[cisco-voip] weighted EIGRP routes

Brantley Richbourg Brantley.Richbourg at MMICNC.COM
Thu Mar 18 10:33:02 EDT 2010


 If you want to change the metric calculations for an EIGRP route, you have to modify parameters that EIGRP uses to calculate the feasible distance. The bandwidth and delay commands on the interface(s) in question can accomplish this.  You can verify by looking at the "show ip route" and you should see the next hop as the one for your primary path. "show ip eigrp topo" command will also show how feasible distance was calculated for each upstream router.

If you change the bandwidth or delay on the interface that belongs to the upstream router, that will change the "Reported Distance" sent to the downstream router, which will in turn change the "weight" on that router to the upstream router.
________________________________
From: cisco-voip-bounces at puck.nether.net [cisco-voip-bounces at puck.nether.net] On Behalf Of Lelio Fulgenzi [lelio at uoguelph.ca]
Sent: Wednesday, March 17, 2010 9:30 PM
To: cisco-voip voyp list
Subject: [cisco-voip] weighted EIGRP routes

Any pointers on how to tell a downstream EIGRP neighbour to weigh one route better than another? Do I put the weight on the downstream neighbour to say EIGRP routes coming in on one interface should be weighted more heavily? Or on the upstream router to push down the weights?

Basically, what I have is this:

________________________________
        +-----------------------+
        V                       V
3945 -> switch -> VG224 <- switch <- 3945, where switch = SM-ESx-16

(view with fixed font)
________________________________

Two 3945s with service module ethernet switches which connects to the two VG224 ports. All routing is done on the router and the switch provides layer two connectivity. A port channel group between the two switches allow the routers to communicate HSRP keepalives. The VG224 is an EIGRP stub, and the two upstream routers send out only default routes to the VG224 (that's all I want).

Everything is working great. Except for the fact that the two upstream routers are equal weight. This means that when the VG224 is talking to the active HSRP address, it's going back and forth. Since the layer two link is up between the routers, it still works, but not ideal. Bad things happen if the link between the routers goes down - split brain!

Any pointers?




---
Lelio Fulgenzi, B.A.
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Cooking with unix is easy. You just sed it and forget it.
                              - LFJ (with apologies to Mr. Popeil)



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