Lab 53 - EIGRP Filtering with Stub Routing and Leak Map

Prerequisites: CCNP level skills.

Note!
Use the configuration from the lab 52 but REMOVE 'eigrp stub' on R4.

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

Using the lab 52 config, remove eigrp stub command on R4.

Task 2
Configure R1 and R2 as EIGRP stub routers. Use default options (connected and summary).

Task 3
Keeping R1 and R2 EIGRP stub routers allow R1 to advertise 10.0.44.0/24.

Task 4
Keeping R1 and R2 EIGRP stub routers allow R2 to advertise 10.0.4.0/24.

Lab Solution

Task 1
Using the lab 52 config, remove eigrp stub command on R4.

R4 Configuration:

!

R4(config-router)#no eigrp stub
R4(config-router)#

!

Task 2

Configure R1 and R2 as EIGRP stub routers. Use default options (connected and summary).

R1 Configuration:

!

router eigrp 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
 eigrp stub connected summary

!

R2 Configuration:

!

router eigrp 1
 network 10.1.123.2 0.0.0.0
 network 10.1.124.2 0.0.0.0
 network 172.16.102.2 0.0.0.0
 no auto-summary
 eigrp stub connected summary

!

Verification:

Pic. 2 - R3 Routing Table.

Notice!
R3 does not receive R4's prefixes because R1 and R2 filters them out (only connected and summary routes can be advertised by R1 and R2).

Task 3

Keeping R1 and R2 EIGRP stub routers allow R1 to advertise 10.0.44.0/24.

R1 Configuration:

!

ip prefix-list R4_L3 seq 5 permit 10.0.44.0/24
!

route-map LEAK permit 10
 match ip address prefix-list R4_L3
!

router eigrp 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
 eigrp stub connected summary leak-map LEAK

!

Verification:

Pic. 3 - R3's Routing Table.

Notice!
R1 unsuppressed 10.0.44.0/24. It takes a moment longer to advertise the same prefix over S0/0 as it is a slow link. Also, while using 'leak-map' the defaults (connected and summary) are not added unless manually typed in.

Task 4

Keeping R1 and R2 EIGRP stub routers allow R2 to advertise 10.0.4.0/24.

R2 Configuration:

!

ip prefix-list R4_L2 seq 5 permit 10.0.4.0/24
!

route-map LEAK permit 10
 match ip address prefix-list R4_L2
!

router eigrp 1
 network 10.1.123.2 0.0.0.0
 network 10.1.124.2 0.0.0.0
 network 172.16.102.2 0.0.0.0
 no auto-summary
 eigrp stub connected summary leak-map LEAK

!

Verification:

Pic. 4 - R3's Routing Table.