Wireless Network Design

I set up a wireless router in my upstairs home office (providing good coverage for the second floor) and a second one downstairs in the living room where signal strength is too low to be useful. There are probably lots of different ways to do this but I would like feedback on the theoretical as well as practical pros and cons of two approaches:

1) One wired network ( connecting the LAN port of the DSL modem and the WAN ports of both wireless routers. Each router would give out their own small pool of DHCP addresses, upstairs and downstairs.

2) The wireless router upstairs would be the only one with DHCP enabled and would connect to the one downstairs via the LAN-side switch. In effect, this turns the downstairs router into a bridged access point.

Are both approaches equally valid?

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Bob Simon
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this one stops you sharing files / printers etc between devices attached to the 2 routers.

It is difficult to connect if your modem only has 1 Ethernet port.

it also breaks down completely if the provider only allows you a single WAN IP address at a time....

this is more common (mainly because SOHO routers are cheaper than dedicated access points). You are using the LAN only box as a switch / access point only. Some boxes have "AP only" mode this as a setup option.

no - 1st one doesnt work if you only get 1 address.

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I hooked up my two routers as per the second design and everything works except roaming. I set the SSID and WEP keys the same and put one router on channel 1 and the other on channel 6. When I go from my upstairs office to the living room, the signal strength meter displays zero or one bar but XP does not switch to the downstairs AP unless I disable or disconnect the wireless connection. When I re-enable or re-connect, I get five bars. Can this switchover be made to occur automatically?

Also, I don't understand your comment that my first design won't work because

My ISP provides a single public static IP address to the WAN port of the DSL modem. But since this modem does NAT, it should be able to handle mulitple inside hosts with private addresses up to the limit of its ability to handle translations without excessive delay. Right?

-- Bob Simon Please remove Xs from domain for direct replies.

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Bob Simon

Are you able to configure the DSL modem ?

If for example the DSL modem is setup to only NAT 192.168.0..0/24 then you might have an issue ....

If you can control its configuration so that it will NAT, then you should be okay
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The modem is a Motorola/Netopia 2210-02. Motorola tech support said it's been customized per ATT specs with some functionality stripped out. I am able to configure it via the web interface plus via telnet, which offers additional configuration granularity. There is no manual available but the CLI offers help screens and command options. I only see four NAT features: mode -- NAT default server mode mode (off) [ off | default-server | ip-passthrough ] address -- NAT default server IP address dhcp-enable -- NAT IP Passthrough DHCP enabled host-hardware-address -- NAT IP Passthrough host hardware

Why would it be useful for the modem to be able to NAT for more than one class c subnet? Wouldn't the following scenario work?

DSL Modem WAN: public static LAN: Def GW: WAN port NAT for to public static IP

Wireless Rtr 1 WAN: LAN: Def GW: NAT for to

Wireless Rtr 2 WAN: LAN: Def GW: NAT for to

Both routers would provide DHCP addresses for their respective wireless clients. I presume roaming would not work because the client would need to obtain a new IP address. But roaming doesn't work now anyway as I mentioned yesterday.

If I'm missing some key point about network connectivity that requires NAT for, I sure wish that someone would enlighten me. Bob

Reply to
Bob Simon

OK - sounds like your "modem" is actually acting as a router.

However - sharing between the 2 routers with default config will not work (since you cannot initiate a TCP connection on 1 and deliver to the other if you have NAT on each).

Try turning off NAT & DHCP on both of your routers and let the modem (router) do it.

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I don't intend to use the default config. Other than that, do you see a reason that the first design will not work?

Is there some reason that a wireless router and the DSL modem cannot both do NAT?

Reply to
Bob Simon

Double NAT'ing is generally considered troublesome but you can give it a try of course

You should also determine if the wireless routers can be configured as bridges and just use for the entire setup

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if you can disable NAT, then you should be able to get the clients on W rtr 1 and w rtr 2 to talk directly.

OK. if rather than NAT these can work as real routers then you may be able to make it work - but the modem would need to handle static routes, RIP etc, since your LAN would comprise 3 subnets.

A better way (especially with only a few devices) is to structure it as a single subnet.

But if the wireless routers just use no NAT, no routing and you have DHCP for all devices from the "DSL modem" then a device should be able to move across the 2 wireless links using the same IP address.

So if the address stays the same, you should be able to get roaming to work.

hook a LAN port on each router to the modem. Disable NAT / DHCP on each router (or run them in "AP mode" if they support it). Do not connect to the WAN ports on the routers.

if you remove 1 layer of NAT you end up witha system with a single "LAN" and IP subnet, spread across the modem + 2 routers.

once you have that the connectivity between your devices is unrestricted, and you have a chance to sort out roaming.

Note - if you want roaming to work, you need:

  1. the same SSID / key phrase / wireless encryption mode on both wireless routers.
  2. devices where the wireless driver understand roaming (and implements it correctly) - lots of flakey / broken drivers out there...
  3. A LAN that handles the logical move of a MAC address - this is functions in the bridging within each wireless router + in the modem.

good luck

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