From: Edwards, Andrew M (andrew.m.edwards@boeing.com)
Date: Mon Aug 23 2004 - 20:18:02 GMT-3
All,
I'm struggling with getting this to work in a development environment.
I have four routers in a single OSPF area. There is connectivity
between all routers in a full mesh. (e.g. distribution to core
configuration). So, from any one core router there are 2 equal cost
routes to all distribution subnets.
I have setup the distribution routers to split the load on even and odd
subnets. I have fixed the spanning tree root bridge selection and HSRP
to reflect this in the distribution layer.
What I want to do now is setup the OSPF process on the core routers such
that even routes prefer router 10.10.10.25 and odd routes prefer router
10.10.10.9.
I have decided to try and use distance for this:
So, I match the source router-id for the 10.10.10.25 router and
increment the distance of odd routes sourced from it. This should leave
even routes at default distance.
Next, I match the source router-id for the 10.10.10.9 router and
increment the distance of even routes sourced from it. This should
leave odd routes at default distance.
What I expect is that the even routes would prefer 10.10.10.25 and odd
routes would prefer 10.10.10.9. What I get in the routing table though
is weird.
I end up AGAIN with two equal cost paths to the either subnet (even or
odd). The cost is the same as before (expected) and the distance for
BOTH sources has incremented (not expected).
Show ip route
10.10.100.0/24 [112/2] via 10.10.10.9
[112/2] via 10.10.10.25
Maybe I'm not implementing the distance command effectively or there is
another way... I'm trying to stay away from PBR at this point and use
the routing protocol... any ideas?
Configs below:
------------
CorerouterB:
Int g1/1
Ip address 10.10.10.10 255.255.255.248
Int g1/2
Ip address 10.10.10.26 255.255.255.248
Router ospf 1
Router-id 10.10.10.26
Network 10.10.10.0 0.0.0.255 area 0
Distance 112 10.10.10.9 0.0.0.0 20
Distance 112 10.10.10.25 0.0.0.0 10
Access-list 10 remark match odd subnets
Access-lsit 10 permit 0.0.1.0 255.255.254.255
Access-list 20 remark match even subnets
Access-list 20 permit 0.0.0.0 255.255.254.255
DistributionrouterA:
Int g3/1
Ip address 10.10.10.9 255.255.255.248
Router ospf 1
Router-id 10.10.10.9
Network 10.10.10.0 0.0.0.255 area 0
DistributionrouterB:
Int g3/1
Ip address 10.10.10.25 255.255.255.248
Router ospf 1
Router-id 10.10.10.25
Network 10.10.10.0 0.0.0.255 area 0
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