From owner-freebsd-questions@FreeBSD.ORG Thu Nov 24 10:07:10 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 EF809106566C for ; Thu, 24 Nov 2011 10:07:10 +0000 (UTC) (envelope-from kjkoster@gmail.com) Received: from mail-ww0-f42.google.com (mail-ww0-f42.google.com [74.125.82.42]) by mx1.freebsd.org (Postfix) with ESMTP id 87CA78FC0A for ; Thu, 24 Nov 2011 10:07:10 +0000 (UTC) Received: by wwo28 with SMTP id 28so403126wwo.1 for ; Thu, 24 Nov 2011 02:07:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=content-type:mime-version:subject:from:in-reply-to:date :content-transfer-encoding:message-id:references:to:x-mailer; bh=PJnMHpWGup04Jl9jJRe2A8ls6aZb4c7kASe/UU/v+Vw=; b=W+C8P7A0bw9wqJrzbirTcipIcvEDOEt9wm3p/e2/bjd+vv4i2iAH2pMfxv+r0PYqR8 F3nEuRJnFzdaux2xQAxRopkl9GwD1wGa0JWcdC6pfuHt56esWEVOccGl9zS8RpNVPqIl jCOcp3ZRe6r82p0fHNMV5atiMD6yLGLdGTFfk= Received: by 10.216.212.82 with SMTP id x60mr1038415weo.68.1322129229132; Thu, 24 Nov 2011 02:07:09 -0800 (PST) Received: from [10.0.135.191] (csp4.waag.org. [195.169.148.4]) by mx.google.com with ESMTPS id d17sm23655086wbh.19.2011.11.24.02.07.08 (version=TLSv1/SSLv3 cipher=OTHER); Thu, 24 Nov 2011 02:07:08 -0800 (PST) Content-Type: text/plain; charset=iso-8859-1 Mime-Version: 1.0 (Apple Message framework v1251.1) From: Kees Jan Koster In-Reply-To: <4ECC2CD0.8040902@sentex.net> Date: Thu, 24 Nov 2011 11:07:08 +0100 Content-Transfer-Encoding: quoted-printable Message-Id: <97326E87-B3A2-460F-AE9D-259710B36EA2@gmail.com> References: <4ECC2CD0.8040902@sentex.net> To: freebsd-questions@freebsd.org X-Mailer: Apple Mail (2.1251.1) 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 10:07:11 -0000 Dear All, Thank you so much for the excellent suggestions. I can tell some of you = have a lot of experience troubleshooting this issue. At this stage I ruled out hardware or network issues. These are server = grade network interfaces, new cables and the ifconfig configuration = seems in order. netstat shows no collisions or packet errors for the = past week or so. I am dead certain there is no dupe IP. The other machines on the switch = are currently off (test and load test box) and I still see packet loss. = There simply is no other machine on the subnet that might have the same = IP. 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 the = following: saffron (ip address a) -> cumin: packet loss saffron (ip address b) -> cumin: no packet loss cumin -> saffron (ip address a): packet loss cumin -> saffron (ip address b): no packet loss 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. Sooo.... Now what? I am completely at a loss. :-/ -- Kees Jan http://java-monitor.com/ kjkoster@kjkoster.org +31651838192 I hate unit tests; I much prefer the illusion that there are no errors = in my code. -- = Hendrik Muller