Discussion on:

Fix hardware and configuration issues common to wireless LANs

Many vendors are providing additional proprietary security features. These also have to be considered when troubleshooting. One such feature is to deny clients unless they have the proper WLAN name in their configuration. Another feature is an allowed list of administration console(s) by IP address. Another is to restrict administration to the wired interface only (should be the only way or at least the out-of-box default). Sometimes a "factory reset" or reboot of the access point is required. You then reconfigure it from scratch. You have recorded your configurations from initial setup, right? If the admin tool from the vendor gives you a configuration backup option, use it. That sure comes in handy for a rebooted or replacement access point. Another point about security: if you have not changed the SNMP community name (called a password by some vendors) from the common default of "public", then possibly the configuration was changed by an unauthorized person.

Had a recent (this morning actually) event that was odd. One of our Cisco 340 bridges went "dead" sometime over the weekend. Upon looking at the bridge one LED was red (BAD) and another was amber (CAUTION). I rebooted (power cycled) the bridge and right away the LEDs would come on to the mysterious state. I hooked in my laptop to the console cable to take a look for any error messages and there was nothing! Power cycle again...nothing. I figured at this point I had a dead bridge; got a working spare, hooked it up - SAME THING!!! The only common piece was the AC/DC power supply - I swapped that out on a hunch and the original bridge came back to life just fine.

Lessson here...don't always assume the hardware piece itself is at fault - it can be somethign as simple as a power supply. Funny how the power supply worked good enough to illuminate the LEDs...go figure.

I just bought a SMC 802.11a access point an nic. I can get it to work fine with no WEP, but the moment I try & use it, I can't connect. What's interesting is the NIC properties have WEP key settings & SSID settings that need to be configured, & thenthe Wireless network connection box also has a place for it. The NIC offers 128 & 152 bit encryption, but the wireless properties in XP only offer something like 40 & 60 bit. I don't get which one needs to be configured, and therefore, can't get WEP to work!

It sounds like you are probably using XPs driver for the NIC. I would check for an updated driver from SMC. If not, they probably have instructions on getting WEP configured under XP.

No wonder there are so many wide open APs out there. Obstacleslike this keep even the security conscious from locking down wireless. Most fo the blame has incorrectly been placed on administrators IMHO.

You seem to be implying that the user isn't always at fault....you obviously aren't a hardware or software manufacturer!

Its interesting that you posted this. Several years back (and a much earlier generation of hardware) we were getting reports of a server going down on the 2nd shift. As I was working late one night I observed the janitorial folks come in to the office to sweep -- and unplug the transformer pack to get clear access to the receptacle. Since then I always add a power cord clamp that screws in with the receptacle face plate screw.

I had a problem network with multiple access points and had people complaining of unexplained loss of connection in a random manner. After exploring everything, upgrading the firmware adding another accesspoint I relocated one of the original locations. Problem fixed. So what was the cause? The network jack that the access point was connected to was defective. If this had been a wired network I would have found the problem in minutes.
Mark T

Heat is an enemy to network equipment, including wireless AP. High temperatures could cause the components within wireless AP to start to fail, resulting in intermitent disconnections. It did not help that 3 wireless AP were overlapped in the same area. It was very difficult for me to track down this problem until I got hold of a tool (NetStumbler) to monitor the wireless AP signals.

Sometimes there are also problems in connecting due to Encryption settings in the wireless cards and AP.It should be checked for same Keys and also sometimes there is Inter Vendor Non compatibility issue.

I've lost my wlan connection unexpectedly many times. The only way to get it back is by gooing back to host access point and turning WEP off and back on again. Does anyone know what this resets or how this enables a connection to be established again?

I've seen that too, specifically with Linksys units. I had to actually re-enter the WEP key to get the connection back. I wondered about interference factors like those mentioned in the article but why would a wireless phone or a microwave blow out the WEP key?

The other thing we learned the hard way that you don't see people mention (and it wasn't mentioned in the article) is that some wireless manufacturers seem to interpret hex differently!?!? When you work on a wireless network with different manufacturers you should always choose to enter the WEP key in HEX! We spent hours figuring that one out.

Good article.

Mark Beans
www.QualityMark.biz

If you go to your Device Manager (Start>Settings>Ctrl Panel>Systems>Hardware Tab)and expand your network adapters. Right-click on the one you are using and go to Properties. Go to the tab marked "Power Management". Usually by default, there is a check in the option that allows the computer to turn off the device to save power. Uncheck it. If you are using a USB device, that also has the same power saving option. It is also defeated the same way. I found there are many factors that will cause your problem, but this fix is a good start. Good luck.

Anyone experienced this? We've been trying to use Windows to manage a wireless connection which we'd hoped would be machine-wide (i.e user boots up laptop they've poss never used before, logs onto network wirelessly without choosing a wireless profile or anything of the kind). Found that it only works if you first logon locally (say as administrator) and explicitly connect to the relevant wireless network. Then all will be fine (next user can logon to network wirelessly), but only until the machine is rebooted - at which point the same cycle applies. Actually that's not quite true - it will work if the user has previously logged onto that laptop and not had their profile removed. Spoke to Intel and they reckon the solution is to have a profile for each user on each laptop!
We've had to use Intel ProSet software to manage this instead (it has a "connect to available wireless network if no matching profile found" setting) but it limits our ability to upgrade from 11b to 11g as we'd need the correct Intel Centrino-compatible cards.
Maybe in XP SP2...? Or then again maybe I'm being stupid...