Ask the Wi-Fi Guru, Episode XIX

By Aaron Weiss

September 22, 2009

Our monthly Q&A series offers advice to those seeking help with home or small business WLANs. This month our Guru offers advice on range extension and bridging, WPA-Enterprise, and static DHCP addresses, among other things.

Our monthly Q&A series offers advice to those seeking help with home or small business WLANs. This month our Guru offers advice on the common problems of range extension and bridging, among other things.


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It is that time of year again—when the children head back to school, a bit of color starts to peek through the leaves, and of course, let us not forget the meeting of the IEEE-SA Standards Board Standards Review Committee, also known as RevCom. This year’s RevCom was an exciting one, too, as they finally ratified the 802.11n wireless standard.

802.11n, which offers many important enhancements over 802.11g, including double-width channels for up to 300Mbps, has been slowly evolving for seven years. Having been assured that the ratified standard would be fully backwards-compatible, many wireless vendors released 802.11n-draft 2.0 products over the last two years. While n-draft consumer products work perfectly well for basic wireless networking in most scenarios, only relatively advanced users can take advantage of the full capabilities of 802.11n. Getting the most out of the current crop of 802.11n-draft gear can require particular configurations and a lot of time tweaking and debugging. Hopefully ratification of the standard will accelerate vendor improvements so that 802.11n gear is easier for everyone to enjoy to its fullest extent.

Q: I have a Buffalo WHR-G125 running as a primary router and I want to extend the range using a Buffalo WCR-G54. The WCR has a ROUTER/BRIDGE/AUTO mode switch on it. I was planning to use the WHR-G125 as the primary router with DD-WRT installed and the WCR-G54 as secondary. – Andy


A:  The WCR-G54 router is pitched by Buffalo Technology as having many automatic configuration features. One such feature—and an unusual one at that—is this hardware switch that can be set to “router,” “bridge,” or “auto” mode.

The “bridge” mode in this case configures the router to behave as a simple AP (access point) meaning that it disables its DHCP server and firewall, among other things. You can use this feature to create a wired bridge to extend your wireless range—in other words, by running an Ethernet cable from a LAN port on your primary router to a LAN port on the secondary router.

You would not need DD-WRT installed on your primary router (unless you wanted it for some other reason)—all the features you need to create a wired bridge using this setup are already included. In fact, anyone can create a simple wired bridge like this to extend the wireless range of his or her primary router—you don’t need a router with a marked “bridge” mode. Simply connect via cable as described and configure your secondary router to disable the WAN connection, disable DHCP server, and disable the firewall. Manually configure the secondary router’s LAN IP address to an address compatible with your primary router (for example, if your primary router is 192.168.1.1, configure your secondary router to 192.168.1.2).

Of course, the key word in setting up a wired bridge is “wired.” That is to say, you need wire, and if your routers are very far apart, that might not be very convenient.

If you wanted to setup a wireless bridge—with no cable between the routers—the scenario changes. There are two options:

1 — Using software built in to both of these routers, configure them for WDS (wireless distribution system). A WDS link between the two routers will make the secondary router behave as a kind of repeater.

2 — If WDS mode is not supported or does not work, you can create a “real” repeater setup. This would require using DD-WRT. In fact, your DD-WRT router (the WHR-125 in this case) would need to become the secondary router, and the WCR (or any router) would be the primary router. The secondary router with DD-WRT would be doing all the “work,” receiving the signal from the primary router and re-broadcasting it.

Q: We implemented WPA-Enterprise to connect all of our wireless laptops to the corporate network. Everything is working great. Now they come in with a wireless camera from Linksys (WVC200) and when we try to configure this, the only options for wireless are WEP or WPA personal. Is there any way to get this WPA personal device to connect to a WPA-Enterprise protected AP? – Dennis


A: Few home users may be familiar with WPA-Enterprise—the corporate variation on WPA security. In an Enterprise configuration, passkey authentication is not performed by the router, but is handed off to an external machine running a RADIUS server. In a situation like Dennis’s, this is done so that the authentication is tied into the organization’s Windows domain controller.

Some wireless clients do not support WPA-Enterprise mode, the Linksys WVC200 IP camera being one such example. Not to be flippant, but the easiest solution is probably to buy a new camera—one with WPA-Enterprise support.

But if we want to get all MacGyver about it, one idea does spring to mind. A router running DD-WRT or Tomato could be configured as a wireless bridge to the company’s network. In this setup, the bridge router would authenticate via WPA-Enterprise. Any devices wired to the bridge router—say, this camera—should then be online. Of course, if you don’t already have a router lying around that supports DD-WRT or Tomato, buying one simply to bootstrap this old camera may be seen as a stretch over in Accounting.

Q: The Linksys router that I have allows me to enter the MAC address of clients into a table to reserve permanent IP addresses. Is this the same as “Static DHCP” because the router will always assign the same IP Address to each client? — Koshik

A: Yes, this is exactly the same as a “static DHCP address.” It is the very definition of a static DHCP  address. Simply a case of vendors sometimes using their own lingo.

Q: I have an iPod touch and use it to listen to XM Radio around our property. The signal from our Actiontec Wi-Fi router reaches 250' or so. Will a repeater in the house increase my signal distance significantly or is there another solution? - Doug

A:  If the repeater can be placed in a location where it is significantly closer to the property than your primary router, then this may very well increase the range you can stream XM over the Internet.

Handheld devices like the iPod touch and iPhone have relatively small internal antennas and lack the wireless sensitivity you would find on, say, a good laptop. This bodes well for using a repeater to boost the signal strength, since you would essentially be leveraging the repeater’s reception to your primary router.

As described in the first question above, you could try either a WDS configuration or a “true” repeater, but the latter does require a router that can support DD-WRT.

Q: I was using my iPhone with firmware 2.2, but couldn’t connect to any wireless networks; it didn’t detect networks in range. Now I have upgraded to firmware 3.0, but the problem is not fixed yet. What can I do? - Yasser


A: There are quite a few anecdotal reports of iPhone weirdness with Wi-Fi networks. Some problems appear to be software related; others could be due to overheating or other hardware problems. In this case, it sounds like your iPhone has not detected wireless networks with either the old or newer firmware. Sounds like good reason to contact Apple—it’s probably broken.

Aaron Weiss is a freelance writer, author, and Wi-Fi enthusiast based in upstate New York. To submit your questions to the Wi-Fi Guru, simply click on his byline (above) and put "Wi-Fi Guru" in the subject line. Click here to read last month's column. For more by Aaron Weiss, read "DD-WRT Tutorial 3: Building a Wireless Bridge." For definitions of unfamiliar term, visit our searchable glossary. 

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