Adjust EIGRP metric on routes received from neighbor

[kejones]

Have a 3845 router connected to diverse 6500 switches on a common VLAN using 2 LAN ports (FE0/0/0 and FE0/0/1). I want to prefer routes from the neighbor connected via the FE0/0/0 (VLAN 201) interface. I increased the delay on the FE0/0/1 (VLAN 201) interface, but still have equal-cost paths over the VLAN 201 interface. Is there an easy way to adjust the metric on routes learned from one neighbor on a common VLAN segment?

[Richard Burts]

Keith

When I want to manipulate the metric of received EIGRP advertisements I have had good success using offset-list. The offset list can be applied inbound or outbound per interface, and can us an access list to identify routes that you want to change if you need to be that granular.

So I suggest that you take a look at using offset-list and see if it solves your requirements.

HTH

Rick

[kejones]

Hi Rick,

would the offset-list be applied to the router's VLAN interface or physical interface, and if the physical interface, why wouldn't a delay statement work if applied to the physical interface?

Could the offset-list be set for all routes received from an individual neighbor on the common VLAN?

[Richard Burts]

Keith

I find your description of using 2 LAN ports (Fa0/0/0 and Fa0/0/1) on a common VLAN to be very confusing and in my experience it does not work unless you are doing something like IRB. So I am having a hard time deciding how to answer your question about where the offset list would be applied. So I will just say that the offset list is applied on the layer 3 interface of the router where the EIGRP neighbors are connected.

Perhaps if you posted the router config we might understand better what is being done and what alternatives would work best.

HTH

Rick

[Richard Burts]

Keith provided me some information off list which was very helpful. I understand why he chose to provide some of this off list and I choose to respond here so that others may see it and potentially benefit.

One important aspect that I had not understood is that this router has a switch module and the access to the VLAN was through 2 interfaces in the switch module. I had been thinking in terms of the usual router LAN interfaces where connecting both of them in the same VLAN is problematic. But two interfaces of the switch module in the same VLAN is no problem. And it helps to explain why using the delay command did not have the result that he hoped for. I gather that he was applying the delay on the switch interfaces (which are configured as access ports and therefore layer 2 interfaces not layer 3. But EIGRP only looks at the delay of the layer 3 interface on which it is running. EIGRP has no visibility about the layer 2 interfaces which connect to the neighbors.

There is an alternative which Keith may try. It is using the distance command to change administrative distance of received routing updates. I found a tech note which describes changing the administrative distance of a specific neighbor. Check this link for discussion and example:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800c2d96.shtml#changedistR2

I have not used this feature and can not say how it will work. But the documentation sounds promising.

HTH

Rick