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How to bridge two wireless routers for a single network?
September 1, 2007 8:51 AM   Subscribe

I'm thinking of using two Wireless LAN router-switches from two different manufacturers in different rooms to create a single network for a multitude of devices. How is this done (see extended explanation)?

My current setup relies on a Buffalo WHR-G54S with the excellent open source DD-WRT firmware flashed as a replacement for the shoddy original. It's in the bedroom, connected to three machines with an ethernet cable. A fourth ethernet cable runs to the living room to the Xbox, and this is something I want to get rid of.

In addition to the Xbox, the living room houses a Nintendo Wii and the odd laptop, all of which connect to the wireless LAN. An unconnected PSTwo sits there as well.

Lately I've been eyeing Apple's new Airport Extreme with its gigabit ethernet ports. Since I've already got a wireless router, I thought maybe I could get rid of the annoying room-to-room cable with it. Here's the planned setup:

Airport Extreme is the main router in the bedroom. It connects with wires to the three machines there, and creates a 802.11N Draft 2.0 wireless network secured with WPA, let's call it MyWLAN.

In the living room is the Buffalo router. It bridges to MyWLAN and connects as an ethernet switch with standard 100Mbps wires to the Xbox and the PSTwo.

A couple of questions:

1) Is bridging two discrete routers in this manner possible? The Buffalo need not provide wireless connectivity to any clients (the signal from the bedroom AP reaches the wireless devices in the living room just fine), it just needs to be bridged to MyWLAN and to act as a simple ethernet switch for the wired connections, forwarding the DHCP IP addresses provided by Airport to the clients.

2) Is it possible for a single network to have both a 802.11G and an 802.11N router without the speed dropping to G level? (This seems unlikely, even if the G device is somehow configured to not actually provide any wireless connectivity to clients.) That is, can individual devices connect with different speeds; say, a recent Mac could connect with N, and older devices (including the bridged Buffalo) would connect with G?

All in all, this looks like a real bitch to configure, but assuming it's possible (and the DD-WRT firmware is quite capable), I'm willing to make the effort just to get rid of the damned bedroom-to-living room cable.
posted by lifeless to Computers & Internet (9 answers total)
1) If everything is already set up, it's easy. The Airport software has an easy bridge setup along the lines of "Join an existing network." I do this to use AirTunes on an Airport Express with a Linksys WRT handling DSL duties.

2) I don't know, but I think they'll have to run at the same speed. Isn't the G router between you and the world anyway?
posted by rhizome at 9:28 AM on September 1, 2007

In the new setup, it's the Airport that would be the joinee, and the old Buffalo the joiner, so it's the N router that would be between my network and the world. But if Airport Extreme can do it, I'm positive so can DD-WRT, if in somewhat less straightforward manner. Good to know, thanks.

G speed will suffice if it's the highest available option in this setup (if someone knows for sure, do tell). The three machines in the bedroom are the ones with the heaviest LAN bandwidth needs, and they've got the wired gigabit ethernet anyway.
posted by lifeless at 9:50 AM on September 1, 2007

I should have just googled this properly :-). Well, I did that now, and a good tutorial for this exact type of setup can be found here.
posted by lifeless at 10:02 AM on September 1, 2007 [1 favorite]

Doh, you already have your answer but I do this exact thing with my network at home. Good luck!
posted by iamabot at 12:17 PM on September 1, 2007

Yes, you can easily do this with DD-WRT. What you want is 'client bridging mode'.

The standard way to bridge a wireless network is with WDS; this uses all the APs as APs, and extends your range. But all traffic is repeated by every access point, so it cuts your bandwidth by 1/X, where X is the number of APs you have. It's also finicky as hell to get going.

Client bridge mode is a feature in the free firmwares, where the remote AP looks like a laptop; it's just another client. But it handles all the traffic for several machines behind it. You take no speed hit, and everything just works. It's a much better way to go.

This was very painful two years ago, and it's very easy now. You're lucky you didn't try to do this too soon. :) Just use your Airport as your AP, use your Buffalo as your client bridge, and everything should work like a charm, with no special configuration required on the Airport.

If you run a 11n network with 11g clients, it will not run at full speed, but your N clients will still benefit a great deal.
posted by Malor at 12:45 PM on September 1, 2007

Oh, and configuring this is dead simple on DD-WRT. Just go to your Wireless page and change it from AP to Client Bridge mode. You shouldn't have to do anything special on the Airport at all; the Buffalo just looks like any other client.

Don't use "Repeater" or "Repeater Bridge"... that's the complex/weird setup. You'd only want to get into that if you needed to extend your range and were willing to trade off half your bandwidth and some hair-pulling time.
posted by Malor at 12:49 PM on September 1, 2007

In case you want another description on how to set it up, there's the dd-wrt wiki tutorials. Which include bridging, client bridging and WDS.

If you put the airport between the internet and a 802.11N enabled laptop, then it'll connect at N speeds. Even when you have the buffalo connected at G speeds. (Unless you explicitly disable that.)
posted by philomathoholic at 12:49 PM on September 1, 2007

If I can piggyback on this question - how does QOS work in this type of setup? If I set QOS on the DD-WRT "joiner" router, will it prioritize any packets sent through it? Or does QOS only kick in on the router connected to the internet?
posted by Gortuk at 3:19 PM on September 1, 2007

When the DD-WRT router is connected in Client Bridge mode, with routing turned off, it doesn't do any QoS or packet inspection. It operates in a very 'dumb' mode. Basically it just passes packets. I don't think it's even on the IP's really operating just down at the Ethernet/802.11 frame layer. Frame comes in from the wired port, it goes out either one of the other wired ports, or it gets pushed out the wireless port. All the higher functions of the device are disabled, in the most basic client-bridge setup.

Really, you want to do most of your QoS-ing on the router that's actually connected to the Internet -- your "gateway" router. It might be possible to set up the DD-WRT unit that's in Client Bridge mode to do some QoS (you can set it up so that it does routing while in bridge mode, and possibly QoS too), but unless you have severe bandwidth shortages on the wireless part of the network (the basestation-to-basestation 802.11b/g part), I wouldn't enable it there.
posted by Kadin2048 at 4:22 PM on September 1, 2007

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