Date: Tue, 10 Jul 2001 07:41:22 -0700 From: "Kevin Oberman" <oberman@es.net> To: Greg Troxel <gdt@fnord.ir.bbn.com> Cc: mobile@FreeBSD.ORG Subject: Re: Wireless base stations Message-ID: <200107101441.f6AEfMA19031@ptavv.es.net> In-Reply-To: Your message of "10 Jul 2001 08:30:25 EDT." <rmipub955lq.fsf@fnord.ir.bbn.com>
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Greg, Setting up a large facility for 802.11b can be a very complex task. It's not as simple as to "set them to different channels". First, channels overlap and you can use no more than three different channels of those available in the US in a network where there is to be hand-offs. Beyond that, the radiation pattern is omni-directional. That means that they MAY radiate up and down to adjacent floors. But, if there is enough metal in the floors (and there often is), there may not be. But you really need to check. Even on a single floor, beams and ducts can cast shadows that create dead zones. It can be frustrating. For hand-offs to work, you need all of the access points in a single collision domain. That may be difficult to do in a large building. This is not meant as a tutorial on large wireless network installation. It's more of a warning that you need to carefully read the documentation and then talk to someone knowledgeable in the area. (The documentation with low-end products is often weak.) R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman@es.net Phone: +1 510 486-8634 > From: Greg Troxel <gdt@fnord.ir.bbn.com> > Date: 10 Jul 2001 08:30:25 -0400 > Sender: owner-freebsd-mobile@FreeBSD.ORG > > Can people comment if these cheap APs are running in true > 'infrastructure mode' and can support multiple APs on an ethernet with > roaming across APs similar to the Lucent AP500? > Specifically, if I bought 14 of the cheapest Linksys bridges and put 2 > to a floor on my 7-story building all on an Ethernet run around to all > 14 of them, and set them to different channels, would I then be able > to wander around floor to floor and stay on the net with the same IP > address? > > One person commented 'no filtering by MAC'. Does this mean that every > packet on the wired Ethernet will end up over the air, even if it is > unicast and the corresponding address is not associated with the AP? > Does this differ between the cheap APs and the Lucent products > (AP-500/1000, ignoring the RG)? > > I realize I'm asking different questions; I'm considering what it > takes to set up my building at work rather than a single AP for home > (I have a Lucent card in a pcmcia bridge in 'create IBSS' mode there). > > Greg Troxel <gdt@ir.bbn.com> > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-mobile" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-mobile" in the body of the message
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