Re: Network config for isolating WiFi

Hi Doug -

On Sat, 1 Mar 2008 21:25:32 -0500, "Douglas Handy" <dhandy@xxxxxxxxx>
wrote:

All that's needed is ARP packets sent for each configured IP address,

advertising that IP address for the NIC's MAC address. The MAC
address controls the actual packet flow for ethernet.

OK, I must be having a duh-g moment here. Physically, how would the network
be wired?

I haven't been reading the thread closely, I just jumped in because I
know from personal experience it's quite possible to have multiple IP
addresses on a NIC.

Also, I don't have any actual hands on experience with setting up
wireless.

With those caveats, I'll throw up, err... out, a few things anyway.
<G>

Currently, it is simply:

( internet ) -- ( firewall & DHCP ) -- ( switches ) -- ( 520 & other
devices )

Now we add the WRT and wireless to the mix, using a different network base
address and subnet mask to isolate the traffic.

Where does the WRT attach to the network? From the WAN side to the regular
LAN switches? From the switch side of the WRT?

The WAN side of the WRT to a LAN switch.

I did find this page which describes how to add multiple static IPs under
WinXP, provided they are in the same logical network but on different
subnets:

http://www.itsyourip.com/networking/how-to-add-multiple-ip-address-in-windows-2000xp2003/

I don't know what the heck they mean by being in the same logical
network but on different subnets. As I see it, a subnet *is* a
logical network. (Unless you split a subnet into multiple subnets
with some devices being defined within the large subnet and others
within the smaller subnets. IMO, that's a situation just looking for
problems. If you want the smaller subnets, put everything in the
smaller subnets.)

On the [unofficial] RH9 Linux box that I set up at work to provide
some special routing functions, there is one NIC with at least five IP
addresses, three in the 10.100.8.0/22 network (our main LAN), one in
192.168.0.0/24, and one in 192.168.73.0/24. Two of those in
10.100.8.0/22 do double NATing (source NAT as well as destination
NAT), one to each of the 192.168 subnets.

So using that, can I just assign the PCs static IPs in each subnet, and add
the WRT to the regular LAN switch?

Yes, but the PCs can also have DHCP-assigned addresses from your main
DHCP server.

What about DHCP to the wireless handhelds? Won't the network be confused by
having two DHCP servers? Or can I avoid that by using the WAN side of the
WRT?

By connecting the WAN side of the WRT to the LAN, the LAN DHCP server
shouldn't ever see the wireless DHCP requests.

Should the showroom PCs then be attached to the WRT switch, or the regular
LAN switches?

The regular LAN switches. If I'm understanding correctly what you're
doing, because you have a separate router between your LAN and the
internet, nothing should be connected to the switch side of the WRT.
The only things on that side of the WRT should be the actual wireless
device.

I also don't see in this situation where you would need multiple IP
addresses on a NIC, unless you want to run the WAN side of the WRT in
a different subnet from the main LAN. If you want that, then the
firewall would need to have two IP addresses, one for the main LAN and
one for the WRT.

Ken
Opinions expressed are my own and do not necessarily represent the views
of my employer or anyone in their right mind.