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Jay Sundee
Beginner

Traffic shaping via EIGRP

Hello,

I have set up an EIGRP network in which there are two routers, each with a T1 circuit, that each need to be the primary path for different subnets.  Please see the attached drawing.  I need to ensure that Router A needs to be the primary path for the 172.16.10.0 network and Router B needs to be the primary for the 172.16.20.0 network.  But, in the event that one circuit goes down, the traffic can fail over to the other router.

Can someone help me with how EIGRP can be manipulated for this?  Would I use route maps on the distro switch?  Any configuration examples would be great.

thank you,

Jay                 

4 REPLIES 4
John Blakley
Advisor

Jay,

What's on the other end of the routers? Is it an ISP or p2p with another site? If we assume that you have 2 different ISPs - worst case scenario - you'll have to configure nat on both of the routers for both subnets to account for a single circuit going down. The other thing that you'll have to account for is what happens when that circuit goes down. You'll probably want a floating static default route pointing to the other router in the event that the circuit does go down. Policy maps will be the best way for you to direct traffic per source subnet to the appropriate router.

So, the questions that I have are:

  • Do you connect to an ISP on each of these routers which requires nat or is it another site on the other end?
  • Do you have a static default route now that points to the other end?

HTH,
John

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HTH, John *** Please rate all useful posts ***
cadet alain
Advisor

Hi,

if you want to influence traffic flow according to source address you need to use PBR.

Can you post your switch config.

Regards.

Alain

.

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Jay Sundee
Beginner

Hello,

Thanks for your replies.  The other end of each circuit is T1 p2p to another site.  Each circuit on the other side also has it's own corresponding router, basically mirroring the original drawing.  There is no static default routes configured outbound to the other site, but rather letting EIGRP decide on the path.  I can try and provide a sanitized config, but it's very basic as far as EIGRP is concerned.

From the research I have done so far, it does seem like policy based routing is what I'm looking to implement for this.  I'm just not sure by which parameters I need to manipulate to influence the path (delay or bandwidth?)

Any additional information would be greatly appreciated.

Thanks,

Jay

Jay,

You'll want to use pbr to influence the outbound traffic like you're wanting. The only other suggestion that I have is to make sure that you have at least 2 routes in your eigrp topology table for each remote subnet. The problem that you could run into is that if router b, for instance, has a single route pointing to the other side of the p2p link and the link were to go down, router b would need to query its neighbors for a successor. If it can't find one, router b would drop traffic because the route is now out of the routing table.

HTH,
John

*** Please rate all useful posts ***

HTH, John *** Please rate all useful posts ***