EIGRP and Static Route

naparrott · ‎11-25-2008

Hello,

I have a question to anyone who feels obliged to answer.

Can I have a static route while running EIGRP? I believe I can, but want some reassurance. Here is my scenario. I have a vlan that is "trunked" that allows all vlans to flow between to "separate" halfs of a network. The problem I am having is I want to route 1 particular vlan separate from that. Obviously the EIGRP that is implemented has 2 network statements.

router eigrp 11

network 123.13.0.0

network 123.133.254.0 <-- the vlan I want to separately route is currently coming down on this network.

Dees this make sense?

My question is could I make a static route on that L3 device like this?

ip route 172.18.120.0 255.255.255.0 10.1.1.1 <-- next hop (layer 3 box)

Thanks

Nick

tcordier · ‎11-25-2008

I am not sure what you need to achieve, or how your network looks like, so I may misunderstand your question.

You can use different routing protocols simultaneously. In your case, you can use EIGRP and static (which you can consider a routing protocol in this context) together in the same network, or on the same device. Your L3 device will select the preferred source of routing information based on the administrative distance (AD) of the routing protocol. EIGRP has an AD of 90 (internal routes) and static has an AD of 1. If you L3 device sees the same route from EIGRP and static, it will select the static due to the lower AD. So, yes, you can "overrule" EIGRP by adding a static for a specific network.

This is the short version, I hope it makes sense. If you search for "administrative distance" on cisco.com, you will find more information and details.

- thomas

naparrott · ‎11-25-2008

OK thanks, this is along the lines of what I was thinking. But if I want to send the traffic only one way to one box, is it true that I need to have the static route in every L3 box? Or just the ones that are sending to the "final destination" L3 box? Do I need the static route in the "final destination" L3 box?

Thanks for your help

Nick

tcordier · ‎11-25-2008

The route to the destination must be known on each router along the way (either by a static route, and a dynamic entry in the routing table (EIGRP, for instance). Additionally, each route along the way, and the final destination router must have a route back to the source. IP routing works "hop-by-hop".

What do you mean by one way? One path to the destination, but another path from the destination back to the source?

- thomas

naparrott · ‎11-25-2008

By One way I mean I am trying to send traffic to a final destination (aka a Server) from one direction. I think I understand what I need to do. I will post back here shortly and let you know.

Thanks again