OSPF route via backup-connection

gaigl · ‎10-10-2019

Hello,

we have 3 branches connected via leased line to a ISR 4331, the branch router also have a backup-connection via dsl to a backup-router (also ISR 4331), the branch-router have 2 IPSEC-Tunnels: one to the primary router via leased line, one to the backup-router via dsl.

the 3 connections to the branches are area 1, 8 and 16, the 2 HQ roter are ASBR-Router in area 0 and the branch areas.

now I see Network 172.28.0.0 from Branch1 on Router A via Tunnel 0 and on Router B via Tunnel 100.

We're redistributing connected and static in ospf process 1

Now I'm wondering why I don't have in the routing-table of Router1 the Net 172.28.0.0 via Tunnel 100 and Router B (with another metric.

Yesterday I made a backup-test (shutting down Tunnel 0) and clients at branch 1 didn't reach servers in HQ, so maybe the route back from HQ to branch was still routet to routerA, but I think if Router A knows about the route via RouterB and Tunnel 100, it would work.

Am I wrong?

Deepak Kumar · ‎10-10-2019

Hi,

I tested the same in my lab and I am not facing any issue, Can you share your router's configuration.

Regards,
Deepak Kumar,
Don't forget to vote and accept the solution if this comment will help you!

gaigl · ‎10-10-2019

is the the routing Process enough?

Branch1:

Branch 1:
router ospf 1
 router-id 192.168.200.100
 redistribute connected subnets
 network 192.168.191.0 0.0.0.3 area 1
 network 192.168.191.100 0.0.0.3 area 1

Router A:
router ospf 1
 router-id 192.168.200.209
 redistribute connected subnets
 redistribute static subnets
 network 192.168.22.0 0.0.0.255 area 0
 network 192.168.191.0 0.0.0.3 area 1
 network 192.168.191.8 0.0.0.3 area 8
 network 192.168.191.16 0.0.0.3 area 16

Router B:
router ospf 1
 router-id 192.168.200.219
 redistribute connected subnets
 redistribute static subnets
 network 192.168.22.0 0.0.0.255 area 0
 network 192.168.191.100 0.0.0.3 area 1
 network 192.168.191.108 0.0.0.3 area 8
 network 192.168.191.116 0.0.0.3 area 16

sh ip route ospf:

Branch1:
...
O E2  172.27.0.0/16 [110/20] via 192.168.191.2, 22:16:00, Tunnel0 (Net HQ)
...
      192.168.191.0/24 is variably subnetted, 8 subnets, 2 masks
O IA     192.168.191.8/30 [110/10] via 192.168.191.2, 06:14:07, Tunnel0
O IA     192.168.191.16/30 [110/10] via 192.168.191.2, 22:16:00, Tunnel0
O IA     192.168.191.108/30 [110/103] via 192.168.191.102, 1w2d, Tunnel100
O IA     192.168.191.116/30 [110/103] via 192.168.191.102, 1w2d, Tunnel100
      192.168.200.0/32 is subnetted, 3 subnets
O E2     192.168.200.108 [110/20] via 192.168.191.2, 22:16:00, Tunnel0
O E2     192.168.200.116 [110/20] via 192.168.191.2, 22:16:00, Tunnel0
...


Router A:
...
O E2  172.28.0.0/16 [110/20] via 192.168.191.1, 22:18:30, Tunnel0
O E2  172.29.0.0/16 [110/20] via 192.168.191.9, 2w2d, Tunnel8
O E2  172.30.0.0/16 [110/20] via 192.168.191.17, 4w0d, Tunnel16
      192.168.191.0/24 is variably subnetted, 9 subnets, 2 masks
O        192.168.191.100/30 [110/102] via 192.168.191.1, 22:18:30, Tunnel0
O        192.168.191.108/30 [110/105] via 192.168.191.9, 06:16:37, Tunnel8
O IA     192.168.191.116/30
           [110/7] via 192.168.22.34, 00:00:35, GigabitEthernet0/0/1
      192.168.200.0/32 is subnetted, 3 subnets
O E2     192.168.200.100 [110/20] via 192.168.191.1, 22:18:30, Tunnel0
O E2     192.168.200.108 [110/20] via 192.168.191.9, 2w2d, Tunnel8
O E2     192.168.200.116 [110/20] via 192.168.191.17, 4w0d, Tunnel16
...

Router B:

...
O E2  172.28.0.0/16 [110/20] via 192.168.191.101, 1w2d, Tunnel100
O E2  172.29.0.0/16 [110/20] via 192.168.191.109, 1w2d, Tunnel108
O E2  172.30.0.0/16 [110/20] via 192.168.191.117, 00:01:07, Tunnel116
...
      192.168.191.0/24 is variably subnetted, 9 subnets, 2 masks
O        192.168.191.0/30 [110/11] via 192.168.191.101, 1w2d, Tunnel100
O        192.168.191.8/30 [110/30] via 192.168.191.109, 1w2d, Tunnel108
O        192.168.191.16/30 [110/11] via 192.168.191.117, 00:01:07, Tunnel116
      192.168.200.0/32 is subnetted, 3 subnets
O E2     192.168.200.100 [110/20] via 192.168.191.101, 1w2d, Tunnel100
O E2     192.168.200.108 [110/20] via 192.168.191.109, 1w2d, Tunnel108
O E2     192.168.200.116 [110/20] via 192.168.191.117, 00:01:07, Tunnel116
...

some lines I've removed

gaigl · ‎10-10-2019

I'm not sure about:

should I modify on Branch-Router the ospf process 1 that the local connected Net 172.28.0.0 is a network statement in Area 1 ?

Deepak Kumar · ‎10-10-2019

Hi,

Everything is looking fine and Please share the "Show IP OSPF database summary" output from router A and B. I hope there is no route filter is done on the Router A or B.

Regards,
Deepak Kumar,
Don't forget to vote and accept the solution if this comment will help you!

gaigl · ‎10-10-2019

No route filter, file with the summary is attached

Deepak Kumar · ‎10-10-2019

Hi,

Sorry, it was a typo in my last command. As this is an external type route so we can't check with the summary command. Everything is looking good.

Here are my questions:

1. What will happen if you shut down the tunnel interface on Router A? What will be output on "Show IP ospf database external" and "Show IP ospf Database"? Can you see subnet 172.16.0.0/16 advertised by router B?

2. 1. What will happen if you shut down the tunnel interface on Router B? What will be output on "Show IP ospf database external" and "Show IP ospf Database"? Can you see subnet 172.16.0.0/16 advertised by router A?

3. Are Router A and Router B's neighbourship UP?

Regards,
Deepak Kumar,
Don't forget to vote and accept the solution if this comment will help you!

gaigl · ‎10-14-2019

The Neighbourship is up, the rest I'll test next Weekend, cannot test during office-time