Step 2: Configure eigrp.

1. Enable EIGRP AS 100 for all interfaces on R1 and R2 using the commands. Do not enable EIGRP yet on R3. For your reference, these are the commands which can be used:

R1(config)# router eigrp 100

R1(config-router)# network 10.0.0.0

R2(config)# router eigrp 100

R2(config-router)# network 10.0.0.0

2. Use the debug ip routing and the debug ip eigrp 100 commands to watch EIGRP install the routes in the routing table when your routers become adjacent. (Note: The type of output you receive may vary depending upon the IOS.) You get output similar to the following.

R3# debug ip routing

IP routing debugging is on

R3# debug ip eigrp 100

R3# conf t

Enter configuration commands, one per line. End with CNTL/Z.

R3(config)# router eigrp 100

*Jun 22 11:06:09.315: RT: add router 2048, all protocols have local database

R3(config-router)# network 10.0.0.0

*Jun 22 11:06:18.591: %DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 10.1.103.1 (Serial0/0/0) is up: new adjacency

*Jun 22 11:06:18.591: %DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 10.1.203.2 (Serial0/0/1) is up: new adjacency

*Jun 22 11:06:19.055: RT: updating eigrp 10.1.102.0/29 (0x0) :

via 10.1.103.1 Se0/0/0 0 1048578

*Jun 22 11:06:19.055: RT: add 10.1.102.0/29 via 10.1.103.1, eigrp metric [90/41024000]

*Jun 22 11:06:19.055: RT: updating eigrp 10.1.1.0/30 (0x0) :

via 10.1.103.1 Se0/0/0

R3(config-router)#end 0 1048578

*Jun 22 11:06:19.055: RT: add 10.1.1.0/30 via 10.1.103.1, eigrp metric [90/40640000]

*Jun 22 11:06:19.055: RT: updating eigrp 10.1.1.4/30 (0x0) :

via 10.1.103.1 Se0/0/0 0 1048578

*Jun 22 11:06:19.055: RT: add 10.1.1.4/30 via 10.1.103.1, eigrp metric [90/40640000]

*Jun 22 11:06:19.055: RT: updating eigrp 10.1.1.8/30 (0x0) :

via 10.1.103.1 Se0/0/0 0 1048578

*Jun 22 11:06:19.055: RT: add 10.1.1.8/30 via 10.1.103.1, eigrp metric [90/40640000]

*Jun 22 11:06:19.059: RT: updating eigrp 10.1.2.0/30 (0x0) :

via 10.1.103.1 Se0/0/0 0 1048578

*Jun 22 11:06:19.059: RT: add 10.1.2.0/30 via 10.1.103.1, eigrp metric [90/41152000]

*Jun 22 11:06:19.059: RT: updating eigrp 10.1.2.4/30 (0x0) :

via 10.1.103.1 Se0/0/0 0 1048578

<output omitted>

R3#

R3(config-router)# end

R3#

R3#undebug all

All possible debugging has been turned off

R3#

Essentially, the EIGRP DUAL state machine has just computed the topology table for these routes and installed them in the routing table.

3. Check to see that these routes exist in the routing table with the show ip route command.

R3# show ip route

Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP

a - application route

+ - replicated route, % - next hop override

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 17 subnets, 3 masks

D 10.1.1.0/30 [90/40640000] via 10.1.103.1, 00:10:54, Serial0/0/0

D 10.1.1.4/30 [90/40640000] via 10.1.103.1, 00:10:54, Serial0/0/0

D 10.1.1.8/30 [90/40640000] via 10.1.103.1, 00:10:54, Serial0/0/0

D 10.1.2.0/30 [90/40640000] via 10.1.203.2, 00:10:54, Serial0/0/1

D 10.1.2.4/30 [90/40640000] via 10.1.203.2, 00:10:54, Serial0/0/1

D 10.1.2.8/30 [90/40640000] via 10.1.203.2, 00:10:54, Serial0/0/1

C 10.1.3.0/30 is directly connected, Loopback31

L 10.1.3.1/32 is directly connected, Loopback31

C 10.1.3.4/30 is directly connected, Loopback35

L 10.1.3.5/32 is directly connected, Loopback35

C 10.1.3.8/30 is directly connected, Loopback39

L 10.1.3.9/32 is directly connected, Loopback39

D 10.1.102.0/29 [90/41024000] via 10.1.203.2, 00:10:54, Serial0/0/1

[90/41024000] via 10.1.103.1, 00:10:54, Serial0/0/0

C 10.1.103.0/29 is directly connected, Serial0/0/0

L 10.1.103.3/32 is directly connected, Serial0/0/0

C 10.1.203.0/29 is directly connected, Serial0/0/1

L 10.1.203.3/32 is directly connected, Serial0/0/1

R3#

4. After you have full adjacency between the routers, ping all the remote loopbacks to ensure full connectivity.

You should receive ICMP echo replies for each address pinged.

5. Verify the EIGRP neighbor relationships with the show ip eigrp neighbors command.

R1# show ip eigrp neighbors

EIGRP-IPv4 Neighbors for AS(100)

H Address Interface Hold Uptime SRTT RTO Q Seq

(sec) (ms) Cnt Num

1 10.1.103.3 Se0/0/1 13 00:14:20 49 2340 0 6

0 10.1.102.2 Se0/0/0 10 00:29:14 37 2340 0 36

R1#

R2# show ip eigrp neighbors

EIGRP-IPv4 Neighbors for AS(100)

H Address Interface Hold Uptime SRTT RTO Q Seq

(sec) (ms) Cnt Num

1 10.1.203.3 Se0/0/1 13 00:14:28 71 2340 0 7

0 10.1.102.1 Se0/0/0 13 00:29:21 35 2340 0 36

R2#

R3# show ip eigrp neighbors

EIGRP-IPv4 Neighbors for AS(100)

H Address Interface Hold Uptime SRTT RTO Q Seq

(sec) (ms) Cnt Num

1 10.1.203.2 Se0/0/1 13 00:14:07 1305 5000 0 37

0 10.1.103.1 Se0/0/0 14 00:14:07 42 2340 0 37

R3#