Administrative Distance, Access Lists, Route Manipulation, and IP Multicast - CCIE Routing and Switching Exam Certification Guide - page 486

EIGRP-IGRP Redistribution Figure 10-1

EIGRP 100
192.168.1.1/24

IGRP 100

192.168.100.1/24

192.168.2.0/24 192.168.101.1/24

Router A Router C

Router B

The configuration for the routers in Figure 10-1 is shown in Example 10-15.

Example 10-15 Configuration of Routers with EIGRP and IGRP Redistribution

hostname routerA hostname routerA

router eigrp 100
network 192.168.1.0
network 192.168.2.0

hostname routerB hostname routerB

router eigrp 100
network 192.168.2.0
!
router igrp 100
network 192.168.100.0

hostname routerC hostname routerC

router igrp 100
network 192.168.100.0
network 192.168.101.0

OSPF Redistribution
This section reviews several things that you need to remember when redistributing with OSPF.

When redistributing routes into OSPF, use the subnets keyword to permit subnetted routes to
be received. If you do not use the keyword, only the major network route is redistributed
without any sub-networks. In other words, OSPF performs automatic summarization.

By default, redistributed routes are classified as external Type 2 (E2) in OSPF. The metric-type
keyword changes the external route to an external Type 1 (E1). For more information on this
see Chapter 8, “IP Link-State Routing Protocols.”

In Figure 10-2, Router B is configured to perform mutual redistribution between EIGRP and
OSPF. In this example, route maps and access lists prevent routing loops. The subnets keyword