From owner-freebsd-hackers Thu Oct 8 00:22:58 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id AAA11341 for freebsd-hackers-outgoing; Thu, 8 Oct 1998 00:22:58 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from verdi.nethelp.no (verdi.nethelp.no [158.36.41.162]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id AAA11322 for ; Thu, 8 Oct 1998 00:22:44 -0700 (PDT) (envelope-from sthaug@nethelp.no) From: sthaug@nethelp.no Received: (qmail 29260 invoked by uid 1001); 8 Oct 1998 07:22:36 +0000 (GMT) To: archie@whistle.com Cc: mike@smith.net.au, andre.albsmeier@mchp.siemens.de, hackers@FreeBSD.ORG Subject: Re: How to send data between two network cards directly? In-Reply-To: Your message of "Wed, 7 Oct 1998 17:01:28 -0700 (PDT)" References: <199810080001.RAA23283@bubba.whistle.com> X-Mailer: Mew version 1.05+ on Emacs 19.34.2 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Date: Thu, 08 Oct 1998 09:22:36 +0200 Message-ID: <29258.907831356@verdi.nethelp.no> Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > > You can't do this. Ethernet implicitly involves several protocols, > > each with their own overheads and error correction. > > Not true.. Ethernet is just synchronous HDLC with a 32 bit checksum. > You can send and receive raw Ethernet frames using bpf(4). This may be splitting hairs, but: 10 Mbps Ethernet is *not* like synchronous HDLC, because it has a "start bit" (the preamble). 100 Mbps Ethernet is different - this is more like a synchronous serial line in that there's signal on the cable at all times. Also, half duplex Ethernet uses CSMA/CD, which is definitely what I would call a protocol (implemented in hardware). Steinar Haug, Nethelp consulting, sthaug@nethelp.no To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message