I want to make a computer having linux as router

It would allow two subnets within a LAN to communicate with each other

one subnet is of 172.x.x.x while the other of 192.x.x.x

is NAT the solution?

if not then plz tell me which tools should be used to achieve this

no NAT should be required if you i understand your configuration, ie, the computer is connected to two separate LAN's and you want linux to route traffic between them, it's piece of cake:
just make sure your linux box has ip forwarding and proc filesystem built into the kernel and ensure that it has route's to all the subnets (check route command) and that you can ping both subnets from the linux router. then just:

echo "1" > /proc/sys/net/ipv4/ip_forward
(this enables ip forwarding, ie. routing)

and set the linux router's ip address as gateway to the other subnet (or just default gateway if you don't have other network connectivity) on each machine of both subnets (or just use dhcp or whatnot) and you should be good to go.

Thankz for your reply

So would this configuration allow the computers of 172.x.x.x subnet to communicate with the computers of 192.x.x.x subnet via this linux box?

yup, and also the other way around. ie 172.xxx <-> 192.xxx
you can also use iptables to firewall some machines out for example or add NAT:ting to it, or whatever you want.

hey guys
just started posting on these forums and i've just started using linux so... bare with me.
okay, here's the situation: PC1 - router, PC2 and PC3, both in different subnets. to configure my computer as a router, here's the script that i run:

#!/bin/bash
echo 1 > /proc/sys/net/ipv4/ip_forward

ifconfig eth0 192.168.10.36 netmask 255.255.255.0
ifconfig eth0:1 192.168.10.110 netmask 255.255.255.0

route add -host 192.168.10.36 dev eth0
route add -host 192.168.10.110 dev eth0:1

route add -net 192.168.10.32 netmask 255.255.255.0 gw 192.168.10.33
route add -net 192.168.10.96 netmask 255.255.255.0 gw 192.168.10.97

I have to do this in class, and yes, that is the right netmask because we were given 192.168.10.0 Class C address range to play around with. As far as I know, this script should give address 192.168.10.33 and 192.168.10.97 direct connection (they should be able to ping each other) but for some reason, they can't. And I'm lost now. Please help. Thanks