From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f100.google.com (mail-la0-f100.google.com [209.85.215.100]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id EA62521F22D for ; Mon, 27 Apr 2015 02:54:53 -0700 (PDT) Received: by labgd6 with SMTP id gd6so2143944lab.2 for ; Mon, 27 Apr 2015 02:54:51 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:content-type:mime-version:subject:from :in-reply-to:date:cc:content-transfer-encoding:message-id:references :to; bh=94sdJspEr9FVdq8NwOvP6U9hhlxk+k+AZ5F/B9XKh8o=; b=h1VaZaRRljR++bzpPZAxOJcCSkHzyoAxgnUnrtStc8+cFt/GVVT8Wze2TUWG5s/waG rV1U5xqW1yAqBo6R3WFua2OJUGelErm2uIGX3wj/mFxLtwJxEvIkq5NUDl/PQhfbuUbL pVl+ucSmyUURJsIh4Pw3hUT4dBFecVb7C7pcwuz6t2A4Ft1sPJ7jH9RwJpXxPYdCqU+P mpOK6O6tA0JCHDPSImyvZEW1P0CuFqzx/OCB0kF5Dal+B7Q6cwQjD/nEMQX0AWzp1yGe 3oxQpEu3ViBNGh00ykPsTngTQiulP/gdT+hPXlnzRHUWYiaG/DZnG4tMNikscn63TIuO A4IA== X-Gm-Message-State: ALoCoQn3YvIGqxm6KojfSq7jDqYW22TSSbl7T9xbVwTHd1xvFkzIW5qWhpID/0vptBzbXAGlfy8MRai0TDIJC2+uhaogd01FRA== X-Received: by 10.194.104.164 with SMTP id gf4mr21328261wjb.102.1430128491234; Mon, 27 Apr 2015 02:54:51 -0700 (PDT) Received: from mail.la.pnsol.com (eu1sys200aog125.obsmtp.com. [207.126.144.159]) by mx.google.com with SMTPS id v6sm286291wix.0.2015.04.27.02.54.50 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Mon, 27 Apr 2015 02:54:51 -0700 (PDT) X-Relaying-Domain: pnsol.com Received: from mail.la.pnsol.com ([89.145.213.110]) (using TLSv1) by eu1sys200aob125.postini.com ([207.126.147.11]) with SMTP ID DSNKVT4HaQVolMMgLqvtK6237pjJnl3bGg2e@postini.com; Mon, 27 Apr 2015 09:54:50 UTC Received: from git.pnsol.com ([172.20.5.238] helo=roam.smtp.pnsol.com) by mail.la.pnsol.com with esmtp (Exim 4.76) (envelope-from ) id 1YmfkV-0001K3-4L; Mon, 27 Apr 2015 10:54:47 +0100 Received: from [172.20.5.110] by roam.smtp.pnsol.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1YmfkK-00007y-PM; Mon, 27 Apr 2015 09:54:36 +0000 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) From: Neil Davies In-Reply-To: Date: Mon, 27 Apr 2015 10:54:51 +0100 Content-Transfer-Encoding: quoted-printable Message-Id: <72DB0260-F0DF-426F-A3F3-ECF5D8AF228F@pnsol.com> References: To: Paolo Valente X-Mailer: Apple Mail (2.1878.6) Cc: bloat Subject: Re: [Bloat] Detecting bufferbloat from outside a node X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 27 Apr 2015 09:55:22 -0000 Paolo Yes, it is - there is a whole methodology for detecting this and = associated algebra for manipulation. It has been used at CERN, in = various telcos and in various large scale, real time distributed systems = to relate end user outcomes to the delay/loss characteristics of the = network. Take a look at http://www.pnsol.com/publications.html, you may find = http://www.pnsol.com/public/PP-PNS-2009-02.pdf as a good starting point. Neil On 27 Apr 2015, at 10:48, Paolo Valente = wrote: > Hi, > a network-monitoring company got curious about bufferbloat issues and = asked me to investigate a little bit the following issue (quite = interesting in my opinion). Is it possible to detect, from outside a = node, if the node is bufferbloated? In particular, the only action = allowed would be to observe the packets entering and leaving the node = (plus, of course, their timing). >=20 > If such a general problem is to hard or impossible to solve, do you = think it is still possible at least to understand, for some type of = application, if the application is experiencing a high latency because = of bloated buffers inside the node? (As above, by just observing packet = flows from outside the node.) >=20 > Thanks, > Paolo >=20 > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat