07-28-2012 03:51 PM - edited 03-04-2019 05:05 PM
I am a bit confused about this router config from a branch location of an enterprise network. They use EIGRP tunnels as backups to the HQ.
I have pasted what I believe is relevant to my question. Under the sh ip pro it states:
Address Summarization:
10.102.73.0/24 for Tunnel1, Tunnel2, Tunnel3
but that network is for the inside user LAN. What does this command mean?
And the route table has this EIGRP config:
D 10.102.73.0/24 is a summary, 00:17:44, Null0
Rt1#sh int des
Interface Status Protocol Description
Fa0/0 up up ****TRUNK TO SWITCH****
Fa0/0.1 up up **** POS ****
Fa0/0.2 up up **** Users ****
Fa0/1 up up Verizon DSL circuit
BR0/1/0 up up Verizon ISDN circuit SPID1
BR0/1/0:1 down down
BR0/1/0:2 down down
Lo0 up up
Lo2 up up
Tu1 up up GRE VPN2 Primary Tunnel
Tu2 up up GRE VPN2 Secondary Tunnel
Tu3 up up GRE VPN3 Backup Tunnel to HQ
Rt1#sh ip int brie
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 unassigned YES NVRAM up up
FastEthernet0/0.1 10.102.73.1 YES NVRAM up up
FastEthernet0/0.2 10.102.73.129 YES NVRAM up up
FastEthernet0/1 72.86.158.250 YES NVRAM up up
BRI0/1/0 192.168.1.59 YES NVRAM up up
BRI0/1/0:1 unassigned YES unset down down
BRI0/1/0:2 unassigned YES unset down down
Loopback0 10.202.73.1 YES NVRAM up up
Loopback2 10.90.1.78 YES NVRAM up up
Tunnel1 10.99.5.54 YES NVRAM up up
Tunnel2 10.99.133.54 YES NVRAM up up
Tunnel3 10.99.69.54 YES NVRAM up up
Rt1#sh ip eig ne
IP-EIGRP neighbors for process 100
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
3 10.99.133.53 Tu2 14 01:18:31 459 2754 0 557854279
2 10.99.5.53 Tu1 13 01:18:38 71 426 0 552639512
1 10.99.69.53 Tu3 14 01:18:41 157 942 0 1267476614
66.0.0.0/32 is subnetted, 1 subnets
S 66.187.216.11 [1/0] via 72.86.158.1
216.143.116.0/32 is subnetted, 2 subnets
S 216.143.116.13 [1/0] via 72.86.158.1
S 216.143.116.12 [1/0] via 72.86.158.1
172.31.0.0/32 is subnetted, 2 subnets
S 172.31.0.6 [1/0] via 72.86.158.1
S 172.31.0.10 [1/0] via 72.86.158.1
10.0.0.0/8 is variably subnetted, 9 subnets, 4 masks
C 10.99.69.52/30 is directly connected, Tunnel3
C 10.90.1.78/32 is directly connected, Loopback2
C 10.102.73.0/25 is directly connected, FastEthernet0/0.1
D 10.102.73.0/24 is a summary, 00:17:44, Null0
C 10.99.5.52/30 is directly connected, Tunnel1
C 10.202.73.1/32 is directly connected, Loopback0
C 10.102.73.128/25 is directly connected, FastEthernet0/0.2
C 10.99.133.52/30 is directly connected, Tunnel2
S 10.5.251.12/32 [1/0] via 72.86.158.1
72.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 72.86.158.0/24 is directly connected, FastEthernet0/1
S 72.37.251.30/32 [1/0] via 72.86.158.1
D*EX 0.0.0.0/0 [170/19467008] via 10.99.5.53, 01:18:50, Tunnel1
C 192.168.0.0/22 is directly connected, BRI0/1/0
Rt1#sh ip pro
Routing Protocol is "eigrp 100"
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 metric weight K1=1, K2=0, K3=1, K4=0, K5=0
EIGRP maximum hopcount 100
EIGRP maximum metric variance 1
EIGRP stub, connected, summary
Redistributing: eigrp 100
EIGRP NSF-aware route hold timer is 240s
Automatic network summarization is not in effect
Address Summarization:
10.102.73.0/24 for Tunnel1, Tunnel2, Tunnel3
BRI0/1/0
Summarizing with metric 28160
Maximum path: 4
Routing for Networks:
10.99.5.52/30
10.99.69.52/30
10.99.133.52/30
10.102.73.0/25
10.102.73.128/25
10.202.73.1/32
192.168.0.0/22
Passive Interface(s):
FastEthernet0/0
FastEthernet0/0.1
FastEthernet0/0.2
FastEthernet0/1
BRI0/1/0:1
BRI0/1/0:2
Loopback0
Loopback2
Routing Information Sources:
Gateway Distance Last Update
(this router) 90 00:17:57
10.99.69.53 90 00:17:57
10.99.5.53 90 00:00:05
192.168.1.1 90 01:15:06
10.99.133.53 90 00:00:05
Distance: internal 90 external 170
interface Tunnel1
description GRE VPN2 Primary Tunnel
bandwidth 384
ip address 10.99.5.54 255.255.255.252
ip mtu 1400
ip tcp adjust-mss 1360
ip summary-address eigrp 100 10.102.73.0 255.255.255.0 5
keepalive 20 3
tunnel source Loopback2
tunnel destination 172.31.0.6
end
interface Tunnel2
description GRE VPN2 Secondary Tunnel
bandwidth 384
ip address 10.99.133.54 255.255.255.252
ip mtu 1400
ip tcp adjust-mss 1360
ip summary-address eigrp 100 10.102.73.0 255.255.255.0 5
delay 50010
keepalive 20 3
tunnel source Loopback2
tunnel destination 172.31.0.10
end
interface Tunnel3
description GRE VPN3 Backup Tunnel to Secaucus
bandwidth 256
ip address 10.99.69.54 255.255.255.252
ip mtu 1400
ip tcp adjust-mss 1360
ip summary-address eigrp 100 10.102.73.0 255.255.255.0 5
delay 100000
keepalive 20 3
tunnel source Loopback2
tunnel destination 10.5.251.12
end
Solved! Go to Solution.
07-28-2012 06:28 PM
This router has 2 subnets as local connected subnets within this address space. Rather than advertise the individual subnets the router has configured the summary address command on the tunnel interfaces. The result is that the router advertises one summary instead of the individual subnets. And when summarization is configured EIGRP will install a route for the aggregate with null 0 as the next hop.
HTH
Rick
Sent from Cisco Technical Support iPhone App
07-28-2012 06:28 PM
This router has 2 subnets as local connected subnets within this address space. Rather than advertise the individual subnets the router has configured the summary address command on the tunnel interfaces. The result is that the router advertises one summary instead of the individual subnets. And when summarization is configured EIGRP will install a route for the aggregate with null 0 as the next hop.
HTH
Rick
Sent from Cisco Technical Support iPhone App
07-29-2012 05:34 PM
I am glad that my explanation was helpful. Thank you for using the rating system to mark this question as answered. It makes the forum more useful when people can read a question and can know that an answer was found. Your marking has contributed to this process.
HTH
Rick
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide