From owner-freebsd-hackers@FreeBSD.ORG Sun Apr 3 05:22:45 2005 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 940F616A4F9 for ; Sun, 3 Apr 2005 05:22:45 +0000 (GMT) Received: from ebb.errno.com (ebb.errno.com [66.127.85.87]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4D82243D45 for ; Sun, 3 Apr 2005 05:22:45 +0000 (GMT) (envelope-from sam@errno.com) Received: from [66.127.85.92] ([66.127.85.92]) (authenticated bits=0) by ebb.errno.com (8.12.9/8.12.6) with ESMTP id j335Mdms018425 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sat, 2 Apr 2005 21:22:39 -0800 (PST) (envelope-from sam@errno.com) Message-ID: <424F7DDE.80806@errno.com> Date: Sat, 02 Apr 2005 21:23:42 -0800 From: Sam Leffler Organization: Errno Consulting User-Agent: Mozilla Thunderbird 1.0 (Macintosh/20041206) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Joerg Sonnenberger References: <20050402065052.GT44514@numachi.com> <20050402162842.GU44514@numachi.com> <20050402171635.GV44514@numachi.com> <20050402172355.GA1069@britannica.bec.de> <424F172E.9070201@errno.com> In-Reply-To: <424F172E.9070201@errno.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit cc: freebsd-hackers@freebsd.org Subject: Re: which Wifi cards can be used for a WAP? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 03 Apr 2005 05:22:45 -0000 Sam Leffler wrote: > Joerg Sonnenberger wrote: > >> On Sat, Apr 02, 2005 at 12:16:35PM -0500, Brian Reichert wrote: >> >>> In perusing many of these cards specs, I see many of them offer a >>> 'turbo mode' of 108 Mbps. >> >> >> >> That's a vendor-specific mode. I strongly advice you _against_ using it, >> it's using at least one additional channel and only adds speed for very >> short distances. If you follow the common recommendation of leaving one >> channel before and after the active channel, you end up using at least >> 5 channels for turbo mode compared to three for normal, it's not worth >> the trouble. > > > This is misleading. First turbo mode can only be used in the 2.4G band > on channel 6 and does not impact operation on channels 1 and 11. Any > channels in between already suffer from normal (i.e. non-turbo) use > because the channel spread in the 2.4 band means traffic is visible if > you use the in-between channels. Further, turbo mode (as part of > SuperG) requires that the AP detect non-turbo capable stations and > disable turbo use when such stations are present. I was wrong; turbo mode requires a 40Mhz wide band so when operating on channel 6 it'll splatter 1 and 11. Regardless, compliant AP's are supposed to monitor the air and drop out of turbo if non-turbo traffic is detected. This is part of the Dynamic Turbo component of SuperG and happens transparently to SuperG stations. Sam