*headdesk*

IMO...never set your APs to Auto. Spend the time, or the money, or both, for a 
decent site survey. Use only channels 1, 6, & 11, and lay your APs out so that 
the APs on the same channels are not close to each other, because too much 
signal overlap on the same channel will cause RF collision.

Once setup, review periodically (quarterly, semi-annually, annually, etc) to 
make sure no one has added any wireless in the area that would interfere (or 
use the utilities built in if you have something like Cisco Wireless Control 
System with centralized controllers). Keep in mind that RF noise is additive. 
Any NON 802.11 RF signal will be considered noise, and the more there is, the 
more it will work against your 802.11 equipment - decreasing the 
signal-to-noise ratio (SNR) and increasing the chances of wireless data traffic 
corruption.

Side note: There are enough channels in the 802.11a spectrum (5GHz) that 
channel plans are not usually necessary.

Furthermore.....Anyone dealing with wireless networks need to understand SNR 
(Signal to Noise Ratio) and how it impacts wireless performance. It's like 
trying to talk with another adult in the same room when you have a couple of 
chatty children in the same room. You can carry on a conversation with another 
adult across the room, but if you double the number of children, you have to 
raise your voice. Add enough children, and no matter how loudly you shout, the 
other adult will never hear you, and vice versa...

Here's a link that does a good job of explaining it and provides some 
guidelines:

wi-fiplanet.com - How to: Define Minimum SNR Values for Signal 
Coverage<http://www.wi-fiplanet.com/tutorials/article.php/3743986/How-to-Define-Minimum-SNR-Values-for-Signal-Coverage.htm>

Hope this helps.

Jonathan L. Raper, A+, MCSA, MCSE
Technology Coordinator
Eagle Physicians & Associates, PA
[email protected]<BLOCKED::mailto:%[email protected]>
www.eaglemds.com<BLOCKED::http://www.eaglemds.com/>

________________________________
From: John Hornbuckle [mailto:[email protected]]
Sent: Tuesday, October 19, 2010 8:50 AM
To: NT System Admin Issues
Subject: Update: Group Policy Problems Over Wireless

No firm resolution on this yet, but possibly a bit of progress.

I kept thinking about the problems we were having in this lab. The computers 
are the same computers we had in the lab last year, and last year we didn't 
have these problems. So, what changed? Two things: we replaced the WAPs that 
serve the lab with newer models, and more WAPs were installed in that area of 
the building.

So I got to thinking that maybe the issue was an incompatibility between 
Broadcom NICs and the new WAPs, or an issue caused by too many WAPs being in 
the same vicinity. But we have another lab in a different area of the building 
that has the exact same WAPs and the exact same computers-but no problems. So 
that left the latter possibility-lots of WAPs stepping on one another's toes-as 
the prime culprit.

The WAPs are Cisco/Linksys, and they all default to the same channel. I changed 
the ones in the area that was having the problem to "auto," but that didn't 
seem to really help. So next I forced the WAPs that serve the lab to "g" rather 
than "b/g/n." As moment, everything is working fine. My tech and I will be 
watching throughout the week, and if things are still working after a few days 
we'll consider the issue resolved.


John


From: John Hornbuckle [mailto:[email protected]]
Subject: Group Policy Problems Over Wireless

Short version:
Is there a trick to improving group policy processing when accessing the 
network wirelessly?


Long version:
We have a lab with machines that have Broadcom wireless NICs in them. Vista OS, 
connecting to Server 2008 R2 DC.

I'm trying to deploy a piece of software to these machines via Group Policy. I 
have things setup so that if the machine is a member of a certain group, the 
software is deployed. Unfortunately, it only worked correctly on one of the 
machines-on all the rest, the software isn't being deployed.

So I connect to any of the machines that didn't get the software, and run 
gpresult. It doesn't show me that those machines are members of the group that 
gets the software. But I know they are; I've confirmed in ADUC on the DC. 
They're just not picking up group membership.

Looking at the event log for events that happen around startup, I see things 
that make me think group policy processing is trying to happen prior to the 
wireless network being initialized. Things like:

Event ID 5719 (There are currently no logon servers available to service the 
logon request.)
Event ID 129 (NtpClient was unable to set a domain peer to use as a time source 
because of discovery error.)
Event ID 1129 (The processing of Group Policy failed because of lack of network 
connectivity to a domain controller.)

Connectivity to the DC is fine once you get the [Ctrl] + [Alt] + [Del] window. 
You can log in (including as someone who has never logged into the machine 
before), ping the DC, browse to \\domain\syvol<file:///\\domain\syvol>, and so 
on. It's just that at that point, group policy processing seems to have given 
up. My machines aren't figuring out that they've been added to a new group.

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