RE: Wireless N

["Stephen Alford" <stephena () sbspros net>]

Thanks, Paul, for the quick reply.  

If I understand right, "pre-N" routers have added 802.11e stuff to the MAC
layer and MIMO to the PHY layer.  If so, do routers marketed as MIMO "only"
have the PHY enhancements, sans 802.11e addtions ex. Airlink MIMO
(www.airlink101.com)?  

So far I have found only one true "pre-N" router from Belkin. Do you know of
any others?  Have you found that pre-N devices used at b/g levels are still
better performers then default b/g devices?

Thanks,
Stephen 


Stephen Alford, MCT, MCSE+Security, CCNA, CCDA, ASE
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-----Original Message-----
From: Paul Cychosz [mailto:pacychosz () wisc edu] 
Sent: Monday, November 21, 2005 12:07 PM
To: Stephen Alford
Cc: security-basics () securityfocus com
Subject: Re: Wireless N

Hi,

802.11n has no security enhancements.  It is purely high-throughput
enhancements (theoretical speeds of around 600mbps in it's best mode). 
Right now you can probably buy pre-n devices but it isn't worth it. 
There are 2 main proposals, TGn Sync, and WWiSE... but now they're combining
them into a Joint Group proposal (that will be probably heavily sided
towards TGn Sync since it got 74% of the last vote... 1% more and it would
have been chosen outright) that should be finished some time very soon.
Basically, there are enhancements to the MAC and PHY layer.  The mac layer
implements some 802.11e stuff (QoS, block ACKs, etc.) and aggregates several
MSDU/MPDU (mac-layer frames) together so it can send it out all at once,
eliminating contention for the wireless channel between frames.  There are
some other things in the MAC layer, but the general idea is that it removes
overhead, allows multiple recipients, header compression, 1 ACK for many
frames, not having to wait a DIFS be tween frame transfers, etc.

The physical layer then uses MIMO (multiple antennas) to achieve higher
bandwidth.  Instead of using the traditional 20mhz per channel, they'll have
a mode that uses 40mhz of it.  I don't know what this means for japan since
there are laws against using more than 20mhz at a time (or i think it's
18mhz actually).  Additionally, the phy-layer does something called OFDM,
something that 802.11a does already.  Basically, it just splits up a radio
signal into many narrowbands and them recombines them at the source.  This
coupled with aggressive FECs tries to defeat noise in the environment.

see: www.tgnsync.org, www.wwise.org, and www.802wirelessworld.com also, just
look up the acronyms on wikipedia if you're interested.

paul


----- Original Message -----
From: Stephen Alford <stephena () sbspros net>
Date: Monday, November 21, 2005 7:20 pm
Subject: Wireless N
To: security-basics () securityfocus com

> Good day List members,
>
> I have a general query on whether the deployment of Wireless N (vs. 
> b/g) has
> any add'l security issues and/or is worth the extra expense of the 
> hardware.If anybody has experience with the new Wireless standard, 
> please could you post your feedback.
>
> Thanks in advance for your input.
>
>
> Stephen Alford, MCT, MCSE+Security, CCNA, CCDA, ASE Director, Partner 
> Practices & Solutions, SBS Pros
> Email: stephena () sbspros net