Lab 50 - EIGRP Filtering with Passive-Interface

Prerequisites: CCNP level skills.

Note!
Use the basic EIGRP configuration (Lab 45 Task 1) in the labs 45-53.

EIGRP filtering can use:

1. Standard ACL.
2. Extended ACL.
3. Prefix-List.
4. Route-Map.
5. Administrative Distance.
6. Passive-Interface.
7. Offset-List.
8. Stub Routing.
9. Selective Stub Routing (stub routing with leak map).

Topology

Pic. 1 - Topology Diagram.

Icons designed by: Andrzej Szoblik - http://www.newo.pl

Task 1

Configure R1 so that it receives prefixes on its S0/0 interface but not S0/1. Do not use any access-list, distribute-list or route-map, or distance command. R1 should still advertise 10.1.13.0/24.

Lab Solution

Task 1
Configure R1 so that it receives prefixes on its S0/0 interface but not S0/1. Do not use any access-list, distribute-list or route-map, or distance command. R1 should still advertise 10.1.13.0/24.

R1 Configuration:

!

router eigrp 1
 passive-interface Serial0/1
 network 10.1.13.1 0.0.0.0
 network 10.1.123.1 0.0.0.0
 network 10.1.124.1 0.0.0.0
 network 172.16.101.1 0.0.0.0
 no auto-summary

!

Notice!

The 'passive-interface' command prevents EIGRP (and OSPF) from sending the hello packets out this interface. As a result of that, there is no neighbor adjacency built on that interface and no EIGRP exchange occurs. However, the interface is still enabled for EIGRP and as such the IP address found on the interface (subnet/network) is still being advertised.

Pic. 2 - R1's EIGRP Interfaces.

Pic. 3 - R4's Routing Table.

Note!

In case there are many interfaces that should be 'passive' the 'passive-interface default' could be used with 'no passive-interface' option.