Redistribution Between Two EIGRP Autonomous Systems
R1:
R1(config)#router eigrp 200 R1(config-router)#network 172.16.1.0 0.0.0.255 R1(config-router)#exit R1(config)# *Mar 1 00:11:35.211: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 200: Neighbor 172.16.1.21 (FastEthernet0/0) is up: new adjacency
R2:
R2(config)#router eigrp 200 R2(config-router)#network 172.16.1.0 0.0.0.255 R2(config-router)# *Mar 1 00:08:09.211: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 200: Neighbor 172.16.1.12 (FastEthernet0/0) is up: new adjacency R2(config-router)# R2(config-router)#exit R2(config)#router eigrp 100 R2(config-router)#network 10.1.0.0 0.0.255.255 R2(config-router)#exit R2(config)# *Mar 1 00:09:10.095: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 10.1.1.32 (FastEthernet0/1) is up: new adjacency
R3:
R3(config)#router eigrp 100 R3(config-router)#network 10.1.0.0 0.0.255.255 R3(config-router)#exit R3(config)# *Mar 1 00:09:05.391: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 10.1.1.23 (FastEthernet0/0) is up: new adjacency
Check the routing tables:
R1:
R1#sh 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 172.16.0.0/24 is subnetted, 1 subnets C 172.16.1.0 is directly connected, FastEthernet0/0 R1#
R2:
R2#sh 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 172.16.0.0/24 is subnetted, 1 subnets C 172.16.1.0 is directly connected, FastEthernet0/0 10.0.0.0/24 is subnetted, 2 subnets D 10.1.2.0 [90/307200] via 10.1.1.32, 00:02:42, FastEthernet0/1 C 10.1.1.0 is directly connected, FastEthernet0/1 R2#
R3:
R3#sh 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, 2 subnets C 10.1.2.0 is directly connected, FastEthernet0/1 C 10.1.1.0 is directly connected, FastEthernet0/0 R3#
Now redistribute eigrp 100 into 200:
R2:
R2: R2(config)#router eigrp 200 R2(config-router)#redistribute eigrp 100 route-map TO_EIGRP200 R2(config)#route-map TO_EIGRP200 deny 10 R2(config-route-map)# match tag 200 R2(config-route-map)#exit R2(config)#route-map TO_EIGRP200 permit 20 R2(config-route-map)#set tag 100
Check the routes on R1 to see if there are any for 10.1.2.0 and 10.1.1.0:
R1:
R1: R1#sh 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 172.16.0.0/24 is subnetted, 1 subnets C 172.16.1.0 is directly connected, FastEthernet0/0 10.0.0.0/24 is subnetted, 2 subnets D EX 10.1.2.0 [170/332800] via 172.16.1.21, 00:00:17, FastEthernet0/0 D EX 10.1.1.0 [170/307200] via 172.16.1.21, 00:00:17, FastEthernet0/0 R1#
Try to ping R3′s int Fa0/1 (10.1.2.3) from R1:
R1:
R1#ping 10.1.2.3 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.1.2.3, timeout is 2 seconds: ..... Success rate is 0 percent (0/5) R1#
It fails because there are routes to come back. We need redistribute 200 into 100:
R2:
R2(config)#router eigrp 100 R2(config-router)#redistribute eigrp 200 route-map TO_EIGRP100 R2(config-router)#exit R2(config)#route-map TO_EIGRP100 deny 10 R2(config-route-map)#match tag 100 R2(config-route-map)#exit R2(config)#route-map TO_EIGRP100 permit 20 R2(config-route-map)#set tag 200
On R3 there should be a route for 172.16.1.0/24:
R3:
R3#sh 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 172.16.0.0/24 is subnetted, 1 subnets D EX 172.16.1.0 [170/307200] via 10.1.1.23, 00:02:27, FastEthernet0/0 10.0.0.0/24 is subnetted, 2 subnets C 10.1.2.0 is directly connected, FastEthernet0/1 C 10.1.1.0 is directly connected, FastEthernet0/0 R3#
Now go back to R1 and try to ping 10.1.2.3:
R1:
R1#ping 10.1.2.3 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.1.2.3, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 12/53/156 ms
[success]
Summary:
R3 is advertising the network 10.1.2.0/24 to R2 through AS 100; R2 is redistributing this route into AS 200 and advertising it to R1.
[/success]
[error]
The routes from EIGRP 100 are tagged 100 before redistributing them to EIGRP 200. When routes from EIGRP 200 are redistributed back to EIGRP 100, the routes with 100 tags are denied to ensure a loop-free topology.
[/error]