Cisco Route Configuration - need help to redirect traffic 2

[djhawthorn]

I have a Cisco 2600 currently running with 2 ethernet adaptors on IPs 10.3.8.1 (255.255.255.0 subnet) and 10.3.0.1 (255.255.255.0 subnet), routing traffic between the two. Thats working fine.

I also have a modem router configured on 10.3.8.2, which dials up onto the internet.

All the PCs on both subnets have the .1 interface of the Cisco 2600 as their default gateway. I don't want to change the routes or the gateways on the PCs (as this is a test system and they get ghosted on a regular occasion).

What I need is to have the router redirect traffic not destined to one of those two subnets, through the 10.3.8.2 modem router.

This is the current configuration of the Cisco:

==Begin Config Dump==
!
version 12.2
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Router
!
enable secret 5 $1$ryOh$scx3TDmiPRy6.RSKLfxOX.
enable password flag
!
ip subnet-zero
!
!
voice call carrier capacity active
!
!
mta receive maximum-recipients 0
!
!
interface Ethernet0/0
ip address 10.3.8.1 255.255.255.0
full-duplex
!
interface Ethernet0/1
ip address 10.3.0.1 255.255.255.0
full-duplex
!
ip classless
no ip http server
!
!
call rsvp-sync
!
!
mgcp profile default
!
dial-peer cor custom
!
!
line con 0
line aux 0
line vty 0
login
line vty 1 4
password cisco
login
!
!
end
==End Config Dump==

I am not very Cisco-savy; I know how to login, navigate and configure the Cisco IOS - just not enough to get the traffic redirection to work.

Its important for the 10.3.8.x subnet PCs to have traffic not destined for the 10.3.0.x subnet, redirected through 10.3.8.2. It would be nice (if it's easy enough to do) for the 10.3.0.x subnet PCs to also have internet access via the same modem router if possible.

Can someone modify the above config and make this work for me? Would be greatly appreciated if its not too dificult.



MCSE NT4/W2K

 

[lambent]

put a static default route on your Cisco 2600:

ip route 0.0.0.0 0.0.0.0 10.3.8.2

put a static route on your modem router:

Destination network: 10.3.0.0/24
Next hop: 10.3.8.1

And configure NAT/PAT (or port forwarding..whatever wordings) on your modem router to translate 10.3.0.0/24 and 10.3.8.0/24 to the public IP address.

 

[djhawthorn]

Bah, I figured it would be something simple, I just couldn't work out what it was.

Thanks for that.

MCSE NT4/W2K

 

[jneiberger]

As a side note, an interesting side effect of this configuration is that the router will start sending ICMP Redirect messages to users on the 10.3.8.0/24 network. The router knows that the gateway that the users really need is located on the same LAN as the users. So, it will send redirects to the end users and those machines will temporarily start sending Internet traffic directly to the modem/router.