Weird Routing problem

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Oct 9th, 2007
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Hello all,

I?m having a very weird routing problem. I have a remotes site that has a T1 going into it and as a backup we have a VPN over the internet via a PIX at the remote site.

The T1 from the site terminates on 7206-2 (Refer to attached Pic) and the VPN terminates on 7206-1. My network uses EIGRP as our primary routing protocol. On 7206-1 I have a weighted Static (which is redistributed via EIGRP to the rest of the network) pointing the traffic to 10.220.38.0/24 across the VPN (weighted at AD=254), should the route from the T1 on 7206-2 falls out of the routing table. This works fine? sorta. I had to put a distribute list on 7206-3 because it was causing routes for this particular network to flop around should the failover be initiated.

Now that the back story is over, here?s the weird part. When the T1 is brought back up, the Static route stays in the routing table. The route learned via EIGRP is ignored unless I go into 7206-1 config and remove the route (no ip route 10.220.38.0 255.255.255.0 fa0/0 254) then re-add it. I checked the Eigrp Topology for the offending network on 7206-2 and found the following:

7206-XO2#sh ip eigrp topology 10.220.38.0/24

IP-EIGRP (AS 10): Topology entry for 10.220.38.0/24

State is Passive, Query origin flag is 1, 2 Successor(s), FD is 33280

Routing Descriptor Blocks:

10.2.10.18 (FastEthernet0/1), from 10.2.10.18, Send flag is 0x0

Composite metric is (33280/30720), Route is Internal

Vector metric:

Minimum bandwidth is 100000 Kbit

Total delay is 300 microseconds

Reliability is 255/255

Load is 10/255

Minimum MTU is 1500

Hop count is 2

10.2.10.14 (FastEthernet0/0), from 10.2.10.14, Send flag is 0x0

Composite metric is (33280/30720), Route is Internal

Vector metric:

Minimum bandwidth is 100000 Kbit

Total delay is 300 microseconds

Reliability is 255/255

Load is 12/255

Minimum MTU is 1500

Hop count is 2

10.2.155.214 (Serial2/0/28:0), from 10.2.155.214, Send flag is 0x0

Composite metric is (2221056/28160), Route is Internal

Vector metric:

Minimum bandwidth is 1500 Kbit

Total delay is 20100 microseconds

Reliability is 255/255

Load is 1/255

Minimum MTU is 1500

Hop count is 1

The routes are learned from the backbone switches as well as across the T1, but the routes learned from the backbone switches is being preferred. What would I have to adjust to make it prefer the route learned from the serial interface? I tried to artificially lower the delay on the serial, which lowered the metric, but not enough. Any ideas how to remedy this issue? Thanks in advance!




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