Basic Router Set-up

Unanswered Question
Mar 7th, 2008

Hi i am a newb.

I have the following setup, all

Laptop(<>Catalyst 2970 (GE0/23<>Cisco 1811 ((FE0 (FE1

This is all behind a firewall off the Cat 2970. The Catalyst 2970 has been working like a champ since before I started this job. The Cisco 1811 is new. I was given it and told to put a small stub network on it ( I configured quite a bit on the 1811 but am stumped on the static routing.

Number 1. From the laptop ( of coarse I can ping the Cat 1811 FE0 (, but not FE1 ( Do I need to configure something on the Cat 2970? I didn't think I needed to since its a switch.

2. Or is I just need to configure a static route on the 1811. From the 1811 cli I can ping the laptop and both FE0 and FE1 and also a desktop ( plugged into FE1.

Any consideration of my problem will garner provider cheers of good luck to his or hers future success, health and offspring.


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Jon Marshall Fri, 03/07/2008 - 16:09


What is the default-gateway on the laptop set to ?

It needs to be set to the fe0 interface of the 1811 ie.

Also the desktop off fe1 needs to have it's default-gateway set to



zitherfilter Mon, 03/10/2008 - 06:27

Here is a little more info on my setup:

SonicWall Firewall ( attached to our ISP T1 router.

A Catalyst 2970 (GE0/23 attached to the LAN port of the SonicWall FW.

My laptop ( and various other equipment attached to the Cat 2970. The default gateway for the laptop and everything on the network is the SonicWall Firewall.

This all works fine.

I am now adding a new Cisco 1811 ((FE0 to a port on the 2970. The 1811 will host a new network,

- (FE1

Can you have a second default gateway? Is there something on the Cat 2970 that needs adjusted?



rwyates_2 Mon, 03/10/2008 - 06:49

You can do one of two things.

The Sonic wall does not know anything about the new subnet. You would have to configure a inside route on the sonic wall so it knows about the new subnet. I am not sure if the Sonicwall will allow the ip re direct out the same port.

The other option is to change the default gateways of you computers to the new 1811. Then you would need to put a default route of

You would have to change the default gateways on all PC's

Jon Marshall Mon, 03/10/2008 - 06:50


If the default-gateway is the sonicwall you could add a route to the network on the Sonicwall pointing to the 1811 fe0 interface. But it depends on youe sonicwall firewall. Some firewalls do not like routing traffic back out the same interface it came in on.

Other options is to set the default-gatway of your clients to be the fe0 interface on the 1811 rather than the sonicwall and then have a default-route on the 1811 pointing to the sonicwall interface


zitherfilter Mon, 03/10/2008 - 08:31

I added a route on the Sonicwall Firewall of, which now allows me to ping the 1811 FE1 interface ( from a laptop on

Plugged into FE1 of the 1811 I have a desktop with DHCP'd IP of From it I can ping but not FE0 (

or anything beyond.

rwyates_2 Mon, 03/10/2008 - 19:42

You have to make sure the PC has a default gateway of the 16.1

vaisharm Mon, 03/10/2008 - 06:59

Hi Zith,

You can create two separate VLANs (VLAN1 & VlAN2) for 10.16.6.x and 10.160.16.x networks and use your new Cisco 1811 to do the inter-vlan routing. Basically, you can implement router on a stick model where in the devices in each VLAN can use a sub-interface on the router as their default gateway.

Configuring InterVLAN Routing and ISL/802.1Q Trunking on a Catalyst 2900XL/3500XL/2950 Switch Using an External Router




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