Date: Fri, 15 Feb 2002 08:59:49 -0800 From: "Kevin Oberman" <oberman@es.net> To: Vinod Namboodiri <geekvinod@yahoo.com> Cc: Jason Hunt <leth@primus.ca>, freebsd-net@freebsd.org, freebsd-mobile@freebsd.org Subject: Re: MAC Layer of TCP/IP stack Message-ID: <20020215165949.E92E05D09@ptavv.es.net> In-Reply-To: Your message of "Fri, 15 Feb 2002 08:20:56 PST." <20020215162056.49296.qmail@web21106.mail.yahoo.com>
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> Date: Fri, 15 Feb 2002 08:20:56 -0800 (PST) > From: Vinod Namboodiri <geekvinod@yahoo.com> > Sender: owner-freebsd-net@FreeBSD.ORG > > Not actually.Its more to run QoS experiments and need > to customize some medium access protocols like csma/ca > e.t.c.Guess i cant get to the csma protocol from the > freebsd tcp/ip stack source code. CSMA/CD is ALWAYS implemented on the card in microcode, usually in ROM and is totally untouchable from the standard API, let alone TCP or IP. The closest you can come is a total reload of the code and many cards don't support this. In the world of full-duplex Ethernet, there is no CSMA/CD and virtually no MAC. Only cards running half-duplex still use CSMA/CD. The specifics of CSMA/CD were in the original 802.3 specification and the rules have never changed since then (although they are broken). 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. 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 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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