Sunday, March 13, 2011

Lab 38 - EIGRP NBMA Network

Prerequisites: CCNP level skills.

Topology
 Pic. 1 - EIGRP NBMA Topology.
Icons designed by: Andrzej Szoblik - http://www.newo.pl

Task 1
Enable EIGRP on all interfaces of the routers in pic. 1 (AS=1). Use the most specific wildcard mask. Disable automatic summarization. Make the local loopback0 IP address the ID of EIGRP router.

Task 2
Check the reachability between the spoke routers (R2 and R3). Make sure LANs between R2 and R3 are reachable.

Lab Solution

Task 1
Enable EIGRP on all interfaces of the routers in pic. 1 (AS=1). Use the most specific wildcard mask. Disable automatic summarization. Make the local loopback0 IP address the ID of EIGRP router.

R1 Configuration:
!
router eigrp 1
 network 10.1.0.1 0.0.0.0
 network 10.1.1.1 0.0.0.0
 network 172.16.101.1 0.0.0.0
 no auto-summary
 eigrp router-id 172.16.101.1
!

R2 Configuration:
!
router eigrp 1
 network 10.1.0.2 0.0.0.0
 network 10.1.2.2 0.0.0.0
 network 172.16.102.2 0.0.0.0
 no auto-summary
 eigrp router-id 172.16.102.2
!

R3 Configuration:
!
router eigrp 1
 network 10.1.0.3 0.0.0.0
 network 10.1.3.3 0.0.0.0
 network 172.16.103.3 0.0.0.0
 no auto-summary
 eigrp router-id 172.16.103.3
!

Verification:
Pic. 2 - EIGRP Neighbors on R1.

Note!
'Q Cnt' show '0' for each neighbor. This indicates full convergence.

Pic. 3 - R2's EIGRP Routing Table.

Note!
R2 does NOT receive prefixes advertised by R3. The reason is the 'split-horizon' enabled on R1 by default. The solution to this reachability problem on NBMA hub-and-spoke topology can be disabling 'split-horizon' or using sub-interfaces point-to-point with different layer 3 subnet address on each.

Task 2
Check the reachability between the spoke routers (R2 and R3). Make sure LANs between R2 and R3 are reachable.

R1 Configuration:
!
interface Serial0/0
 ip address 10.1.0.1 255.255.255.0
 encapsulation frame-relay
 no ip split-horizon eigrp 1
 serial restart-delay 0
 frame-relay map ip 10.1.0.2 102 broadcast
 frame-relay map ip 10.1.0.3 103 broadcast
 no frame-relay inverse-arp
!

Verification:
Pic. 4 - R2's EIGRP Routing Table.

Pic. 5 - Ping Test Between Spokes.