From owner-freebsd-stable Mon Aug 27 8: 1:47 2001 Delivered-To: freebsd-stable@freebsd.org Received: from pluton.ispras.ru (pluton.ispras.ru [194.186.94.6]) by hub.freebsd.org (Postfix) with SMTP id 07E3E37B403 for ; Mon, 27 Aug 2001 08:01:38 -0700 (PDT) (envelope-from grn@ispras.ru) Received: (qmail 39051 invoked from network); 27 Aug 2001 14:58:49 -0000 Received: from unknown (HELO gate.ispras.ru) (194.67.37.200) by pluton.ispras.ru with SMTP; 27 Aug 2001 14:58:49 -0000 Received: from ispgate (ispgate [194.67.37.200]) by gate.ispras.ru (8.11.2/8.11.1) with ESMTP id f7RF1OM25040 for ; Mon, 27 Aug 2001 19:01:26 +0400 (MSK) Date: Mon, 27 Aug 2001 19:01:24 +0400 (MSK) From: Grigory Kljuchnikov To: Subject: Ethernet behaviour if dst ether addr = local ether addr Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Hello, I know my question may be out of this list scope, but perhaps anybody knows answer... I'm interested in how ethernet process a packet with ethernet dst address = local ethernet address. Does this packet appear on the wire? If not, who does loopback IP or Ethernet? And does that behaviour define in IEEE 802.3 standard? If not, which standard define the ethernet (or IP) behaviour in this case? I've looked the source code of ether_output() function (from /usr/src/sys/net/if_ethersubr.c) and found an interesting comment (lines 320-328): /* * If a simplex interface, and the packet is being sent to our * Ethernet address or a broadcast address, loopback a copy. * XXX To make a simplex device behave exactly like a duplex * device, we should copy in the case of sending to our own * ethernet address (thus letting the original actually appear * on the wire). However, we don't do that here for security * reasons and compatibility with the original behavior. */ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ In this case what is 'the original behavior'? And what about duplex device behaviour? Sorry, if I take your time! Thanks. Grigory Klyuchnikov, System Engineer, Institute for System Programming Russian Academy of Sciences To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message