From: Antonio Soares (amsoares@netcabo.pt)
Date: Tue Jun 19 2007 - 19:27:45 ART
Issue the "show ip ospf database" and check the router-id associated with
those equal cost routes. I would bet it is not 150.1.1.1.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Eric
Poulin
Sent: terga-feira, 19 de Junho de 2007 21:35
To: ccielab@groupstudy.com
Subject: I can't get the "distance <distance> <router-id> <acl>" to work in
OSPF with multiple equal cost routes.
Hi GS,
I don't understand what's going on, but I just can't get the "distance
<distance> <router-id> <acl>" to work in OSPF with multiple equal cost
routes. Here's the output of the routing table without any distance
manipulation:
Rack1R5#show ip route ospf
139.1.0.0/16 is variably subnetted, 14 subnets, 2 masks
O IA 139.1.11.0/24 [110/65] via 139.1.15.1, 00:11:27, Serial0/0.15
O IA 139.1.13.0/24 [110/128] via 139.1.15.1, 00:11:27, Serial0/0.15
O IA 139.1.2.0/24 [110/65] via 139.1.25.2, 00:11:27, Serial0/0.25
O IA 139.1.0.0/24 [110/138] via 139.1.25.2, 00:11:27, Serial0/0.25
[110/138] via 139.1.15.1, 00:11:27, Serial0/0.15
O IA 139.1.6.0/24 [110/139] via 139.1.25.2, 00:11:27, Serial0/0.25
[110/139] via 139.1.15.1, 00:11:27, Serial0/0.15
O IA 139.1.7.0/24 [110/139] via 139.1.25.2, 00:11:27, Serial0/0.25
[110/139] via 139.1.15.1, 00:11:27, Serial0/0.15
O IA 139.1.23.0/24 [110/128] via 139.1.25.2, 00:11:27, Serial0/0.25
As you can see, I have a single route to network 11, 13 and 2 and two
equal-cost routes to network 0, 6, 7 and 23. Routes are learned either via
139.1.15.1 (RID 150.1.1.1) or
139.1.25.2 (RID 150.1.2.2). Under the OSPF process, if I manipulate the
distance of network 11, 13 or 2 which I only have a single route, everything
works fine and I can change distance to whatever I want. Here's an example:
router ospf 1
distance 109 150.1.1.1 0.0.0.0 VLAN13
ip access-list standard VLAN13
permit 139.1.13.0
Rack1R5#show ip route ospf
139.1.0.0/16 is variably subnetted, 14 subnets, 2 masks
O IA 139.1.11.0/24 [110/65] via 139.1.15.1, 00:11:27, Serial0/0.15
O IA 139.1.13.0/24 [109/128] via 139.1.15.1, 00:11:27, Serial0/0.15
O IA 139.1.2.0/24 [110/65] via 139.1.25.2, 00:11:27, Serial0/0.25
O IA 139.1.0.0/24 [110/138] via 139.1.25.2, 00:11:27, Serial0/0.25
[110/138] via 139.1.15.1, 00:11:27, Serial0/0.15
O IA 139.1.6.0/24 [110/139] via 139.1.25.2, 00:11:27, Serial0/0.25
[110/139] via 139.1.15.1, 00:11:27, Serial0/0.15
O IA 139.1.7.0/24 [110/139] via 139.1.25.2, 00:11:27, Serial0/0.25
[110/139] via 139.1.15.1, 00:11:27, Serial0/0.15
O IA 139.1.23.0/24 [110/128] via 139.1.25.2, 00:11:27, Serial0/0.25
Now here's the bug, if I try changing the distance of any equal-cost routes,
it does not work. Here's an example:
router ospf 1
distance 109 150.1.1.1 0.0.0.0 VIA_R1
ip access-list standard VIA_R1
permit 139.1.6.0
permit 139.1.7.0
Rack1R5#show ip route ospf
139.1.0.0/16 is variably subnetted, 14 subnets, 2 masks
O IA 139.1.11.0/24 [110/65] via 139.1.15.1, 00:00:11, Serial0/0.15
O IA 139.1.13.0/24 [110/128] via 139.1.15.1, 00:00:11, Serial0/0.15
O IA 139.1.2.0/24 [110/65] via 139.1.25.2, 00:00:11, Serial0/0.25
O IA 139.1.0.0/24 [110/138] via 139.1.25.2, 00:00:11, Serial0/0.25
[110/138] via 139.1.15.1, 00:00:11, Serial0/0.15
O IA 139.1.6.0/24 [110/139] via 139.1.25.2, 00:00:11, Serial0/0.25
[110/139] via 139.1.15.1, 00:00:11, Serial0/0.15
O IA 139.1.7.0/24 [110/139] via 139.1.25.2, 00:00:11, Serial0/0.25
[110/139] via 139.1.15.1, 00:00:11, Serial0/0.15
O IA 139.1.23.0/24 [110/128] via 139.1.25.2, 00:00:11, Serial0/0.25
After seeing that, I decided to eliminate the access-list and see what
happens when I change the distance for all routes learned from 150.1.1.1:
router ospf 1
distance 109 150.1.1.1 0.0.0.0
Rack1R5#show ip route ospf
139.1.0.0/16 is variably subnetted, 14 subnets, 2 masks
O IA 139.1.11.0/24 [109/65] via 139.1.15.1, 00:05:06, Serial0/0.15
O IA 139.1.13.0/24 [109/128] via 139.1.15.1, 00:05:06, Serial0/0.15
O IA 139.1.2.0/24 [110/65] via 139.1.25.2, 00:05:06, Serial0/0.25
O IA 139.1.0.0/24 [110/138] via 139.1.25.2, 00:05:06, Serial0/0.25
[110/138] via 139.1.15.1, 00:05:06, Serial0/0.15
O IA 139.1.6.0/24 [110/139] via 139.1.25.2, 00:05:06, Serial0/0.25
[110/139] via 139.1.15.1, 00:05:06, Serial0/0.15
O IA 139.1.7.0/24 [110/139] via 139.1.25.2, 00:05:06, Serial0/0.25
[110/139] via 139.1.15.1, 00:05:06, Serial0/0.15
O IA 139.1.23.0/24 [110/128] via 139.1.25.2, 00:05:06, Serial0/0.25
None of the equal-cost routes changed, only the single route. This is a very
strange behavior, and I don't understand why. Can anyone explain me why this
is occuring?
Thanks for your input,
Eric
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