From owner-freebsd-net@FreeBSD.ORG Wed Jan 1 08:57:39 2014 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id A075C880 for ; Wed, 1 Jan 2014 08:57:39 +0000 (UTC) Received: from vps.rulingia.com (vps.rulingia.com [103.243.244.15]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 3AC661562 for ; Wed, 1 Jan 2014 08:57:38 +0000 (UTC) Received: from server.rulingia.com (c220-239-250-249.belrs5.nsw.optusnet.com.au [220.239.250.249]) by vps.rulingia.com (8.14.7/8.14.7) with ESMTP id s018vRwm022562 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 1 Jan 2014 19:57:27 +1100 (EST) (envelope-from peter@rulingia.com) X-Bogosity: Ham, spamicity=0.000000 Received: from server.rulingia.com (localhost.rulingia.com [127.0.0.1]) by server.rulingia.com (8.14.7/8.14.7) with ESMTP id s018vLsV034486 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Wed, 1 Jan 2014 19:57:21 +1100 (EST) (envelope-from peter@server.rulingia.com) Received: (from peter@localhost) by server.rulingia.com (8.14.7/8.14.7/Submit) id s018vLW3034485 for freebsd-net@freebsd.org; Wed, 1 Jan 2014 19:57:21 +1100 (EST) (envelope-from peter) Date: Wed, 1 Jan 2014 19:57:21 +1100 From: Peter Jeremy To: freebsd-net@freebsd.org Subject: IPv4 Multicast MAC Address issues Message-ID: <20140101085721.GA34334@server.rulingia.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="IJpNTDwzlM2Ie8A6" Content-Disposition: inline X-PGP-Key: http://www.rulingia.com/keys/peter.pgp User-Agent: Mutt/1.5.22 (2013-10-16) X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 01 Jan 2014 08:57:39 -0000 --IJpNTDwzlM2Ie8A6 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable I'm trying to use multicast on my home network for the first time and have found an apparent anomoly in the destination MAC address. My reading of RFC1112 section 6.4 is that the the destination MAC address uses the low 23 bits of the destination (multicast) IP address. This is what Linux and Windows do and ifmcstat(8) on FreeBSD shows that as the multicast MAC filter. Unfortunately, it seems that (at least on FreeBSD-10), the destination MAC address uses the low 23 bits of the IP address of my default route. I am not doing any special multicast-related configuration on any of the hosts and have been using ping(8) to generate multicast packets. Does FreeBSD need special configuration to support multicast or is this a bug? --=20 Peter Jeremy --IJpNTDwzlM2Ie8A6 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (FreeBSD) iKYEARECAGYFAlLD2HFfFIAAAAAALgAoaXNzdWVyLWZwckBub3RhdGlvbnMub3Bl bnBncC5maWZ0aGhvcnNlbWFuLm5ldDBCRjc3QTcyNTg5NEVCRTY0RjREN0VFRUZF OEE0N0JGRjAwRkI4ODcACgkQ/opHv/APuId8KACfcedqTHKmw7FD8iqMTOkc/XKe gdEAnRCKv9LSbWNp+r4fMRhQbOVmfKTI =8tEW -----END PGP SIGNATURE----- --IJpNTDwzlM2Ie8A6--