IPs on home network

Question

I have a Linksys router and a Belkin wireless router at home. The Linksys router is connected to cable modem and two computers, as well as to the Belkin wireless router.

A 3rd computer is connected to the Belkin router through Wifi.

The IP addresses of the computers connected to Linksys are 192.168.1.101 and 192.168.1.102. The IP address of the Linksys router on LAN is 192.168.1.1.

The IP address of the Belkin wireless router is 192.168.2.1(based on the 3rd computer's routing table) and the IP address of the 3rd computer is 192.168.2.5.

If I ping 192.168.1.101 from 192.168.2.5, all are well. However, if I ping 192.168.2.5 from 192.168.1.101, Destination Host Unreachable.

Why?

Answer 1

that would be because the default gateway on your 192.168.1.101 machine is 192.168.1.1. So when you ask to send traffic to a network that your not on directly it sends it to the default gateway which in this case is 192.168.1.1. So the problem is that 192.168.1.1 doesn't know how to get to 192.168.2.0/24 network.

If the Belkin is connected to the Linksys it should also have a 192.168.1.x address? Once u know this you could fix this 1 of 2 ways. Add a static route on 192.168.1.1 that says to get to destination network 192.168.2.0/24 the Gateway or next hop is 192.168.1.x(belkin). You should be able to add this somewhere in the Linksys gui. Look for "routing" in the menus. The other option is to just add a static route to Windows on your 192.168.1.101 box.

route add 192.168.2.0 MASK 255.255.255.0 192.168.1.x

Hope this helps.

Answer 2

You have what we in the networking business call a "black hole". Basically you can ping from the 2.x network to 1.x because the 2.x computer asks the belkin router (the computers gateway to the outside world), the belkin router might know, but is probably going to try and arp to find the 1.x computer address. The computer responds to the belkin router, which then forwards back to the 2.x computer.

The other direction the 1.x computer asks the linksys router where it is and (unless you have set up a route to 192.168.2.0/24 network if the router supports it) the linksys router has no idea. Now a 192.168.2.x address is a private class C (which can't be routed accross the internet) So the linksys router might just give up then, or it might try to send it up the chain (the linksys router asking ITs gatweway) at some point they are going to stop trying to resolve the private address and return back destination unreachable.

Perhaps you installed the belkin router solely as a way to isolate the wireless clients, not a bad practivce, You're either going to need to add the route from the linksys router to the 2.x network (may not even be supported on home devices without custom firmware) you would also need to make sure that NAT is disabled on the belkin router.

To have the networks talking directly (not seperate networks) , you are going to need to do a few things. Change the way that the belkin is connected. You're probably in the WAN/Uplink/Trunk/Modem ports on the belkin, change that to on of the regular/LAN/Downstream ports. You would also need to turn off the DHCP server (or configure it as a relay) and change your address on the belkin to the same range as the linksys (I'd suggested belkin is 1.2 since linksys is 1.1) This woulld allow traffic to still be resolved through the linksys router, DHCP is handled by linksys, belkin may be a wireless AP, but DHCP should still be through linksys for the wireless clients. Basically we changed belkin from being a SUB network to an Access point and switch on the same network.