Date: Fri, 15 Feb 2002 09:29:54 -0800 From: Michael Sierchio <kudzu@tenebras.com> To: Kevin Oberman <oberman@es.net> Cc: Vinod Namboodiri <geekvinod@yahoo.com>, Jason Hunt <leth@primus.ca>, freebsd-net@freebsd.org, freebsd-mobile@freebsd.org Subject: Re: MAC Layer of TCP/IP stack Message-ID: <3C6D4592.8010809@tenebras.com> References: <20020215165949.E92E05D09@ptavv.es.net>
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Kevin Oberman wrote: > In wireless (802.11) protocols there is also no CSMA/CD as it is not > applicable to wireless although there IS a MAC and it is usually > loadable, though documentation and source is proprietary and general > hard to get. 802.11 supports CSMA/CA, where the A stands for the avoidance algorithm -- CD is impossible where the transmit and receive antennas are coincident. And I don't know why you declare CSMA/CD rules to be "broken" -- they've worked surprisingly well since Metcalfe and Boggs devised Ethernet. The major problem as I see it is that the wait period is defined by the physical layer constraints (fixed time), whereas increasing bandwidth makes the wait time a higher and higher percentage of the bandwidth. There are certainly wireless cards that permit 802.11 raw frame processing by the host -- this is a great help to those miscreants who engage in the exercise of driving around and snooping on others' 802.11 nets with the excuse that they're "helping" the rest of us. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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