Ok so I cannot figure this out at all and would like to understand what's going on. This is on a Cisco 7600 platform.
Router B has an uplink to Router A via TenGig3/1. The path to get to 10.251.197.10/24 goes through this link.
RouterB#sh ip ro 10.251.197.0
Routing entry for 10.251.197.0/24
Known via "bgp 64602", distance 200, metric 100, type internal
Last update from 10.252.70.188 00:09:38 ago
Routing Descriptor Blocks:
* 10.252.70.188, from 10.252.70.133, 00:09:38 ago
Route metric is 100, traffic share count is 1
AS Hops 0
RouterB#sh ip ro 10.252.70.133
Routing entry for 10.252.70.133/32
Known via "ospf 33650", distance 110, metric 3, type intra area
Last update from 10.252.38.53 on TenGigabitEthernet3/1, 00:07:14 ago
Routing Descriptor Blocks:
* 10.252.38.53, from 10.252.70.133, 00:07:14 ago, via TenGigabitEthernet3/1
Route metric is 3, traffic share count is 1
RouterB#sh ip cef 10.251.197.0 det
10.251.197.0/24, version 21421, epoch 0
0 packets, 0 bytes
via 10.252.70.188, 0 dependencies, recursive
next hop 10.252.38.53, TenGigabitEthernet3/1 via 10.252.70.188/32 (Default)
valid adjacency
Recursive load sharing using 10.252.70.188/32.
If this link goes down, the routing table will show that it should go out TenGig3/3, but the FIB says it should go out TenGig3/2, which then loops because that router hanging off of 3/2 has no entry in it's routing table for this subnet:
RouterB#sh ip ro 10.251.197.0
Routing entry for 10.251.197.0/24
Known via "bgp 64602", distance 200, metric 100, type internal
Last update from 10.252.70.188 00:13:01 ago
Routing Descriptor Blocks:
* 10.252.70.188, from 10.252.70.133, 00:13:01 ago
Route metric is 100, traffic share count is 1
AS Hops 0
RouterB#sh ip ro 10.252.70.133
Routing entry for 10.252.70.133/32
Known via "ospf 33650", distance 110, metric 6, type intra area
Last update from 10.252.38.86 on TenGigabitEthernet3/3, 00:00:33 ago
Routing Descriptor Blocks:
* 10.252.38.86, from 10.252.70.133, 00:00:33 ago, via TenGigabitEthernet3/3
Route metric is 6, traffic share count is 1
RouterB#sh ip cef 10.251.197.0 det
10.251.197.0/24, version 21421, epoch 0
0 packets, 0 bytes
via 10.252.70.188, 0 dependencies, recursive
next hop 10.252.38.70, TenGigabitEthernet3/2 via 10.252.70.188/32 (Default)
valid adjacency
Recursive load sharing using 10.252.70.188/32.
I cannot figure out why this is happening. Everything is learned via ospf/bgp. I have combed through the configs and haven't found anything. Any help would be appreciated.
