For the above topology the configuration is rather simple. In order for the routers to form neighbor relationships they must have the same EIGRP process id:
R1 config:
interface FastEthernet0/0 ip address 10.1.1.1 255.255.255.0 duplex half ! interface GigabitEthernet4/0 ip address 10.0.0.1 255.255.255.0 negotiation auto ! router eigrp 1 network 10.0.0.0 0.0.0.255 network 10.1.1.0 0.0.0.255 auto-summary !
R2 config:
interface GigabitEthernet4/0 ip address 10.0.0.2 255.255.255.0 negotiation auto ! interface GigabitEthernet5/0 ip address 10.2.2.2 255.255.255.0 negotiation auto ! interface GigabitEthernet6/0 no ip address shutdown negotiation auto ! router eigrp 1 network 10.0.0.0 0.0.0.255 network 10.2.2.0 0.0.0.255 auto-summary !
R3 config:
interface FastEthernet0/0 ip address 10.1.1.3 255.255.255.0 duplex half ! interface GigabitEthernet4/0 ip address 10.2.2.3 255.255.255.0 negotiation auto ! router eigrp 1 network 10.1.1.0 0.0.0.255 network 10.2.2.0 0.0.0.255 auto-summary !
Troubleshooting EIGRP is rather simple use the following commands:
R1#show ip eigrp neighbors IP-EIGRP neighbors for process 1 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 1 10.1.1.3 Fa0/0 12 00:00:34 37 222 0 10 0 10.0.0.2 Gi4/0 14 00:04:59 15 300 0 8 R1#show ip eigrp ? <1-65535> Autonomous System accounting IP-EIGRP Accounting interfaces IP-EIGRP interfaces neighbors IP-EIGRP neighbors topology IP-EIGRP Topology Table traffic IP-EIGRP Traffic Statistics vrf Select a VPN Routing/Forwarding instance R1#show ip eigrp interfaces IP-EIGRP interfaces for process 1 Xmit Queue Mean Pacing Time Multicast Pending Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes Gi4/0 1 0/0 15 0/1 50 0 Fa0/0 1 0/0 37 0/1 50 0 R1#show ip eigrp topology IP-EIGRP Topology Table for AS(1)/ID(10.1.1.1) Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status P 10.2.2.0/24, 1 successors, FD is 3072 via 10.0.0.2 (3072/2816), GigabitEthernet4/0 via 10.1.1.3 (28416/2816), FastEthernet0/0 P 10.1.1.0/24, 1 successors, FD is 28160 via Connected, FastEthernet0/0 P 10.0.0.0/24, 1 successors, FD is 2816 via Connected, GigabitEthernet4/0 R1#show ip route Codes: 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 Gateway of last resort is not set 10.0.0.0/24 is subnetted, 3 subnets D 10.2.2.0 [90/3072] via 10.0.0.2, 00:00:41, GigabitEthernet4/0 C 10.1.1.0 is directly connected, FastEthernet0/0 C 10.0.0.0 is directly connected, GigabitEthernet4/0
Missing routes in the routing table may indicate a failed relationship or missing “network” commands in the EIGRP configuration.
The debug commands are helpful for troubleshooting neighbor relationships:
R3#debug ip eigrp IP-EIGRP Route Events debugging is on R3#debug ip eigrp nei R3#debug ip eigrp neighbor 1 10.1.1.1 IP Neighbor target enabled on AS 1 for 10.1.1.1 IP-EIGRP Neighbor Target Events debugging is on R3#conf t Enter configuration commands, one per line. End with CNTL/Z. R3(config)#int g4/0 R3(config-if)#shutdown *Apr 8 17:42:34.219: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 10.2.2.2 (GigabitEthernet4/0) is down: interface down *Apr 8 17:42:34.223: IP-EIGRP(Default-IP-Routing-Table:1): route installed for 10.0.0.0 () *Apr 8 17:42:34.247: IP-EIGRP(Default-IP-Routing-Table:1): 10.2.2.0/24 - not in IP routing table *Apr 8 17:42:34.247: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.2.2.0/24 metric 4294967295 - 0 4294967295 *Apr 8 17:42:34.283: IP-EIGRP(Default-IP-Routing-Table:1): Processing incoming REPLY packet *Apr 8 17:42:34.283: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.2.2.0/24 M 28672 - 25600 3072 SM 3072 - 2560 512 *Apr 8 17:42:34.287: IP-EIGRP(Default-IP-Routing-Table:1): route installed for 10.2.2.0 () R3(config-if)#no shutdown *Apr 8 17:42:36.163: %LINK-5-CHANGED: Interface GigabitEthernet4/0, changed state to administratively down *Apr 8 17:42:36.327: IP-EIGRP(Default-IP-Routing-Table:1): 10.2.2.0/24 - do advertise out FastEthernet0/0 *Apr 8 17:42:36.327: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.2.2.0/24 metric 4294967295 - 25600 4294967295 *Apr 8 17:42:36.387: IP-EIGRP(Default-IP-Routing-Table:1): Processing incoming REPLY packet *Apr 8 17:42:36.387: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.2.2.0/24 M 28672 - 25600 3072 SM 3072 - 2560 512 *Apr 8 17:42:36.387: IP-EIGRP(Default-IP-Routing-Table:1): 10.2.2.0/24 routing table not updated thru 10.1.1.1 *Apr 8 17:42:36.403: IP-EIGRP(Default-IP-Routing-Table:1): 10.2.2.0/24 - do advertise out FastEthernet0/0 *Apr 8 17:42:36.403: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.2.2.0/24 metric 2816 - 2560 256 *Apr 8 17:42:37.159: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 10.2.2.2 (GigabitEthernet4/0) is up: new adjacency *Apr 8 17:42:37.179: IP-EIGRP(Default-IP-Routing-Table:1): 10.1.1.0/24 - do advertise out GigabitEthernet4/0 *Apr 8 17:42:37.179: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.1.0/24 metric 28160 - 25600 2560 *Apr 8 17:42:37.183: IP-EIGRP(Default-IP-Routing-Table:1): 10.0.0.0/24 - do advertise out GigabitEthernet4/0 *Apr 8 17:42:37.183: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.0.0.0/24 metric 28416 - 25600 2816 *Apr 8 17:42:37.183: IP-EIGRP(Default-IP-Routing-Table:1): 10.2.2.0/24 - do advertise out GigabitEthernet4/0 *Apr 8 17:42:38.267: %LINK-3-UPDOWN: Interface GigabitEthernet4/0, changed state to up *Apr 8 17:42:42.011: IP-EIGRP(Default-IP-Routing-Table:1): Processing incoming UPDATE packet *Apr 8 17:42:42.215: IP-EIGRP(Default-IP-Routing-Table:1): Processing incoming UPDATE packet *Apr 8 17:42:42.215: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.0.0.0/24 M 3072 - 2560 512 SM 2816 - 2560 256 *Apr 8 17:42:42.219: IP-EIGRP(Default-IP-Routing-Table:1): route installed for 10.0.0.0 () *Apr 8 17:42:42.219: IP-EIGRP(Default-IP-Routing-Table:1): route installed for 10.0.0.0 () *Apr 8 17:42:42.219: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.1.0/24 M 28672 - 25600 3072 SM 28416 - 25600 2816 *Apr 8 17:42:42.219: IP-EIGRP(Default-IP-Routing-Table:1): 10.1.1.0/24 routing table not updated thru 10.2.2.2 *Apr 8 17:42:42.219: IP-EIGRP(Default-IP-Routing-Table:1): 10.1.1.0/24 - do advertise out GigabitEthernet4/0 *Apr 8 17:42:42.219: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.1.0/24 metric 28160 - 25600 2560 *Apr 8 17:42:42.219: IP-EIGRP(Default-IP-Routing-Table:1): 10.2.2.0/24 - do advertise out GigabitEthernet4/0 *Apr 8 17:42:42.227: IP-EIGRP(Default-IP-Routing-Table:1): Processing incoming UPDATE packet *Apr 8 17:42:42.227: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.0.0.0/24 M 3072 - 2560 512 SM 2816 - 2560 256 *Apr 8 17:42:42.227: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.1.0/24 M 28672 - 25600 3072 SM 28416 - 25600 2816 *Apr 8 17:42:42.231: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.0.0.0/24 metric 3072 - 2560 512 *Apr 8 17:42:42.235: IP-EIGRP(Default-IP-Routing-Table:1): Processing incoming UPDATE packet *Apr 8 17:42:42.235: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.1.0/24 M 4294967295 - 25600 4294967295 SM 4294967295 - 25600 4294967295 *Apr 8 17:42:42.235: IP-EIGRP(Default-IP-Routing-Table:1): 10.0.0.0/24 - do advertise out FastEthernet0/0 *Apr 8 17:42:42.239: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.0.0.0/24 metric 3072 - 2560 512 *Apr 8 17:42:42.247: IP-EIGRP(Default-IP-Routing-Table:1): 10.1.1.0/24 #- do advertise out GigabitEthernet4/0 *Apr 8 17:42:42.247: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.1.0/24 metric 28160 - 25600 2560 *Apr 8 17:42:42.247: IP-EIGRP(Default-IP-Routing-Table:1): 10.2.2.0/24 - do advertise out GigabitEthernet4/0