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Extending the coverage of the existing wireless network

Tags:
  • Configuration
  • Wireless Router
  • Wireless Network
  • Wireless Networking
Last response: in Wireless Networking
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March 10, 2010 7:13:22 AM

Hello, i've got a network with a wireless router using Edimax BR-6204WLg and its working but I'm planning to extend its coverage by putting up 4 to 6 additonal wireless router with the same brand to the existing network is this possible? thanks for the help

More about : extending coverage existing wireless network

March 10, 2010 10:43:24 AM

Yes, it says from the specs that Edimax BR-6204WLg supports wireless mode:
AP/AP Client / Bridge/Bridge+WDS, but I don't know how to go about it initially. Could you please give me some instructions to configure it. Many thanks in advance and I appreciate your quick response.
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March 10, 2010 1:24:12 PM

Your router actually supports WDS and universal wireless bridging, and either would do the job.

WDS is not a wifi certified protocol, so implementations vary across manufacturers. But as long as you stay w/ the same make & model, you shouldn’t have a problem. Another gotcha w/ WDS is sometimes it has “hidden” limitations. For example, some will only supports WEP. And there is usually a limited number of other APs to which any one AP can be bridged (most I’ve ever seen is four). Since I’m not familiar w/ Edimax’s WDS implementation, I can’t say whether such limitations exist/apply. But it’s something to watch out for because the literature often doesn’t mention it (at least it’s not obvious, if it’s there at all, it’s often buried in the fine print).

The WDS concept is pretty simple. Somewhere in the router configuration you’ll enable WDS then specify the MAC address of each of the other APs you want associated w/ the current AP. You can create all kinds of complex relationships; all APs only communicating w/ the primary router, some APs only communicating w/ other APs, or all of them communicating w/ each other. It just depends on the type of problem you’re trying to solve. You can also prevent wireless clients from accessing any given AP so that it only serves wired clients, not wireless.

So let’s assume you want to have your primary router’s wireless reach extended by distributing four (4) other identical routers. Each of those four routers will ONLY communicate w/ the primary router, NOT each other (aka star topology). And each will allow both wired and wireless clients.

You configure the primary router as usual except also enable WDS, specify the wireless mode as AP+WDS, and then add the MAC address of every other router to the primary router’s list of WDS associations. Similarly, you configure each of the remote routers as AP+WDS mode and add the MAC address of the primary router to their list of WDS associations. All must use the same wireless security settings (SSID, channel, encryption type, etc.). And since these are routers, you need to disable their respective DHCP servers to prevent conflicts w/ the DHCP server of the primary router.

By default, all the remote routers will use DHCP to configure themselves w/ the DHCP server of the primary router. That’s fine, although from a management perspective, I prefer to use a static IP assignment. Or alternatively, if your primary router supports DHCP reservations (i.e., you can assign a fixed IP address to specific MAC addresses), use it. Either way, just like your router, it’s a lot easier to manage these devices if their respective IPs are constant and predictable. I also recommend a simple convention. Assuming the primary router is 192.168.1.1, assign each remote router successive numbers based on increasing distance from the primary router; 192.168.1.2, 192.168.1.3, etc. Again, it just makes things easier but strictly speaking isn’t necessary.

That’s about it. Once configured properly, it basically just works.

You can create other network topologies besides the star topology discussed here. You might have a particularly remote location and need to wirelessly bridge using TWO routers (primary router->router #2->router #3). Arrange them as you see fit.

But beware. Because only two wireless stations on the same freq. can be communicating at the same time, each additional wireless “hop” will cut your bandwidth in HALF! That’s because every other AP must wait until other transmissions complete before they can use that same freq. In effect, wireless access is serialize or queued. So there’s only so far you can go w/ wireless bridging before it starts to break down, it only scales so far. How many APs you can employ as a practical matter is hard to say since it would depend on demand and usage patterns at your location. But it’s something to be aware of. I just don’t want ppl to be caught flatfooted after they get all this working then wonder why things have gotten a bit slower lately since all these wonderful changes.

As I mentioned at the beginning, your router also supports UNIVERSAL wireless bridging. What makes it different from WDS is that it will work w/ ANY wireless router or AP. It doesn’t use WDS. It establishes a wireless connection in exactly the same way as any USB/PCI wireless adapter you might find on your typical desktop/laptop.

This has several advantages. As I said, you can connect it to ANY wireless access point. And it doesn’t suffer from the potential limitations I described earlier w/ WDS (e.g., WEP only). You have access to all the same capabilities as any other wireless client (WPA2, WPA, AP isolation, whatever). And you don’t have to mess w/ identifying MAC addresses between APs. And you can associate as many APs to other APs as you like. You can even use different wireless security configurations (not sure that I would recommend it, but it is possible). About the only thing it shares in common w/ WDS is the performance hit I spoke of earlier. That is a limitation of wireless itself, so it affects ANY form of wireless bridging.

The obvious question everyone always asks is, then why would anyone ever use WDS?

The answer is, most ppl DON’T. A universal wireless bridge is so much less hassle, so much less restrictive. WDS was the first wireless bridging technology available and became a de facto (if not wifi certified) standard. Since then universal wireless bridging has pretty much replaced it. WDS is still around and often touted by the manufacturers, but it’s just a PITA to work w/ compared to a universal solution.

So take your pick. Personally I would recommend universal wireless bridging (specifically wireless repeater bridging) and see if it works for you. If it doesn’t, WDS won’t be any better or easier anyway. You still have to do all the other things; assign each a unique IP address, disable their DHCP servers, etc. It’s just how they are associated that changes.
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