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​DMVPN - Dual Hub Single Cloud VRF Aware Phase 3 Path Selection

Picture
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.
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