From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.tohojo.dk (mail.tohojo.dk [188.40.53.186]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id EE51921F199 for ; Mon, 17 Jun 2013 02:44:47 -0700 (PDT) Received: from alrua-desktop.borgediget.toke.dk (unknown [10.42.3.5]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.tohojo.dk (Postfix) with ESMTPSA id 95C5B1EC0D98; Mon, 17 Jun 2013 11:44:45 +0200 (CEST) Received: by alrua-desktop.borgediget.toke.dk (Postfix, from userid 1000) id D8B2CF418; Mon, 17 Jun 2013 11:44:44 +0200 (CEST) From: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= To: Sebastian Moeller References: <8738shsx3w.fsf@toke.dk> <87vc5drhdj.fsf@toke.dk> <87bo75rgp5.fsf@toke.dk> <8738shrd0p.fsf@toke.dk> <00B68282-44B0-4392-8AEF-68144A50D94E@gmx.de> Date: Mon, 17 Jun 2013 11:44:42 +0200 In-Reply-To: <00B68282-44B0-4392-8AEF-68144A50D94E@gmx.de> (Sebastian Moeller's message of "Mon, 17 Jun 2013 09:30:18 +0200") Message-ID: <87hagxnkad.fsf@toke.dk> User-Agent: Gnus/5.130008 (Ma Gnus v0.8) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha1; protocol="application/pgp-signature" Cc: cerowrt-devel@lists.bufferbloat.net Subject: Re: [Cerowrt-devel] trivial 6in4 fix(?) X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 17 Jun 2013 09:44:48 -0000 --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Sebastian Moeller writes: > Honestly, I think the best thing to do is not so much assume ATM or > lack of ATM, but simply measure it :) Right, doing the ping test with payload sizes from 16 to 113 packets gives me an almost completely flat ping time distribution ranging from 20.3 to 21.3 ms (see attached graphic). So probably I'm on PTM... > Easy to figure out empirically by hand, by finding the largest ping > packet size that still passes without fragmentation (see > http://www.debian.org/doc/manuals/debian-reference/ch05.en.html#_finding_= optimal_mtu) $ ping -c 1 -s $((1500-28)) -M do www.debian.org PING www.debian.org (128.31.0.51) 1472(1500) bytes of data. 1480 bytes from senfl.debian.org (128.31.0.51): icmp_seq=3D1 ttl=3D45 time= =3D114 ms =2D-- www.debian.org ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev =3D 114.522/114.522/114.522/0.000 ms $ ping -c 1 -s $((1500-27)) -M do www.debian.org PING www.debian.org (128.31.0.51) 1473(1501) bytes of data. From=2010.42.3.5 icmp_seq=3D1 Frag needed and DF set (mtu =3D 1500) =2D-- www.debian.org ping statistics --- 0 packets transmitted, 0 received, +1 errors So the MTU seems to be 1500 bytes. Now, how do I figure out what the PTM overhead is and feed it to HTB? :) =2DToke --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.20 (GNU/Linux) iQEcBAEBAgAGBQJRvtqKAAoJEENeEGz1+utPsVQH/2fmAWTwcWK5QgSwfMKBk+Nt DJfdwUnBBgZjhYdUrNp8iV7Hre18sg65JeufVvsWuNUyPWcbtLMccaVJdmyOdqZO HQ8CEc+wP1iF6L4dZNLh+2XloI/EcKVTh8NenBg++9pxqLr2fP2n9OyzbIA9XR7v XOZciU9vNA5rwCQnmle9dne3vjHGZf4WikeGee8KVn3Z6atphZ0QurYU+G1Od5yG P9L/PtOBZynkpHtiJb+kM89vJR19eRlQNt4EU1HqNuj8N+YaPGSSh6WHCZ7A76w3 krkMhOLJ6RqGxDdxSNAbmqDA4eRsqCIGG1CL9VpLyJNSrXOb5zzwNNVm8Bx98pE= =Rpih -----END PGP SIGNATURE----- --=-=-=--