Can you plug two WRT54Gs into a router?
May 13, 2007 11:22 AM   Subscribe

Is there any reason I wouldn't be able to plug two Linksys WRT54G WiFi devices into a Linksys BEFSR81 LAN router? Will the WRT54G's play nice or will they fight with one another, requiring configuration to be done? SSIDs will be different of course.
posted by rolypolyman to Computers & Internet (12 answers total) 3 users marked this as a favorite
Response by poster: I pointed this out to my wife and she thinks the WRT54G's won't fight with each other but will fight with the BEFSR81... she says this is a daisy chain of routers and she thinks it can't work. However I did hook all this up and it seems to be working fine. Is this a disaster waiting to happen?
posted by rolypolyman at 11:32 AM on May 13, 2007

Yes, you may need to reconfigure them as they may conflict. Think DHCP, IP ranges etc... The routing part should be OK (each takes an IP from the Ethernet port and dishes out IP's over the WLAN) I don't know how your routers are set up.

Also, if you're putting them next to each other WiFi interference is going to destroy your signal.
posted by puddpunk at 11:46 AM on May 13, 2007

Depending on how your network is set up, you probably need to make sure that the BEFSR81 is set to "gateway" mode (assuming it's closest to your internet connection) and both the WRT54Gs set to "router" mode. On the WRT54G this setting is in the http-based setup under Setup->Advanced Routing. Having a router set to "gateway" mode and plugged into another router set to "gateway" mode can cause problems. Also you need to make sure that only your gateway router (probably the BEFSR81) has "DHCP Server" enabled. Having multiple DHCP servers on a single network can cause problems.
posted by Vorteks at 11:48 AM on May 13, 2007

No that should be fine.

Depending on how you configure things you may have a lot of redundant address translation, and you might have to jump through some hoops to talk to a device on one WRT54G from a device on the other, but there's nothing that these guys are fighting over!

The BEFSR81 probably can't even tell that the WRT54Gs are any different from single computers.
posted by aubilenon at 11:49 AM on May 13, 2007

Oh, yeah! Wifi intereference! Use channels that are at least a three or four apart.
posted by aubilenon at 11:50 AM on May 13, 2007

The Internet is just a series of routers. Doing it in your house is just a small scale version of what all the big ISPs are doing. :) The fact that the links go five feet instead of five hundred miles doesn't matter in the least.

Unless you want truly separate wireless networks, don't use the WRTs as routers. Plug them into the BEFS on their INTERNAL network ports; that will make them into just wireless access points. They won't do any NAT or firewalling, so all your wireless clients will be able to see each other and the network. It'll turn the whole network into one entity, with two wireless channels. Run the two WRT units at least 5 channels apart. Generally, the only channels that should get used are 1,6, and 11.

You'd plug the WRTs in via their external (WAN) link if you needed to separate your wireless networks for some reason -- if you didn't want machines in one network to be able to see machines in the other net. If you configure it that way, they will do separate firewalling and NAT so that the two networks are distinct. In fact, you'd have THREE networks; the BEFS private network, into which the WRTs plugged, and then each WRT would have its own separate private net, for a total of three.

Clients behind the WRTs would get NATted to the BEFS' private range, and then the BEFS would NAT it again to the public IP it has from your provider. The double NAT could potentially cause issues with apps that want to open a public port. Using UPnP, they'd instruct the WRT to open a port, which would happen, but the WRT would not tell the BEFS to open a port, so connections will never make it in. This means apps like Bittorrent almost certainly won't work. You'd probably have to set up static IPs and open ports manually.

The BEFS units are old; if you don't need all the ports, you could just replace it with one of the WRTs, and then connect the other unit to that. Again, you'd use the external port if you want to separate the networks, and an internal port if you want to unify them. You'd have two networks instead of three, but the problems with port forwarding would still exist with the second network.

Oh, also note: I think the WRTs and the BEFS will probably all have their DHCP servers on. If you're running an all-in-one network, disable DHCP on all the units but one. If the units are in separate networks, leave the servers on.

Yet another note: if you unify them, make sure to put them all into the same class C network; I think Linksys uses 192.168.1.X by default. When you pick your firewall device, look to see what it likes to use as the internal network, and adjust the others to suit.

If you're running as separate networks, you might want to explicitly change all of the private networks to be different address ranges. This will avoid some potential bugs. If the BEFS unit is NATting to 192.168.1.X, and then the WRT units are NATting from that range to the SAME range internally, you could end up with some very strange results. I have no idea what would happen, but I think it would be bad. In that scenario, make sure the WRT private ranges are different from the BEFS private range. (if the BEFS uses 192.168.1, use 192.168.2.)

Overall, a unified network is probably easier to understand.... mostly all you have to do is shut off two DHCP servers, make sure all three units have addresses in the same class C, and everything just works. If you separate the networks, you turn into a tiny ISP and need to have a better idea of what you're doing... you'll probably have to set up static IPs and port forwarding if you want to run apps like bittorrent.
posted by Malor at 12:35 PM on May 13, 2007 [1 favorite]

Oh, also: don't use WEP. WEP is completely insecure. Use at least WPA. WPA2 is much better.
posted by Malor at 12:36 PM on May 13, 2007

Malor said everything I would have.
posted by rbs at 2:26 PM on May 13, 2007

It's my understanding that doing this will cause a rip in the space time continuum. You will be transformed into a goat.

If you survive the transformation and follow the advice given here, you will end up with two (three?) different subnets. If this is a problem, you'll need to "bridge" the 54G routers. Unfortunately, you can't bridge Linksys wireless routers using Linksys firmware. They don't support it.

See this. Also, no warranties express or implied, etc. and of course, if this is beyond your technical desire/capability, just go right ahead and configure the network as you already have.

Alternative 2: get rid of the 54g's and use access points instead.
posted by disclaimer at 2:27 PM on May 13, 2007

If you do want to go to APs instead of routers, don't throw away the WRT54Gs, load a third party firmware on them, although it's harder with the latest models, it can still be done.
posted by wierdo at 8:14 PM on May 13, 2007

You don't need to do any of that. Just use the standard LInksys firmware, and plug an INTERNAL port from each into the BEFS. Voila, network bridged onto the wireless, no extra effort. Change their internal IP addresses to the same range as the BEFS, turn off their DHCP servers, and it's a done deal.

I've done this myself with the Linksys standard firmware, so I KNOW it works. I only did one, but there's no reason why it won't work with two.
posted by Malor at 12:45 AM on May 14, 2007

Always, always one more thought. There's a difference between wireless bridging and being an access point. Being an access point is the default mode. You connect a physical wire to the AP, and then wireless clients can join your network via that signal. It's like they're connected via a wire; the access point takes care of forwarding the correct packets. This is a separate function from the routing and firewalling that these units can do onto the WAN port. It's common to do all these at once, but not required. If you want just an AP, where all it does is let wireless clients onto your network while some other unit does your firewalling and NAT, it's very easy.

Wireless bridging is different, and actually refers to two different things. The first, and most common, is a signal repeat set up between two or more APs to extend range. Any traffic that any AP sees is repeated so that all the APs get it. This allows you to extend range quite a bit, but it cuts your speed down by half if you have two APs, or to 1/3rd if you have 3. (This is called WDS, or Wireless Distribution System.)

Less commonly, you may want to use an access point, not as a server, but as a client. You use the AP to connect to another one, but it looks like a standard client... like a laptop. It bridges one or more devices behind itself. To the access point on the main network, it's just a client with more than one IP address. This method of bridging doesn't have the speed hit that WDS does, but it also won't extend wireless range; the secondary AP is just a client, and can't offer wireless services to anyone. All it does is bridge its physical network onto the wireless. It's kind of like an access point in reverse. This is usually called "client-mode bridging".

Linksys default firmware can't do those advanced functions. It can only be an access point. If you want WDS or client-mode bridging, you'll have to use one of the open firmwares.

But basic AP mode is all this poster wants. He wants two of them, for whatever reason, but it's really the same thing as one. The standard Linksys firmware should do what he wants very nicely.
posted by Malor at 1:15 AM on May 14, 2007

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