Solved: Simple routing to the Internet - Page 2

Gregg Hughes · ‎08-26-2015

Good afternoon, all!

I'm trying to complete a change in our infrastructure where we've added another subnet in a datacenter. I need to get routing from hosts behind the router out to the Internet. I can ping from any host to any other subnet host in our LAN. I can ping from the router to the Internet (8.8.8.8). However, I cannot ping from any host behind the router to the internet. I'm sure there's a simple fix that I just can't see from where I am.

Details:

The LAN side interface is 192.168.208.1/24. The WAN side is 192.168.156.7/24. I have EIGRP set up to redistribute from networks 192.168.5.0 and 192.168.156.0, auto-summary. There are no static routes.

I used an existing, working configuration as a template. I can ping to the Internet from both the router and from hosts behind the router.

The two configurations are shown as old.txt and new.txt - the new one is the configuration from the router that's misbehaving.

As you can see the configs are nearly identical. It's a really old firmware, but I don't need it to do much.

Thanks to all for looking!

Gregg

Gregg Hughes · ‎08-27-2015

Problem solved!

The issue was with the firewall north of the router in question. After we added the network south of the router into the firewall config we can get out to the Internet.

Simple, and yet not easy......btw, is there a good primer for setting up EIGRP right?

Thanks to all for looking!

Gregg

Jon Marshall · ‎08-27-2015

Glad you got it working.

In terms of EIGRP the main confusion came from the 192.168.5.0/24 entry.

With EIGRP (and other IGPs) the network statement does not tell EIGRP what networks to advertise out.

It tells EIGRP which interfaces to run on meaning any interface with an IP that falls with the network statement.

The two are not always the same ie. the network statement could actually cover multiple interfaces.

When an EIGRP speaking router advertises the IP subnets that are configured on it's own interfaces to another EIGRP device the IP subnet is derived from the interface itself ie. not the network statement. You still need the network statement if you want EIGRP to run on that interface but that is all it does.

You don't have any interfaces from the 192.168.5.0/24 subnet so that statement isn't doing anything.

I'm also assuming there are no other routers running EIGRP on the 192.168.208.0/24 subnet or else you would need a network statement for that as well.

So it's not that it isn't working it's just that seeing the 192.168.5.0/24 was confusing especially as you said in your original post that you were redistributing from that subnet which you aren't as far as I can see.

Jon