Can you guys tell me exactly what you were able to do with IOS15 that was not available previously? I have a router that receives a subnet from two different neighbors and it receives this subnet on the same interface. It also happens to be an external route. This gives me two equal path routes and I want to prefer one neighbor over the other.
I was under the impression that offset-list only allows standard ACL so I can't specify the source router. I then tried to use "distance" but I realized that it doesn't have any effect on external routes. So I am kind of stuck here.
This router is currently running 15.5 so I was hopeful that there where new options for me but if there are I am not finding how to use them. It seems to be that IOS15 behaves the same as 12.x versions.
That is the command,
you must enter this command in router configuration mode as follow.;
R1(config)#router eigrp 10
R1(config-router)#distance eigrp xx yy
where xx representes the new value of internal administrative distance and yy representes the new value of the external administrative distance.
You should be more specific of what you're trying to achieve. If you got a route from External EIGRP with an AD of 170 and the same route from OSPF with the AD of 110, then you would want to influence that specific route that the OSPF router is sending you, so then your router would prefer the normal route through EIGRP with the AD of 170, instead going crazy through OSPF.
Here's how you do that, go on the router that have to take the EIGRP route instead of the same route learned through OSPF with a better AD, so, go on and configure the following:
router ospf 1
distance 171 184.108.40.206 0.0.0.0 1
access-list 1 permit 192.168.1.0 0.0.0.255
So, just to expalin what this configuration means, you are going to your OSPF process on that router and say to him, when you get the route of 192.168.1.0/24 from my neighbour with which i run OSPF, assign to his advertised route of 192.168.1.0/24 a Administrative Distance of 171, which is greater than 170 and lower than the initial one of 110. And below that is the access list, which is matching the specific network you want to assign that AD of 171.
Now you'll have a AD of 170 for the main path through EIGRP and a redundant path with the AD of 171 through OSPF.
also, if you have an internal route vs and external eigrp route, even if you set admin distance, internal route will alway be preferred. So usually if im in an environment where i redistribute from bgp, and say have a backhaul connections between sites where its all eigrp (perhaps dmvpn backup) i always redistribute connected making everything external, that way if i learn the route from my mpls router from bgp and then learn it from my dmvpn hub, i can simply modify the delay and chose mpls over dmvpn.