convergence time, so it is advantageous to avoid unnecessary recomputations.

• Protocol-dependent modules---Responsible for network-layer protocol-specific requirements. For example, the IP-Enhanced IGRP module is responsible for sending and receiving Enhanced IGRP packets that are encapsulated in IP. IP-Enhanced IGRP is also responsible for parsing Enhanced IGRP packets and informing DUAL of the new information that has been received. IP-Enhanced IGRP asks DUAL to make routing decisions, the results of which are stored in the IP routing table. IP-Enhanced IGRP is responsible for redistributing routes learned by other IP routing protocols.

The consistent and superior performance of Enhanced IGRP relies on several new features: • Packet types

• Neighbor tables • Topology tables • Route states • Route tagging

Perhaps you will find out more article which discuss about IGRP / EIGRP on Google, but I also suggest you to visit Cisco's site. Because this article is related with how to configure EIGRP on Cisco machine, and Cisco has provide more complete manual guide for all configuration of routing protocol include EIGRP. On my article, I'll show a basic of EIGRP's configuration to you. As usual, the network configuration based on my experiment with my favourite Cisco simulator called GNS3...(^_^)

B) Network Topology & Specification

This is a simple network topology and its specification which I use on my experiment. I hope you enjoy it !

Specification :

1 ethernet (e2/0) on network 10.0.1.0/24

2. Router Cisco 3600 as Bimasakti router with :

 1 serial (s1/0) on network 167.205.44.0/24  1 ethernet (e2/0) on network 192.168.7.0/26 3. 1 PC client

4. 1 PC server

Ok..i don't want platitude any more, so let's step on the configuration. I assume that you have familiar with GNS3, so I don't need to explain how to use and configure its facilities.

C) Configuration

!Press Enter to start exec mode, and type enable to privilege mode Router>enable

Router#

!Configure hostname & interface Router#hostname Andromeda Andromeda#configure terminal Andromeda(config)#interface s1/0 Andromeda(config-if)#ip address 167.205.44.2 255.255.255.192 Andromeda(config-if)#no shutdown Andromeda(config-if)#interface e2/0 Andromeda(config-if)#ip address 10.1.0.1 255.255.0.0 Andromeda(config-if)#no shutdown Andromeda(config-if)#end !Check your configuration

Andromeda#show running-config !Configure routing protocol with EIGRP Andromeda#configure terminal Andromeda(config)#router eigrp 1 Andromeda(config-router)#network 10.1.0.0 0.0.255.255 Andromeda(config-router)#network 167.205.44.0 0.0.0.63 Andromeda(config-router)#no auto-summary Andromeda(config-router)#end Andromeda#

!Don't forget to check your configuration In my complete configuration is seem like this :

!

version 12.2

service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname Andromeda ! boot-start-marker boot-end-marker !

logging console emergencies !

ip subnet-zero ip cef

! !

no mpls traffic-eng auto-bw timers frequency 0 call rsvp-sync

interface FastEthernet0/0 no ip address shutdown duplex half no clns route-cache ! interface Serial1/0 ip address 167.205.44.2 255.255.255.192 serial restart-delay 0 no clns route-cache ! interface Serial1/1 no ip address shutdown serial restart-delay 0 no clns route-cache ! interface Serial1/2 no ip address shutdown serial restart-delay 0 no clns route-cache ! interface Serial1/3 no ip address shutdown serial restart-delay 0 no clns route-cache ! interface Ethernet2/0 ip address 10.1.0.1 255.255.0.0 duplex half no clns route-cache ! interface Ethernet2/1 no ip address shutdown duplex half no clns route-cache ! interface Ethernet2/2 no ip address shutdown duplex half no clns route-cache ! interface Ethernet2/3 no ip address shutdown duplex half no clns route-cache ! router eigrp 1 network 10.1.0.0 0.0.255.255 network 167.205.44.0 0.0.0.63 no auto-summary ! ip classless ! no ip http server !

!

dial-peer cor custom ! ! line con 0 logging synchronous stopbits 1 line aux 0 stopbits 1 line vty 0 4 no login ! end  Bimasakti router

!Press Enter to start exec mode, and type enable to privilege mode Router>enable

Router#

!Configure hostname & interface Router#hostname Bimasakti Bimasakti#configure terminal Bimasakti(config)#interface s1/0 Bimasakti(config-if)#ip address 167.205.44.1 255.255.255.192 Bimasakti(config-if)#no shutdown Bimasakti(config-if)#interface e2/0 Bimasakti(config-if)#ip address 192.168.1.3 255.255.255.0 Bimasakti(config-if)#no shutdown Bimasakti(config-if)#end !Check your configuration Bimasakti#show running-config

!Configure routing protocol with EIGRP Bimasakti#configure terminal Bimasakti(config)#router eigrp 1 Bimasakti(config-router)#network 10.1.0.0 0.0.255.255 Bimasakti(config-router)#network 167.205.44.0 0.0.0.63 Bimasakti(config-router)#no auto-summary Bimasakti(config-router)#end Bimasakti#

!Don't forget to check your configuration In my complete configuration is seem like this :

!

version 12.3

service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname Bimasakti ! boot-start-marker boot-end-marker ! ! no aaa new-model ip subnet-zero ! ! !

interface FastEthernet0/0 no ip address shutdown duplex auto speed auto ! interface FastEthernet0/1 no ip address shutdown duplex auto speed auto ! interface Serial1/0 ip address 167.205.44.1 255.255.255.192 serial restart-delay 0 ! interface Serial1/1 no ip address shutdown serial restart-delay 0 ! interface Serial1/2 no ip address shutdown serial restart-delay 0 ! interface Serial1/3 no ip address shutdown serial restart-delay 0 ! interface Ethernet2/0 ip address 192.168.1.3 255.255.255.0 half-duplex ! router eigrp 1 network 167.205.44.0 0.0.0.63 network 192.168.1.0 no auto-summary ! ip http server ip classless ! control-plane ! gatekeeper shutdown ! line con 0 logging synchronous line aux 0 line vty 0 4 login ! end  PC and Server

To configure your PC & Server, you can do it as generally how to set your computer IP. If you choose UNIX machine, may be we can use ifconfig command. But in this sample, I use a VPC (Virtual PC) as Server and PC. So, to configure the IP address shown at bellow :

e.x : #ip 10.0.1.5 10.0.1.1 /24

It is easy, isn't it ?! I wrote this article just to spent my time, and to review my knowledge. So, when I forget in the next time...I'll just to see this article. It's sounds silly but I enjoy with this ! Fiuhh...finally, I finish this job. Next chapter I want to discuss about OSPF & NAT configuration.