[cisco-voip] weighted EIGRP routes

[Lelio Fulgenzi]

OK. In this case, the "interface" that connects the routers to the VG224 are not a physical interface, but a logical VLAN (or sub) interface. 

do I put the bandwidth/delay command on the gi2/0.201 sub-interface or on the switch's physical interface? 



on the router: 

interface gi2/0 
desc Service Module 
interface gi2/0.201 
encap dot1q 201 
ip address 192.168.201.1 /24 

on the internal switch: 

interface gi0/1 
vlan 201 
desc VG224 
interface gi0/18 
desc trunk to router 
allowed VLANs 201 (among others) 

on the vg224: 

interface fast0/0 
desc link to router 
ip address 192.168.201.2 /24 






--- 
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) 


----- Original Message ----- 
From: "Brantley Richbourg" <Brantley.Richbourg at MMICNC.COM> 
To: "Nate VanMaren" <VanMarenNP at ldschurch.org>, "Lelio Fulgenzi" <lelio at uoguelph.ca>, "cisco-voip voyp list" <cisco-voip at puck.nether.net> 
Sent: Thursday, March 18, 2010 10:33:02 AM GMT -05:00 US/Canada Eastern 
Subject: RE: [cisco-voip] weighted EIGRP routes 


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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