Lab 22: EIGRP Route Redistribution, Summarization, and Stub Routing-Part I

Configuring EIGRP

Configuring basic EIGRP is, for the most part, identical to configuring IGRP. Configuring EIGRP calls for the definition of an autonomous system (AS). By definition, an AS is a set of routers under a single administrative technical authority. Like IGRP, EIGRP uses the concept of ASs to separate routing processes. Having a registered AS when configuring EIGRP is not required.

This following three-step process can be used to configure EIGRP. The third step is optional to specific environments.

Step 1. Enable EIGRP and define an AS on the router. This is accomplished with the router eigrp autonomous_system_id global command.

Step 2. Add the networks that you want to run EIGRP on. This is accomplished with the network a.b.c.d from the config-router# mode. When you enter the network statements, it is necessary to enter only the major class boundary. In Cisco IOS Software Release 12.0 and later, the network command adds an additional wildcard mask, much like OSPF. This is an inverse bit mask ”for example, to enable EIGRP on network 172.16.1.0 only, the syntax would be network 172.16.1.0 0.0.0.255; however, note that EIGRP is smart enough to convert a subnet mask to a wildcard mask if you make a mistake. Now that's user -friendly!

Step 3. (Optional) Fine-tune EIGRP metrics with bandwidth statements, or configure IGRP summarization and options. By taking the time to configure bandwidth, EIGRP will have a more accurate picture of the network and also will aid in preventing EIGRP from saturating the link with broadcasts. The bandwidth always should be set on Frame Relay networks. The bandwidth can be changed with the bandwidth kilobits interface command. Later sections in the chapter cover bandwidth and summarizing EIGRP in greater detail.

Example 11-7 illustrates the EIGRP configuration from Figure 11-5 on the grinch router.

Example 11-7 EIGRP Configuration

 ! hostname grinch ! interface Ethernet1  ip address 172.16.2.1 255.255.255.0  media-type 10BaseT ! interface Serial0  no ip address  encapsulation frame-relay  no ip mroute-cache ! interface Serial0.1 multipoint  ip address 172.16.1.1 255.255.255.0  no ip split-horizon eigrp 2001  Split Horizons disabled   bandwidth 112  Bandwidth set to the sum of the remote PVCs  frame-relay map ip 172.16.1.5 110 broadcast  frame-relay map ip 172.16.1.6 130 broadcast !  router eigrp 2001  EIGRP routing process   network 172.16.0.0  Networks running EIGRP  ! 

Before further discussing these and other EIGRP options in greater detail, lets take a closer look at the show commands for EIGRP.