From owner-freebsd-questions@FreeBSD.ORG Thu Nov 24 11:43:14 2011 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 95E81106566C for ; Thu, 24 Nov 2011 11:43:14 +0000 (UTC) (envelope-from m.seaman@infracaninophile.co.uk) Received: from smtp.infracaninophile.co.uk (smtp6.infracaninophile.co.uk [IPv6:2001:8b0:151:1:3cd3:cd67:fafa:3d78]) by mx1.freebsd.org (Postfix) with ESMTP id F243F8FC0C for ; Thu, 24 Nov 2011 11:43:13 +0000 (UTC) Received: from seedling.black-earth.co.uk (seedling.black-earth.co.uk [81.187.76.163]) (authenticated bits=0) by smtp.infracaninophile.co.uk (8.14.5/8.14.5) with ESMTP id pAOBhAIM069602 (version=TLSv1/SSLv3 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO) for ; Thu, 24 Nov 2011 11:43:10 GMT (envelope-from m.seaman@infracaninophile.co.uk) X-DKIM: OpenDKIM Filter v2.4.1 smtp.infracaninophile.co.uk pAOBhAIM069602 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=infracaninophile.co.uk; s=201001-infracaninophile; t=1322134990; bh=0Vsj5T6jw1h3K+5Isl/jURAkRJIh0SphaX8p7bYs5ag=; h=Message-ID:Date:From:MIME-Version:To:Subject:References: In-Reply-To:Content-Type:Cc; b=0AjGwzMFA+yfHgnt8ZAgXU7TiUwXcj3wLOOuZ9PwySkEx0eamkUtZW8q5jD3cUQDZ ij4hsvH8dgyNFAx8k1w7f2UIINGWxe2U4GurfgZvxhJzvD+gNtunGzCLHTcl5j7pd7 qaBf4JyhahnaKQbyZ6OqggnM1Ojec8oW5bopai2g= Message-ID: <4ECE2DC7.2000800@infracaninophile.co.uk> Date: Thu, 24 Nov 2011 11:43:03 +0000 From: Matthew Seaman User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:8.0) Gecko/20111105 Thunderbird/8.0 MIME-Version: 1.0 To: freebsd-questions@freebsd.org References: <4ECC2CD0.8040902@sentex.net> <97326E87-B3A2-460F-AE9D-259710B36EA2@gmail.com> In-Reply-To: <97326E87-B3A2-460F-AE9D-259710B36EA2@gmail.com> X-Enigmail-Version: 1.3.3 OpenPGP: id=60AE908C Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig59BA8DE6AF4D33CE8709854E" X-Virus-Scanned: clamav-milter 0.97.3 at lucid-nonsense.infracaninophile.co.uk X-Virus-Status: Clean X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,SPF_FAIL autolearn=no version=3.3.2 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on lucid-nonsense.infracaninophile.co.uk Subject: Re: Diagnosing packet loss X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 24 Nov 2011 11:43:14 -0000 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig59BA8DE6AF4D33CE8709854E Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 24/11/2011 10:07, Kees Jan Koster wrote: > This seems to be local to my machine. Here is another reason why I > say that: I can reliably transmit data when I bind to the aliased IP > address: If I use mtr to measure packet loss from saffron (the stricken= > machine) to cumin (another machine in a different data center) I see th= e > following: >=20 > saffron (ip address a) -> cumin: packet loss > saffron (ip address b) -> cumin: no packet loss >=20 > cumin -> saffron (ip address a): packet loss > cumin -> saffron (ip address b): no packet loss >=20 > This is consistent from running mtr for 5 minutes straight. This to > me shows that the hardware is fine. Using the alias IP address I can > run with no packet loss for as long as I like. >=20 > Sooo.... Now what? I am completely at a loss. :-/ Hmm... I wouldn't dismiss hardware problems just yet. Earlier you showed the ifconfig output for your problem machine: > [kjkoster@saffron ~]$ ifconfig bge0 > bge0: flags=3D8843 metric 0 mtu= 1500 > options=3D8009b > ether 00:e0:81:32:ed:b4 > inet 91.196.169.165 netmask 0xfffffff8 broadcast 91.196.169.167 > inet 91.196.169.166 netmask 0xffffffff broadcast 91.196.169.166 > media: Ethernet autoselect (100baseTX ) > status: active Where there is a one-bit difference between the addresses. Can you try temporarily using two even-numbered addresses and then two odd-numbered addresses and repeat your mtr tests? If the packet loss problem correlates with whether the address is even or odd, then I think that's pretty good evidence for a dud network interface: a one-bit problem in a memory register somewhere, occasionally flipping the least significant bit in the address to 0. Another test would be to swap the configuration order (ie. make .166 the primary address and .165 the alias) -- if it's always the first configured address that has problems, again that indicates memory trouble in the hardware. Are these NICs built-in to your motherboard? If so, they will almost certainly share a PHY, which is where the problem would be, and why swapping the cables between interfaces made no difference. Unfortunately in that case to fix the problem, you'll either have to swap out the motherboard or add a separate NIC card to your system. Hopefully the system is still under warranty. Cheers, Matthew --=20 Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard Flat 3 PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate JID: matthew@infracaninophile.co.uk Kent, CT11 9PW --------------enig59BA8DE6AF4D33CE8709854E Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.16 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk7OLc4ACgkQ8Mjk52CukIzsWACcCrgTA5U8feZeudCyeVO3nqe9 2PAAn0a5YFV2aGiD+5tfSLmxQ8dWGqJd =Q+d+ -----END PGP SIGNATURE----- --------------enig59BA8DE6AF4D33CE8709854E--