Netgear WNR3500L & WNR834Bv2 wireless channel assignments - something odd?!?

[DaveVM]

Folks,

I've been playing around with the channel assignments on my routers and found something odd, very odd. With two Netgear Routers (WNR3500L & WNR834Bv2) and wireless channel assignments. All have factory firmware installed.

I thought I had set the channel to 6 on the 834b's (have two in repeating mode, one base, other repeater). Figured I would verify it with my laptop which is running Linux. Downloaded WiFi Radar for it (can't use inSSIDer, no Linux version) and was stunned to find it said the 834b's were on channel 8 - not 6 like I set them.

Odd I thought, so I fire up the 3500L, connected to another Linux box (building a NAS from the info found here at SNB) Booted a Linux CD, and accessed the 3500L and went through the wireless channels 1-11 and checked the laptop WiFi Radar for the channels. Here is the result.

Netgear WNR3500L Channel assignments.

3500L WiFi Radar
1 - 3
2 - 4
3 - 5
4 - 6
5 - 7
6 - 8
7 - 5
8 - 6
9 - 7
10 - 8
11 - 9

What is up with this!

Netgear apparently at least by WiFi Radar has moved their channels either up or down by 2, and the channels 1,2,10,11 are missing!

My neighborhood has a lot of wireless and WiFi Radar shows all the details.

So my question then is did indeed Netgear do this? Which I would find hard to believe. And does this explain some of the problems with trying to get Netgear to talk with other routers? (I've been trying to get some enGenius 9850's to cooperate)

I would be very interested to know what others find out by going through the channels with other or the same Netgear routers and what inSSIDer or other WiFi detection software/hardware reports the channel to be.

Now either I'm missing something really easy or...

Thanks

Dave

 

[thiggins]

If you have the routers set to 40 MHz bandwidth mode (NETGEAR may call this "up to 300 Mbps" mode), then there are two channels in use. This could be causing the misidentification.

The other thing is that some routers aren't clear about the actual channels in use when 40 MHz mode is used. For example, the WNDR3700 shows just the primary channel in the wireless settings when set to "up to 300 Mbps" mode. You need to look at the Router Status page to see the Primary channel (in my case 11) and the secondary channel (7).

 

[DaveVM]

Tim,

Appreciate the response. You hit the ball out of the park! As I do have them set on 300Mbps mode as Netgear calls it.

OK. That makes some sense in my head but not much. Because I thought there were some standards (FCC or otherwise) that were/are to be met. But apparently there is some leeway. (military background here and used to things being very specific) Reminds me of "Measure it with a micrometer, mark it with a magic marker, cut it with an axe!"

Now the question is where can I find more info on this? Obviously here at SNB and yes I will search for it but if there is some other place to find it. Please let me know.

Thanks again.

 

[thiggins]

What sort of information are you looking for?

802.11b and g use 20 MHz wide channels.

802.11n in the 2.4 GHz band is supposed to default to use 20 MHz wide channels due to the limited spectrum that provides only three "non-overlapping" channels, 1, 6 and 11.

When you use 40 MHz mode you eat up two out of three free channels. If you park your primary channel on 6, you essentially take up the whole 2.4 GHz band.

The spectral plots in this article show this.

My tests have shown that using 40MHz mode provides higher speed only under strong to medium signal conditions. Once signal levels drop to low levels, there is no throughput gain and adapters actually have a harder time connecting and/or maintaining a connection.

 

[DaveVM]

Tim,

The info you provided is some of what I was looking for, yet I think the manufacturers should provide this as well. Granted not in printed form, 99% of people wouldn't read it. But it could/should be on their websites or included as a file on the distribution CD included with the routers.

The more I dig into this archaic world of wireless mayhem the more I find (as I know you have) how terminology is so loosely bandied about. Because as you have done for us, you have been able to get it down to comparing apples to apples, and broke through the techno speak that the manufacturers use.

So anyway I went to 130mbps to get the narrower frequency. Now to see if there is any improvement throughout the house. Suspect there will.

Thanks Again