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New Member

Policy-Based Routing Dilemma

Hi All,

I have 2 serial links to my data center that I want to do policy routing

across. The data from interface ethernet 0 will be routed out serial 0,

and the data from ethernet 1 will be routed out serial 1. The problem

that I expect to happen is at the data center. How do I ensure that the

data bound for ethernet 0 from the data center will be sent on the same

link that it was sent on (and vice-versa). I would like to do this without

manipulating the data center routers. (I suspect I'll have to force eigrp

routing updates for these networks out their perspective serial interfaces,

but I don't know how to do this.)

e0 - - s0 ---- RouterB

RouterA

e1 - - s1 ---- RouterC

Routers B and C are on the same LAN network at the data center and I don't

want the data bound for e0 come from RouterC, or if going to e1, it shouldn't

go thru RouterB.

Any help is appreciated,

Bob

4 REPLIES
New Member

Re: Policy-Based Routing Dilemma

Hi Bob

The solution to your problem is depending on what ways you have to influence the routing tables on Router B and Router C. You wrote that you have EIGRP running between A, B and C. I am not an EIGRP pro, but you might start with:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios100/eigrp/58898.htm#xtocid1179315

and

http://www.cisco.com/warp/public/105/34.html

"distribute-list access-list-number out [interface-name | routing-process | autonomous-system-number] " should do the job:

Say:

E0: 192.168.1.1/24

E1: 192.168.2.1/24

RouterA:

access-list 1 deny 192.168.1.0 0.0.0.255

access-list 1 permit any

access-list 2 deny 192.168.2.0 0.0.0.255

access-list 2 permit any

router eigrp 1

network <...>

distribute-list 1 out s1

distribute-list 2 out s0

Fritz

New Member

Re: Policy-Based Routing Dilemma

Thanks, Fritz. This looks like a solution for me. -Bob

New Member

Re: Policy-Based Routing Dilemma

Hi.

Fritz's solution will work, but if you need some redundancy you can get into trouble. Imagine that one of the serials goes down... You will loose conncectivity to the network that was being advertised on that serial!

It would be much better if you could manipulate routing metrics at the datacenter router.

Rgds,

NM

Gold

Re: Policy-Based Routing Dilemma

This would work, but I'd suggest allowing a default or larger prefix covering all the routes through both serials, so that if one fails, the other can pick the traffic up.

Russ

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