This example focuses on eliminating any type of asymmetric routing on both the hub and spoke side. The same variations can be defined on either the hub or the spoke. The first variation is modifying the delay on the tunnel since EIGRP uses delay this directly. This will affect both the switches, SW3 and SW4 on the hub side to point traffic to IOS22, which effectively makes CSR9 a backup hub. Since we have just a single cloud or subnet, spoke side modifications are very limited.
Hub Side - SW3
SW3#sh 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 10.3.22.22 to network 0.0.0.0
D*EX 0.0.0.0/0 [170/26880768] via 10.3.22.22, 1d09h, Vlan322
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback0
10.0.0.0/8 is variably subnetted, 24 subnets, 2 masks
D 10.1.1.0/24 [90/26880256] via 10.3.22.22, 22:03:05, Vlan322
[90/26880256] via 10.3.9.9, 22:03:05, Vlan39
C 10.1.3.0/24 is directly connected, Vlan31
L 10.1.3.3/32 is directly connected, Vlan31
C 10.2.3.0/24 is directly connected, Vlan32
L 10.2.3.3/32 is directly connected, Vlan32
C 10.3.6.0/24 is directly connected, Vlan36
L 10.3.6.3/32 is directly connected, Vlan36
C 10.3.9.0/24 is directly connected, Vlan39
L 10.3.9.3/32 is directly connected, Vlan39
C 10.3.13.0/24 is directly connected, Vlan313
L 10.3.13.3/32 is directly connected, Vlan313
C 10.3.14.0/24 is directly connected, Vlan314
L 10.3.14.3/32 is directly connected, Vlan314
C 10.3.22.0/24 is directly connected, Vlan322
L 10.3.22.3/32 is directly connected, Vlan322
C 10.3.23.0/24 is directly connected, Vlan323
L 10.3.23.3/32 is directly connected, Vlan323
D 10.4.9.0/24 [90/3072] via 172.16.101.4, 3d16h, Vlan101
[90/3072] via 10.3.9.9, 3d16h, Vlan39
D 10.4.22.0/24 [90/3072] via 172.16.101.4, 3d16h, Vlan101
[90/3072] via 10.3.22.22, 3d16h, Vlan322
D 10.11.19.0/24 [90/26880512] via 10.3.22.22, 22:00:53, Vlan322
[90/26880512] via 10.3.9.9, 22:00:53, Vlan39
D EX 10.102.12.0/24 [170/26880768] via 10.3.22.22, 22:01:24, Vlan322
[170/26880768] via 10.3.9.9, 22:01:24, Vlan39
D EX 10.102.15.0/24 [170/26880768] via 10.3.22.22, 22:01:24, Vlan322
[170/26880768] via 10.3.9.9, 22:01:24, Vlan39
D EX 10.102.25.0/24 [170/26880512] via 10.3.22.22, 22:01:24, Vlan322
[170/26880512] via 10.3.9.9, 22:01:24, Vlan39
D EX 10.255.10.0/24 [170/26880768] via 10.3.22.22, 21:59:54, Vlan322
[170/26880768] via 10.3.9.9, 21:59:54, Vlan39
19.0.0.0/32 is subnetted, 1 subnets
D 19.19.19.19 [90/27008512] via 10.3.22.22, 22:00:53, Vlan322
[90/27008512] via 10.3.9.9, 22:00:53, Vlan39
20.0.0.0/32 is subnetted, 1 subnets
D EX 20.20.20.20 [170/27008512] via 10.3.22.22, 22:01:24, Vlan322
[170/27008512] via 10.3.9.9, 22:01:24, Vlan39
22.0.0.0/32 is subnetted, 1 subnets
D 22.22.22.22 [90/130816] via 10.3.22.22, 4d02h, Vlan322
24.0.0.0/32 is subnetted, 1 subnets
D 24.24.24.24 [90/27008512] via 10.3.22.22, 21:59:54, Vlan322
[90/27008512] via 10.3.9.9, 21:59:54, Vlan39
33.0.0.0/32 is subnetted, 1 subnets
D 33.33.33.33 [90/27008256] via 10.3.22.22, 21:59:54, Vlan322
[90/27008256] via 10.3.9.9, 21:59:54, Vlan39
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
C 172.16.101.0/24 is directly connected, Vlan101
L 172.16.101.3/32 is directly connected, Vlan101
D 172.16.103.0/24 [90/26880512] via 10.3.22.22, 21:59:54, Vlan322
[90/26880512] via 10.3.9.9, 21:59:54, Vlan39
Hub Side - SW4
SW4#sh 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 10.4.22.22 to network 0.0.0.0
D*EX 0.0.0.0/0 [170/26880768] via 10.4.22.22, 1d09h, Vlan422
4.0.0.0/32 is subnetted, 1 subnets
C 4.4.4.4 is directly connected, Loopback0
10.0.0.0/8 is variably subnetted, 24 subnets, 2 masks
D 10.1.1.0/24 [90/26880256] via 10.4.22.22, 21:45:04, Vlan422
[90/26880256] via 10.4.9.9, 21:45:04, Vlan49
C 10.1.4.0/24 is directly connected, Vlan41
L 10.1.4.4/32 is directly connected, Vlan41
C 10.2.4.0/24 is directly connected, Vlan42
L 10.2.4.4/32 is directly connected, Vlan42
D 10.3.9.0/24 [90/3072] via 172.16.101.3, 3d15h, Vlan101
[90/3072] via 10.4.9.9, 3d15h, Vlan49
D 10.3.22.0/24 [90/3072] via 172.16.101.3, 3d15h, Vlan101
[90/3072] via 10.4.22.22, 3d15h, Vlan422
C 10.4.6.0/24 is directly connected, Vlan46
L 10.4.6.4/32 is directly connected, Vlan46
C 10.4.9.0/24 is directly connected, Vlan49
L 10.4.9.4/32 is directly connected, Vlan49
C 10.4.13.0/24 is directly connected, Vlan413
L 10.4.13.4/32 is directly connected, Vlan413
C 10.4.14.0/24 is directly connected, Vlan414
L 10.4.14.4/32 is directly connected, Vlan414
C 10.4.22.0/24 is directly connected, Vlan422
L 10.4.22.4/32 is directly connected, Vlan422
C 10.4.23.0/24 is directly connected, Vlan423
L 10.4.23.4/32 is directly connected, Vlan423
D 10.11.19.0/24 [90/26880512] via 10.4.22.22, 21:42:54, Vlan422
[90/26880512] via 10.4.9.9, 21:42:54, Vlan49
D EX 10.102.12.0/24 [170/26880768] via 10.4.22.22, 21:43:24, Vlan422
[170/26880768] via 10.4.9.9, 21:43:24, Vlan49
D EX 10.102.15.0/24 [170/26880768] via 10.4.22.22, 21:43:24, Vlan422
[170/26880768] via 10.4.9.9, 21:43:24, Vlan49
D EX 10.102.25.0/24 [170/26880512] via 10.4.22.22, 21:43:24, Vlan422
[170/26880512] via 10.4.9.9, 21:43:24, Vlan49
D EX 10.255.10.0/24 [170/26880768] via 10.4.22.22, 21:41:56, Vlan422
[170/26880768] via 10.4.9.9, 21:41:56, Vlan49
19.0.0.0/32 is subnetted, 1 subnets
D 19.19.19.19 [90/27008512] via 10.4.22.22, 21:42:54, Vlan422
[90/27008512] via 10.4.9.9, 21:42:54, Vlan49
20.0.0.0/32 is subnetted, 1 subnets
D EX 20.20.20.20 [170/27008512] via 10.4.22.22, 21:43:24, Vlan422
[170/27008512] via 10.4.9.9, 21:43:24, Vlan49
22.0.0.0/32 is subnetted, 1 subnets
D 22.22.22.22 [90/130816] via 10.4.22.22, 3d15h, Vlan422
24.0.0.0/32 is subnetted, 1 subnets
D 24.24.24.24 [90/27008512] via 10.4.22.22, 21:41:56, Vlan422
[90/27008512] via 10.4.9.9, 21:41:56, Vlan49
33.0.0.0/32 is subnetted, 1 subnets
D 33.33.33.33 [90/27008256] via 10.4.22.22, 21:41:56, Vlan422
[90/27008256] via 10.4.9.9, 21:41:56, Vlan49
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
C 172.16.101.0/24 is directly connected, Vlan101
L 172.16.101.4/32 is directly connected, Vlan101
D 172.16.103.0/24 [90/26880512] via 10.4.22.22, 21:41:56, Vlan422
[90/26880512] via 10.4.9.9, 21:41:56, Vlan49
IOS33#sh ip route eigrp
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, p - overrides from PfR
Gateway of last resort is 172.16.103.24 to network 0.0.0.0
D*EX 0.0.0.0/0 [170/3072] via 172.16.103.24, 1d12h, GigabitEthernet0/0
10.0.0.0/8 is variably subnetted, 11 subnets, 2 masks
D 10.3.9.0/24 [90/26880256] via 10.1.1.9, 1d00h, Tunnel1
D 10.3.22.0/24 [90/26880256] via 10.1.1.22, 1d00h, Tunnel1
D 10.4.9.0/24 [90/26880256] via 10.1.1.9, 1d00h, Tunnel1
D 10.4.22.0/24 [90/26880256] via 10.1.1.22, 1d00h, Tunnel1
D 10.11.19.0/24 [90/28160256] via 10.1.1.22, 1d00h, Tunnel1
[90/28160256] via 10.1.1.9, 1d00h, Tunnel1
D EX 10.102.12.0/24 [170/28160512] via 10.1.1.22, 1d00h, Tunnel1
[170/28160512] via 10.1.1.9, 1d00h, Tunnel1
D EX 10.102.15.0/24 [170/28160512] via 10.1.1.22, 1d00h, Tunnel1
[170/28160512] via 10.1.1.9, 1d00h, Tunnel1
D EX 10.102.25.0/24 [170/28160256] via 10.1.1.22, 1d00h, Tunnel1
[170/28160256] via 10.1.1.9, 1d00h, Tunnel1
D EX 10.255.10.0/24
[170/3072] via 172.16.103.24, 1d00h, GigabitEthernet0/0
19.0.0.0/32 is subnetted, 1 subnets
D 19.19.19.19 [90/28288256] via 10.1.1.22, 1d00h, Tunnel1
[90/28288256] via 10.1.1.9, 1d00h, Tunnel1
20.0.0.0/32 is subnetted, 1 subnets
D EX 20.20.20.20 [170/28288256] via 10.1.1.22, 1d00h, Tunnel1
[170/28288256] via 10.1.1.9, 1d00h, Tunnel1
22.0.0.0/32 is subnetted, 1 subnets
D 22.22.22.22 [90/27008000] via 10.1.1.22, 1d00h, Tunnel1
24.0.0.0/32 is subnetted, 1 subnets
D 24.24.24.24 [90/130816] via 172.16.103.24, 1d00h, GigabitEthernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
D 172.16.101.0/24 [90/26880512] via 10.1.1.22, 1d00h, Tunnel1
[90/26880512] via 10.1.1.9, 1d00h, Tunnel1
We see that the routing table has not been modified yet.
CSR9
interface Tunnel1
delay 10000
CSR9#show int tun1
Tunnel1 is up, line protocol is up
Hardware is Tunnel
Internet address is 10.1.1.9/24
MTU 9972 bytes, BW 100 Kbit/sec, DLY 100000 usec,
The normal, default is 50000 microseconds, which is what IOS22 is set to.
IOS22#sh int tun1
Tunnel1 is up, line protocol is up
Hardware is Tunnel
Internet address is 10.1.1.22/24
MTU 17912 bytes, BW 100 Kbit/sec, DLY 50000 usec,
We modify the tunnel interface on CSR9 to 10000 which puts 100,000 mircoseconds of delay on the tunnel, make it effective on the switches behind CSR9 and the spokes to prefer the IOS22 hub.
SW3#sh ip route eigrp
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 10.3.22.22 to network 0.0.0.0
D*EX 0.0.0.0/0 [170/26880768] via 10.3.22.22, 1d09h, Vlan322
10.0.0.0/8 is variably subnetted, 24 subnets, 2 masks
D 10.1.1.0/24 [90/26880256] via 10.3.22.22, 00:09:42, Vlan322
D 10.4.9.0/24 [90/3072] via 172.16.101.4, 3d16h, Vlan101
[90/3072] via 10.3.9.9, 3d16h, Vlan39
D 10.4.22.0/24 [90/3072] via 172.16.101.4, 3d16h, Vlan101
[90/3072] via 10.3.22.22, 3d16h, Vlan322
D 10.11.19.0/24 [90/26880512] via 10.3.22.22, 00:09:46, Vlan322
D EX 10.102.12.0/24 [170/26880768] via 10.3.22.22, 00:09:46, Vlan322
D EX 10.102.15.0/24 [170/26880768] via 10.3.22.22, 00:09:46, Vlan322
D EX 10.102.25.0/24 [170/26880512] via 10.3.22.22, 00:09:46, Vlan322
D EX 10.255.10.0/24 [170/26880768] via 10.3.22.22, 00:09:46, Vlan322
19.0.0.0/32 is subnetted, 1 subnets
D 19.19.19.19 [90/27008512] via 10.3.22.22, 00:09:46, Vlan322
20.0.0.0/32 is subnetted, 1 subnets
D EX 20.20.20.20 [170/27008512] via 10.3.22.22, 00:09:46, Vlan322
22.0.0.0/32 is subnetted, 1 subnets
D 22.22.22.22 [90/130816] via 10.3.22.22, 4d02h, Vlan322
24.0.0.0/32 is subnetted, 1 subnets
D 24.24.24.24 [90/27008512] via 10.3.22.22, 00:09:46, Vlan322
33.0.0.0/32 is subnetted, 1 subnets
D 33.33.33.33 [90/27008256] via 10.3.22.22, 00:09:46, Vlan322
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
D 172.16.103.0/24 [90/26880512] via 10.3.22.22, 00:09:46, Vlan322
SW4#sh ip route eigrp
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 10.4.22.22 to network 0.0.0.0
D*EX 0.0.0.0/0 [170/26880768] via 10.4.22.22, 1d09h, Vlan422
10.0.0.0/8 is variably subnetted, 24 subnets, 2 masks
D 10.1.1.0/24 [90/26880256] via 10.4.22.22, 00:10:17, Vlan422
D 10.3.9.0/24 [90/3072] via 172.16.101.3, 3d15h, Vlan101
[90/3072] via 10.4.9.9, 3d15h, Vlan49
D 10.3.22.0/24 [90/3072] via 172.16.101.3, 3d15h, Vlan101
[90/3072] via 10.4.22.22, 3d15h, Vlan422
D 10.11.19.0/24 [90/26880512] via 10.4.22.22, 00:10:21, Vlan422
D EX 10.102.12.0/24 [170/26880768] via 10.4.22.22, 00:10:21, Vlan422
D EX 10.102.15.0/24 [170/26880768] via 10.4.22.22, 00:10:21, Vlan422
D EX 10.102.25.0/24 [170/26880512] via 10.4.22.22, 00:10:21, Vlan422
D EX 10.255.10.0/24 [170/26880768] via 10.4.22.22, 00:10:21, Vlan422
19.0.0.0/32 is subnetted, 1 subnets
D 19.19.19.19 [90/27008512] via 10.4.22.22, 00:10:21, Vlan422
20.0.0.0/32 is subnetted, 1 subnets
D EX 20.20.20.20 [170/27008512] via 10.4.22.22, 00:10:21, Vlan422
22.0.0.0/32 is subnetted, 1 subnets
D 22.22.22.22 [90/130816] via 10.4.22.22, 3d15h, Vlan422
24.0.0.0/32 is subnetted, 1 subnets
D 24.24.24.24 [90/27008512] via 10.4.22.22, 00:10:21, Vlan422
33.0.0.0/32 is subnetted, 1 subnets
D 33.33.33.33 [90/27008256] via 10.4.22.22, 00:10:21, Vlan422
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
D 172.16.103.0/24 [90/26880512] via 10.4.22.22, 00:10:21, Vlan422
SW3 and SW4 both point to IOS22, this is the hub side effect of modifying the tunnel delay.
IOS33#sh ip route eigrp
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, p - overrides from PfR
Gateway of last resort is 172.16.103.24 to network 0.0.0.0
D*EX 0.0.0.0/0 [170/3072] via 172.16.103.24, 1d13h, GigabitEthernet0/0
10.0.0.0/8 is variably subnetted, 11 subnets, 2 masks
D 10.3.9.0/24 [90/26880256] via 10.1.1.9, 1d00h, Tunnel1
D 10.3.22.0/24 [90/26880256] via 10.1.1.22, 1d00h, Tunnel1
D 10.4.9.0/24 [90/26880256] via 10.1.1.9, 1d00h, Tunnel1
D 10.4.22.0/24 [90/26880256] via 10.1.1.22, 1d00h, Tunnel1
D 10.11.19.0/24 [90/28160256] via 10.1.1.22, 00:09:26, Tunnel1
D EX 10.102.12.0/24 [170/28160512] via 10.1.1.22, 00:09:26, Tunnel1
D EX 10.102.15.0/24 [170/28160512] via 10.1.1.22, 00:09:26, Tunnel1
D EX 10.102.25.0/24 [170/28160256] via 10.1.1.22, 00:09:26, Tunnel1
D EX 10.255.10.0/24
[170/3072] via 172.16.103.24, 00:09:26, GigabitEthernet0/0
19.0.0.0/32 is subnetted, 1 subnets
D 19.19.19.19 [90/28288256] via 10.1.1.22, 00:09:26, Tunnel1
20.0.0.0/32 is subnetted, 1 subnets
D EX 20.20.20.20 [170/28288256] via 10.1.1.22, 00:09:26, Tunnel1
22.0.0.0/32 is subnetted, 1 subnets
D 22.22.22.22 [90/27008000] via 10.1.1.22, 1d00h, Tunnel1
24.0.0.0/32 is subnetted, 1 subnets
D 24.24.24.24
[90/130816] via 172.16.103.24, 00:09:26, GigabitEthernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
D 172.16.101.0/24 [90/26880512] via 10.1.1.22, 1d00h, Tunnel1
[90/26880512] via 10.1.1.9, 1d00h, Tunnel1
However, on the spoke side, we see a little bit different output, the other spoke routes are seen as coming from IOS22. However, the 172.16.101.0/24 route is still coming from both hubs.
IOS33#sh ip route 172.16.101.0
Routing entry for 172.16.101.0/24
Known via "eigrp 1", distance 90, metric 26880512, type internal
Redistributing via eigrp 1
Last update from 10.1.1.9 on Tunnel1, 00:00:14 ago
Routing Descriptor Blocks:
* 10.1.1.22, from 10.1.1.22, 00:00:14 ago, via Tunnel1
Route metric is 26880512, traffic share count is 1
Total delay is 50020 microseconds, minimum bandwidth is 100 Kbit
Reliability 255/255, minimum MTU 1400 bytes
Loading 1/255, Hops 2
10.1.1.9, from 10.1.1.9, 00:00:14 ago, via Tunnel1
Route metric is 26880512, traffic share count is 1
Total delay is 50020 microseconds, minimum bandwidth is 100 Kbit
Reliability 255/255, minimum MTU 1400 bytes
Loading 1/255, Hops 2
We see that the route is being learned from both hubs. There are 2 different ways to modify this. One is summarization on the backup hub or CSR9, this takes advantage of longer match routing. Traffic will prefer IOS22, if IOS22 fails, then the shorter summary route via CSR9 will be preferred. The other method is spokes side administrative distance modification.
CSR9
interface tunnel1
ip summary-address eigrp 1 172.16.0.0/16
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 10.1.1.33 (Tunnel1) is resync: summary configured
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 10.1.1.11 (Tunnel1) is resync: summary configured
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 10.1.1.25 (Tunnel1) is resync: summary configured
We can see that both routes are learned, both show up in the routing table. In this case, the longer match will win from a forwarding perspective.
IOS33#sh ip route eigrp
172.16.0.0/16 is variably subnetted, 4 subnets, 3 masks
D 172.16.0.0/16 [90/26880512] via 10.1.1.9, 00:00:08, Tunnel1
D 172.16.101.0/24 [90/26880512] via 10.1.1.22, 00:00:08, Tunnel1
IOS33#show ip route 172.16.0.0
Routing entry for 172.16.0.0/16, 4 known subnets
Attached (2 connections)
Variably subnetted with 3 masks
Redistributing via eigrp 1, nhrp
D 172.16.0.0/16 [90/26880512] via 10.1.1.9, 00:00:27, Tunnel1
D 172.16.101.0/24 [90/26880512] via 10.1.1.22, 00:00:27, Tunnel1
C 172.16.103.0/24 is directly connected, GigabitEthernet0/0
L 172.16.103.33/32 is directly connected, GigabitEthernet0/0
IOS33#show ip route 172.16.101.0
Routing entry for 172.16.101.0/24
Known via "eigrp 1", distance 90, metric 26880512, type internal
Redistributing via eigrp 1
Last update from 10.1.1.22 on Tunnel1, 00:00:34 ago
Routing Descriptor Blocks:
* 10.1.1.22, from 10.1.1.22, 00:00:34 ago, via Tunnel1
Route metric is 26880512, traffic share count is 1
Total delay is 50020 microseconds, minimum bandwidth is 100 Kbit
Reliability 255/255, minimum MTU 1400 bytes
Loading 2/255, Hops 2
We see when we examine the routes more closely that with the summarization in place, we still see the route, summary and the longer match. Traffic will be forwarded via the IOS22 path.
IOS33#show ip eigrp topology 172.16.101.0/24
EIGRP-IPv4 Topology Entry for AS(1)/ID(33.33.33.33) for 172.16.101.0/24
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 26880512
Descriptor Blocks:
10.1.1.22 (Tunnel1), from 10.1.1.22, Send flag is 0x0
Composite metric is (26880512/3072), route is Internal
Vector metric:
Minimum bandwidth is 100 Kbit
Total delay is 50020 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1400
Hop count is 2
Originating router is 3.3.3.3
IOS33#show ip eigrp topology 172.16.101.0/24
EIGRP-IPv4 Topology Entry for AS(1)/ID(33.33.33.33) for 172.16.101.0/24
State is Passive, Query origin flag is 1, 2 Successor(s), FD is 26880512
Descriptor Blocks:
10.1.1.9 (Tunnel1), from 10.1.1.9, Send flag is 0x0
Composite metric is (26880512/3072), route is Internal
Vector metric:
Minimum bandwidth is 100 Kbit
Total delay is 50020 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1400
Hop count is 2
Originating router is 3.3.3.3
10.1.1.22 (Tunnel1), from 10.1.1.22, Send flag is 0x0
Composite metric is (26880512/3072), route is Internal
Vector metric:
Minimum bandwidth is 100 Kbit
Total delay is 50020 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1400
Hop count is 2
Originating router is 3.3.3.3
The last variation we'll look at is the EIGRP distance for routes received from CSR9.
IOS33#sh run | sec eigrp
router eigrp 1
distance 91 10.1.1.9 0.0.0.0
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 10.1.1.9 (Tunnel1) is down: route configuration changed
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 172.16.103.24 (GigabitEthernet0/0) is down: route configuration changed
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 10.1.1.22 (Tunnel1) is down: route configuration changed
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 172.16.103.24 (GigabitEthernet0/0) is up: new adjacency
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 10.1.1.22 (Tunnel1) is up: new adjacency
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 10.1.1.9 (Tunnel1) is up: new adjacency
The EIGRP adjacencies bounce and the re-establish.
IOS33#show ip protocols
Routing Protocol is "eigrp 1"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
EIGRP-IPv4 Protocol for AS(1)
Metric weight K1=1, K2=0, K3=1, K4=0, K5=0
Soft SIA disabled
NSF-aware route hold timer is 240
Router-ID: 33.33.33.33
Topology : 0 (base)
Active Timer: 3 min
Distance: internal 90 external 170
Maximum path: 4
Maximum hopcount 100
Maximum metric variance 1
Automatic Summarization: disabled
Maximum path: 4
Routing for Networks:
10.1.1.0/24
33.33.33.33/32
172.16.103.0/24
Routing Information Sources:
Gateway Distance Last Update
10.1.1.9 91 00:01:29
10.1.1.22 90 00:01:29
172.16.103.24 90 00:01:29
Distance: internal 90 external 170
Address Wild mask Distance List
10.1.1.9 0.0.0.0 91
There is only one way, to my knowledge, to check if the distance modification was successfully implemented. We can see that for routes learned from CSR9 that we are applying a distance of 91.
IOS33#sh ip route eigrp
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, p - overrides from PfR
Gateway of last resort is 172.16.103.24 to network 0.0.0.0
D*EX 0.0.0.0/0 [170/3072] via 172.16.103.24, 00:01:36, GigabitEthernet0/0
10.0.0.0/8 is variably subnetted, 11 subnets, 2 masks
D 10.3.9.0/24 [90/26880512] via 10.1.1.22, 00:01:36, Tunnel1
D 10.3.22.0/24 [90/26880256] via 10.1.1.22, 00:01:36, Tunnel1
D 10.4.9.0/24 [90/26880512] via 10.1.1.22, 00:01:36, Tunnel1
D 10.4.22.0/24 [90/26880256] via 10.1.1.22, 00:01:36, Tunnel1
D 10.11.19.0/24 [90/28160256] via 10.1.1.22, 00:01:36, Tunnel1
D EX 10.102.12.0/24 [170/28160512] via 10.1.1.22, 00:01:36, Tunnel1
D EX 10.102.15.0/24 [170/28160512] via 10.1.1.22, 00:01:36, Tunnel1
D EX 10.102.25.0/24 [170/28160256] via 10.1.1.22, 00:01:36, Tunnel1
D EX 10.255.10.0/24
[170/3072] via 172.16.103.24, 00:01:36, GigabitEthernet0/0
19.0.0.0/32 is subnetted, 1 subnets
D 19.19.19.19 [90/28288256] via 10.1.1.22, 00:01:36, Tunnel1
20.0.0.0/32 is subnetted, 1 subnets
D EX 20.20.20.20 [170/28288256] via 10.1.1.22, 00:01:36, Tunnel1
22.0.0.0/32 is subnetted, 1 subnets
D 22.22.22.22 [90/27008000] via 10.1.1.22, 00:01:36, Tunnel1
24.0.0.0/32 is subnetted, 1 subnets
D 24.24.24.24
[90/130816] via 172.16.103.24, 00:01:36, GigabitEthernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
D 172.16.101.0/24 [90/26880512] via 10.1.1.22, 00:01:36, Tunnel1
This effectively makes the change in the routing table.
Hub Side - SW3
SW3#sh 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 10.3.22.22 to network 0.0.0.0
D*EX 0.0.0.0/0 [170/26880768] via 10.3.22.22, 1d09h, Vlan322
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback0
10.0.0.0/8 is variably subnetted, 24 subnets, 2 masks
D 10.1.1.0/24 [90/26880256] via 10.3.22.22, 22:03:05, Vlan322
[90/26880256] via 10.3.9.9, 22:03:05, Vlan39
C 10.1.3.0/24 is directly connected, Vlan31
L 10.1.3.3/32 is directly connected, Vlan31
C 10.2.3.0/24 is directly connected, Vlan32
L 10.2.3.3/32 is directly connected, Vlan32
C 10.3.6.0/24 is directly connected, Vlan36
L 10.3.6.3/32 is directly connected, Vlan36
C 10.3.9.0/24 is directly connected, Vlan39
L 10.3.9.3/32 is directly connected, Vlan39
C 10.3.13.0/24 is directly connected, Vlan313
L 10.3.13.3/32 is directly connected, Vlan313
C 10.3.14.0/24 is directly connected, Vlan314
L 10.3.14.3/32 is directly connected, Vlan314
C 10.3.22.0/24 is directly connected, Vlan322
L 10.3.22.3/32 is directly connected, Vlan322
C 10.3.23.0/24 is directly connected, Vlan323
L 10.3.23.3/32 is directly connected, Vlan323
D 10.4.9.0/24 [90/3072] via 172.16.101.4, 3d16h, Vlan101
[90/3072] via 10.3.9.9, 3d16h, Vlan39
D 10.4.22.0/24 [90/3072] via 172.16.101.4, 3d16h, Vlan101
[90/3072] via 10.3.22.22, 3d16h, Vlan322
D 10.11.19.0/24 [90/26880512] via 10.3.22.22, 22:00:53, Vlan322
[90/26880512] via 10.3.9.9, 22:00:53, Vlan39
D EX 10.102.12.0/24 [170/26880768] via 10.3.22.22, 22:01:24, Vlan322
[170/26880768] via 10.3.9.9, 22:01:24, Vlan39
D EX 10.102.15.0/24 [170/26880768] via 10.3.22.22, 22:01:24, Vlan322
[170/26880768] via 10.3.9.9, 22:01:24, Vlan39
D EX 10.102.25.0/24 [170/26880512] via 10.3.22.22, 22:01:24, Vlan322
[170/26880512] via 10.3.9.9, 22:01:24, Vlan39
D EX 10.255.10.0/24 [170/26880768] via 10.3.22.22, 21:59:54, Vlan322
[170/26880768] via 10.3.9.9, 21:59:54, Vlan39
19.0.0.0/32 is subnetted, 1 subnets
D 19.19.19.19 [90/27008512] via 10.3.22.22, 22:00:53, Vlan322
[90/27008512] via 10.3.9.9, 22:00:53, Vlan39
20.0.0.0/32 is subnetted, 1 subnets
D EX 20.20.20.20 [170/27008512] via 10.3.22.22, 22:01:24, Vlan322
[170/27008512] via 10.3.9.9, 22:01:24, Vlan39
22.0.0.0/32 is subnetted, 1 subnets
D 22.22.22.22 [90/130816] via 10.3.22.22, 4d02h, Vlan322
24.0.0.0/32 is subnetted, 1 subnets
D 24.24.24.24 [90/27008512] via 10.3.22.22, 21:59:54, Vlan322
[90/27008512] via 10.3.9.9, 21:59:54, Vlan39
33.0.0.0/32 is subnetted, 1 subnets
D 33.33.33.33 [90/27008256] via 10.3.22.22, 21:59:54, Vlan322
[90/27008256] via 10.3.9.9, 21:59:54, Vlan39
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
C 172.16.101.0/24 is directly connected, Vlan101
L 172.16.101.3/32 is directly connected, Vlan101
D 172.16.103.0/24 [90/26880512] via 10.3.22.22, 21:59:54, Vlan322
[90/26880512] via 10.3.9.9, 21:59:54, Vlan39
Hub Side - SW4
SW4#sh 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 10.4.22.22 to network 0.0.0.0
D*EX 0.0.0.0/0 [170/26880768] via 10.4.22.22, 1d09h, Vlan422
4.0.0.0/32 is subnetted, 1 subnets
C 4.4.4.4 is directly connected, Loopback0
10.0.0.0/8 is variably subnetted, 24 subnets, 2 masks
D 10.1.1.0/24 [90/26880256] via 10.4.22.22, 21:45:04, Vlan422
[90/26880256] via 10.4.9.9, 21:45:04, Vlan49
C 10.1.4.0/24 is directly connected, Vlan41
L 10.1.4.4/32 is directly connected, Vlan41
C 10.2.4.0/24 is directly connected, Vlan42
L 10.2.4.4/32 is directly connected, Vlan42
D 10.3.9.0/24 [90/3072] via 172.16.101.3, 3d15h, Vlan101
[90/3072] via 10.4.9.9, 3d15h, Vlan49
D 10.3.22.0/24 [90/3072] via 172.16.101.3, 3d15h, Vlan101
[90/3072] via 10.4.22.22, 3d15h, Vlan422
C 10.4.6.0/24 is directly connected, Vlan46
L 10.4.6.4/32 is directly connected, Vlan46
C 10.4.9.0/24 is directly connected, Vlan49
L 10.4.9.4/32 is directly connected, Vlan49
C 10.4.13.0/24 is directly connected, Vlan413
L 10.4.13.4/32 is directly connected, Vlan413
C 10.4.14.0/24 is directly connected, Vlan414
L 10.4.14.4/32 is directly connected, Vlan414
C 10.4.22.0/24 is directly connected, Vlan422
L 10.4.22.4/32 is directly connected, Vlan422
C 10.4.23.0/24 is directly connected, Vlan423
L 10.4.23.4/32 is directly connected, Vlan423
D 10.11.19.0/24 [90/26880512] via 10.4.22.22, 21:42:54, Vlan422
[90/26880512] via 10.4.9.9, 21:42:54, Vlan49
D EX 10.102.12.0/24 [170/26880768] via 10.4.22.22, 21:43:24, Vlan422
[170/26880768] via 10.4.9.9, 21:43:24, Vlan49
D EX 10.102.15.0/24 [170/26880768] via 10.4.22.22, 21:43:24, Vlan422
[170/26880768] via 10.4.9.9, 21:43:24, Vlan49
D EX 10.102.25.0/24 [170/26880512] via 10.4.22.22, 21:43:24, Vlan422
[170/26880512] via 10.4.9.9, 21:43:24, Vlan49
D EX 10.255.10.0/24 [170/26880768] via 10.4.22.22, 21:41:56, Vlan422
[170/26880768] via 10.4.9.9, 21:41:56, Vlan49
19.0.0.0/32 is subnetted, 1 subnets
D 19.19.19.19 [90/27008512] via 10.4.22.22, 21:42:54, Vlan422
[90/27008512] via 10.4.9.9, 21:42:54, Vlan49
20.0.0.0/32 is subnetted, 1 subnets
D EX 20.20.20.20 [170/27008512] via 10.4.22.22, 21:43:24, Vlan422
[170/27008512] via 10.4.9.9, 21:43:24, Vlan49
22.0.0.0/32 is subnetted, 1 subnets
D 22.22.22.22 [90/130816] via 10.4.22.22, 3d15h, Vlan422
24.0.0.0/32 is subnetted, 1 subnets
D 24.24.24.24 [90/27008512] via 10.4.22.22, 21:41:56, Vlan422
[90/27008512] via 10.4.9.9, 21:41:56, Vlan49
33.0.0.0/32 is subnetted, 1 subnets
D 33.33.33.33 [90/27008256] via 10.4.22.22, 21:41:56, Vlan422
[90/27008256] via 10.4.9.9, 21:41:56, Vlan49
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
C 172.16.101.0/24 is directly connected, Vlan101
L 172.16.101.4/32 is directly connected, Vlan101
D 172.16.103.0/24 [90/26880512] via 10.4.22.22, 21:41:56, Vlan422
[90/26880512] via 10.4.9.9, 21:41:56, Vlan49
IOS33#sh ip route eigrp
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, p - overrides from PfR
Gateway of last resort is 172.16.103.24 to network 0.0.0.0
D*EX 0.0.0.0/0 [170/3072] via 172.16.103.24, 1d12h, GigabitEthernet0/0
10.0.0.0/8 is variably subnetted, 11 subnets, 2 masks
D 10.3.9.0/24 [90/26880256] via 10.1.1.9, 1d00h, Tunnel1
D 10.3.22.0/24 [90/26880256] via 10.1.1.22, 1d00h, Tunnel1
D 10.4.9.0/24 [90/26880256] via 10.1.1.9, 1d00h, Tunnel1
D 10.4.22.0/24 [90/26880256] via 10.1.1.22, 1d00h, Tunnel1
D 10.11.19.0/24 [90/28160256] via 10.1.1.22, 1d00h, Tunnel1
[90/28160256] via 10.1.1.9, 1d00h, Tunnel1
D EX 10.102.12.0/24 [170/28160512] via 10.1.1.22, 1d00h, Tunnel1
[170/28160512] via 10.1.1.9, 1d00h, Tunnel1
D EX 10.102.15.0/24 [170/28160512] via 10.1.1.22, 1d00h, Tunnel1
[170/28160512] via 10.1.1.9, 1d00h, Tunnel1
D EX 10.102.25.0/24 [170/28160256] via 10.1.1.22, 1d00h, Tunnel1
[170/28160256] via 10.1.1.9, 1d00h, Tunnel1
D EX 10.255.10.0/24
[170/3072] via 172.16.103.24, 1d00h, GigabitEthernet0/0
19.0.0.0/32 is subnetted, 1 subnets
D 19.19.19.19 [90/28288256] via 10.1.1.22, 1d00h, Tunnel1
[90/28288256] via 10.1.1.9, 1d00h, Tunnel1
20.0.0.0/32 is subnetted, 1 subnets
D EX 20.20.20.20 [170/28288256] via 10.1.1.22, 1d00h, Tunnel1
[170/28288256] via 10.1.1.9, 1d00h, Tunnel1
22.0.0.0/32 is subnetted, 1 subnets
D 22.22.22.22 [90/27008000] via 10.1.1.22, 1d00h, Tunnel1
24.0.0.0/32 is subnetted, 1 subnets
D 24.24.24.24 [90/130816] via 172.16.103.24, 1d00h, GigabitEthernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
D 172.16.101.0/24 [90/26880512] via 10.1.1.22, 1d00h, Tunnel1
[90/26880512] via 10.1.1.9, 1d00h, Tunnel1
We see that the routing table has not been modified yet.
CSR9
interface Tunnel1
delay 10000
CSR9#show int tun1
Tunnel1 is up, line protocol is up
Hardware is Tunnel
Internet address is 10.1.1.9/24
MTU 9972 bytes, BW 100 Kbit/sec, DLY 100000 usec,
The normal, default is 50000 microseconds, which is what IOS22 is set to.
IOS22#sh int tun1
Tunnel1 is up, line protocol is up
Hardware is Tunnel
Internet address is 10.1.1.22/24
MTU 17912 bytes, BW 100 Kbit/sec, DLY 50000 usec,
We modify the tunnel interface on CSR9 to 10000 which puts 100,000 mircoseconds of delay on the tunnel, make it effective on the switches behind CSR9 and the spokes to prefer the IOS22 hub.
SW3#sh ip route eigrp
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 10.3.22.22 to network 0.0.0.0
D*EX 0.0.0.0/0 [170/26880768] via 10.3.22.22, 1d09h, Vlan322
10.0.0.0/8 is variably subnetted, 24 subnets, 2 masks
D 10.1.1.0/24 [90/26880256] via 10.3.22.22, 00:09:42, Vlan322
D 10.4.9.0/24 [90/3072] via 172.16.101.4, 3d16h, Vlan101
[90/3072] via 10.3.9.9, 3d16h, Vlan39
D 10.4.22.0/24 [90/3072] via 172.16.101.4, 3d16h, Vlan101
[90/3072] via 10.3.22.22, 3d16h, Vlan322
D 10.11.19.0/24 [90/26880512] via 10.3.22.22, 00:09:46, Vlan322
D EX 10.102.12.0/24 [170/26880768] via 10.3.22.22, 00:09:46, Vlan322
D EX 10.102.15.0/24 [170/26880768] via 10.3.22.22, 00:09:46, Vlan322
D EX 10.102.25.0/24 [170/26880512] via 10.3.22.22, 00:09:46, Vlan322
D EX 10.255.10.0/24 [170/26880768] via 10.3.22.22, 00:09:46, Vlan322
19.0.0.0/32 is subnetted, 1 subnets
D 19.19.19.19 [90/27008512] via 10.3.22.22, 00:09:46, Vlan322
20.0.0.0/32 is subnetted, 1 subnets
D EX 20.20.20.20 [170/27008512] via 10.3.22.22, 00:09:46, Vlan322
22.0.0.0/32 is subnetted, 1 subnets
D 22.22.22.22 [90/130816] via 10.3.22.22, 4d02h, Vlan322
24.0.0.0/32 is subnetted, 1 subnets
D 24.24.24.24 [90/27008512] via 10.3.22.22, 00:09:46, Vlan322
33.0.0.0/32 is subnetted, 1 subnets
D 33.33.33.33 [90/27008256] via 10.3.22.22, 00:09:46, Vlan322
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
D 172.16.103.0/24 [90/26880512] via 10.3.22.22, 00:09:46, Vlan322
SW4#sh ip route eigrp
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 10.4.22.22 to network 0.0.0.0
D*EX 0.0.0.0/0 [170/26880768] via 10.4.22.22, 1d09h, Vlan422
10.0.0.0/8 is variably subnetted, 24 subnets, 2 masks
D 10.1.1.0/24 [90/26880256] via 10.4.22.22, 00:10:17, Vlan422
D 10.3.9.0/24 [90/3072] via 172.16.101.3, 3d15h, Vlan101
[90/3072] via 10.4.9.9, 3d15h, Vlan49
D 10.3.22.0/24 [90/3072] via 172.16.101.3, 3d15h, Vlan101
[90/3072] via 10.4.22.22, 3d15h, Vlan422
D 10.11.19.0/24 [90/26880512] via 10.4.22.22, 00:10:21, Vlan422
D EX 10.102.12.0/24 [170/26880768] via 10.4.22.22, 00:10:21, Vlan422
D EX 10.102.15.0/24 [170/26880768] via 10.4.22.22, 00:10:21, Vlan422
D EX 10.102.25.0/24 [170/26880512] via 10.4.22.22, 00:10:21, Vlan422
D EX 10.255.10.0/24 [170/26880768] via 10.4.22.22, 00:10:21, Vlan422
19.0.0.0/32 is subnetted, 1 subnets
D 19.19.19.19 [90/27008512] via 10.4.22.22, 00:10:21, Vlan422
20.0.0.0/32 is subnetted, 1 subnets
D EX 20.20.20.20 [170/27008512] via 10.4.22.22, 00:10:21, Vlan422
22.0.0.0/32 is subnetted, 1 subnets
D 22.22.22.22 [90/130816] via 10.4.22.22, 3d15h, Vlan422
24.0.0.0/32 is subnetted, 1 subnets
D 24.24.24.24 [90/27008512] via 10.4.22.22, 00:10:21, Vlan422
33.0.0.0/32 is subnetted, 1 subnets
D 33.33.33.33 [90/27008256] via 10.4.22.22, 00:10:21, Vlan422
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
D 172.16.103.0/24 [90/26880512] via 10.4.22.22, 00:10:21, Vlan422
SW3 and SW4 both point to IOS22, this is the hub side effect of modifying the tunnel delay.
IOS33#sh ip route eigrp
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, p - overrides from PfR
Gateway of last resort is 172.16.103.24 to network 0.0.0.0
D*EX 0.0.0.0/0 [170/3072] via 172.16.103.24, 1d13h, GigabitEthernet0/0
10.0.0.0/8 is variably subnetted, 11 subnets, 2 masks
D 10.3.9.0/24 [90/26880256] via 10.1.1.9, 1d00h, Tunnel1
D 10.3.22.0/24 [90/26880256] via 10.1.1.22, 1d00h, Tunnel1
D 10.4.9.0/24 [90/26880256] via 10.1.1.9, 1d00h, Tunnel1
D 10.4.22.0/24 [90/26880256] via 10.1.1.22, 1d00h, Tunnel1
D 10.11.19.0/24 [90/28160256] via 10.1.1.22, 00:09:26, Tunnel1
D EX 10.102.12.0/24 [170/28160512] via 10.1.1.22, 00:09:26, Tunnel1
D EX 10.102.15.0/24 [170/28160512] via 10.1.1.22, 00:09:26, Tunnel1
D EX 10.102.25.0/24 [170/28160256] via 10.1.1.22, 00:09:26, Tunnel1
D EX 10.255.10.0/24
[170/3072] via 172.16.103.24, 00:09:26, GigabitEthernet0/0
19.0.0.0/32 is subnetted, 1 subnets
D 19.19.19.19 [90/28288256] via 10.1.1.22, 00:09:26, Tunnel1
20.0.0.0/32 is subnetted, 1 subnets
D EX 20.20.20.20 [170/28288256] via 10.1.1.22, 00:09:26, Tunnel1
22.0.0.0/32 is subnetted, 1 subnets
D 22.22.22.22 [90/27008000] via 10.1.1.22, 1d00h, Tunnel1
24.0.0.0/32 is subnetted, 1 subnets
D 24.24.24.24
[90/130816] via 172.16.103.24, 00:09:26, GigabitEthernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
D 172.16.101.0/24 [90/26880512] via 10.1.1.22, 1d00h, Tunnel1
[90/26880512] via 10.1.1.9, 1d00h, Tunnel1
However, on the spoke side, we see a little bit different output, the other spoke routes are seen as coming from IOS22. However, the 172.16.101.0/24 route is still coming from both hubs.
IOS33#sh ip route 172.16.101.0
Routing entry for 172.16.101.0/24
Known via "eigrp 1", distance 90, metric 26880512, type internal
Redistributing via eigrp 1
Last update from 10.1.1.9 on Tunnel1, 00:00:14 ago
Routing Descriptor Blocks:
* 10.1.1.22, from 10.1.1.22, 00:00:14 ago, via Tunnel1
Route metric is 26880512, traffic share count is 1
Total delay is 50020 microseconds, minimum bandwidth is 100 Kbit
Reliability 255/255, minimum MTU 1400 bytes
Loading 1/255, Hops 2
10.1.1.9, from 10.1.1.9, 00:00:14 ago, via Tunnel1
Route metric is 26880512, traffic share count is 1
Total delay is 50020 microseconds, minimum bandwidth is 100 Kbit
Reliability 255/255, minimum MTU 1400 bytes
Loading 1/255, Hops 2
We see that the route is being learned from both hubs. There are 2 different ways to modify this. One is summarization on the backup hub or CSR9, this takes advantage of longer match routing. Traffic will prefer IOS22, if IOS22 fails, then the shorter summary route via CSR9 will be preferred. The other method is spokes side administrative distance modification.
CSR9
interface tunnel1
ip summary-address eigrp 1 172.16.0.0/16
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 10.1.1.33 (Tunnel1) is resync: summary configured
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 10.1.1.11 (Tunnel1) is resync: summary configured
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 10.1.1.25 (Tunnel1) is resync: summary configured
We can see that both routes are learned, both show up in the routing table. In this case, the longer match will win from a forwarding perspective.
IOS33#sh ip route eigrp
172.16.0.0/16 is variably subnetted, 4 subnets, 3 masks
D 172.16.0.0/16 [90/26880512] via 10.1.1.9, 00:00:08, Tunnel1
D 172.16.101.0/24 [90/26880512] via 10.1.1.22, 00:00:08, Tunnel1
IOS33#show ip route 172.16.0.0
Routing entry for 172.16.0.0/16, 4 known subnets
Attached (2 connections)
Variably subnetted with 3 masks
Redistributing via eigrp 1, nhrp
D 172.16.0.0/16 [90/26880512] via 10.1.1.9, 00:00:27, Tunnel1
D 172.16.101.0/24 [90/26880512] via 10.1.1.22, 00:00:27, Tunnel1
C 172.16.103.0/24 is directly connected, GigabitEthernet0/0
L 172.16.103.33/32 is directly connected, GigabitEthernet0/0
IOS33#show ip route 172.16.101.0
Routing entry for 172.16.101.0/24
Known via "eigrp 1", distance 90, metric 26880512, type internal
Redistributing via eigrp 1
Last update from 10.1.1.22 on Tunnel1, 00:00:34 ago
Routing Descriptor Blocks:
* 10.1.1.22, from 10.1.1.22, 00:00:34 ago, via Tunnel1
Route metric is 26880512, traffic share count is 1
Total delay is 50020 microseconds, minimum bandwidth is 100 Kbit
Reliability 255/255, minimum MTU 1400 bytes
Loading 2/255, Hops 2
We see when we examine the routes more closely that with the summarization in place, we still see the route, summary and the longer match. Traffic will be forwarded via the IOS22 path.
IOS33#show ip eigrp topology 172.16.101.0/24
EIGRP-IPv4 Topology Entry for AS(1)/ID(33.33.33.33) for 172.16.101.0/24
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 26880512
Descriptor Blocks:
10.1.1.22 (Tunnel1), from 10.1.1.22, Send flag is 0x0
Composite metric is (26880512/3072), route is Internal
Vector metric:
Minimum bandwidth is 100 Kbit
Total delay is 50020 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1400
Hop count is 2
Originating router is 3.3.3.3
IOS33#show ip eigrp topology 172.16.101.0/24
EIGRP-IPv4 Topology Entry for AS(1)/ID(33.33.33.33) for 172.16.101.0/24
State is Passive, Query origin flag is 1, 2 Successor(s), FD is 26880512
Descriptor Blocks:
10.1.1.9 (Tunnel1), from 10.1.1.9, Send flag is 0x0
Composite metric is (26880512/3072), route is Internal
Vector metric:
Minimum bandwidth is 100 Kbit
Total delay is 50020 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1400
Hop count is 2
Originating router is 3.3.3.3
10.1.1.22 (Tunnel1), from 10.1.1.22, Send flag is 0x0
Composite metric is (26880512/3072), route is Internal
Vector metric:
Minimum bandwidth is 100 Kbit
Total delay is 50020 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1400
Hop count is 2
Originating router is 3.3.3.3
The last variation we'll look at is the EIGRP distance for routes received from CSR9.
IOS33#sh run | sec eigrp
router eigrp 1
distance 91 10.1.1.9 0.0.0.0
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 10.1.1.9 (Tunnel1) is down: route configuration changed
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 172.16.103.24 (GigabitEthernet0/0) is down: route configuration changed
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 10.1.1.22 (Tunnel1) is down: route configuration changed
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 172.16.103.24 (GigabitEthernet0/0) is up: new adjacency
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 10.1.1.22 (Tunnel1) is up: new adjacency
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 10.1.1.9 (Tunnel1) is up: new adjacency
The EIGRP adjacencies bounce and the re-establish.
IOS33#show ip protocols
Routing Protocol is "eigrp 1"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
EIGRP-IPv4 Protocol for AS(1)
Metric weight K1=1, K2=0, K3=1, K4=0, K5=0
Soft SIA disabled
NSF-aware route hold timer is 240
Router-ID: 33.33.33.33
Topology : 0 (base)
Active Timer: 3 min
Distance: internal 90 external 170
Maximum path: 4
Maximum hopcount 100
Maximum metric variance 1
Automatic Summarization: disabled
Maximum path: 4
Routing for Networks:
10.1.1.0/24
33.33.33.33/32
172.16.103.0/24
Routing Information Sources:
Gateway Distance Last Update
10.1.1.9 91 00:01:29
10.1.1.22 90 00:01:29
172.16.103.24 90 00:01:29
Distance: internal 90 external 170
Address Wild mask Distance List
10.1.1.9 0.0.0.0 91
There is only one way, to my knowledge, to check if the distance modification was successfully implemented. We can see that for routes learned from CSR9 that we are applying a distance of 91.
IOS33#sh ip route eigrp
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, p - overrides from PfR
Gateway of last resort is 172.16.103.24 to network 0.0.0.0
D*EX 0.0.0.0/0 [170/3072] via 172.16.103.24, 00:01:36, GigabitEthernet0/0
10.0.0.0/8 is variably subnetted, 11 subnets, 2 masks
D 10.3.9.0/24 [90/26880512] via 10.1.1.22, 00:01:36, Tunnel1
D 10.3.22.0/24 [90/26880256] via 10.1.1.22, 00:01:36, Tunnel1
D 10.4.9.0/24 [90/26880512] via 10.1.1.22, 00:01:36, Tunnel1
D 10.4.22.0/24 [90/26880256] via 10.1.1.22, 00:01:36, Tunnel1
D 10.11.19.0/24 [90/28160256] via 10.1.1.22, 00:01:36, Tunnel1
D EX 10.102.12.0/24 [170/28160512] via 10.1.1.22, 00:01:36, Tunnel1
D EX 10.102.15.0/24 [170/28160512] via 10.1.1.22, 00:01:36, Tunnel1
D EX 10.102.25.0/24 [170/28160256] via 10.1.1.22, 00:01:36, Tunnel1
D EX 10.255.10.0/24
[170/3072] via 172.16.103.24, 00:01:36, GigabitEthernet0/0
19.0.0.0/32 is subnetted, 1 subnets
D 19.19.19.19 [90/28288256] via 10.1.1.22, 00:01:36, Tunnel1
20.0.0.0/32 is subnetted, 1 subnets
D EX 20.20.20.20 [170/28288256] via 10.1.1.22, 00:01:36, Tunnel1
22.0.0.0/32 is subnetted, 1 subnets
D 22.22.22.22 [90/27008000] via 10.1.1.22, 00:01:36, Tunnel1
24.0.0.0/32 is subnetted, 1 subnets
D 24.24.24.24
[90/130816] via 172.16.103.24, 00:01:36, GigabitEthernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
D 172.16.101.0/24 [90/26880512] via 10.1.1.22, 00:01:36, Tunnel1
This effectively makes the change in the routing table.
