From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vn0-x22a.google.com (mail-vn0-x22a.google.com [IPv6:2607:f8b0:400c:c0f::22a]) (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 E30EF21F22A for ; Mon, 27 Apr 2015 08:25:36 -0700 (PDT) Received: by vnbg62 with SMTP id g62so12283100vnb.7 for ; Mon, 27 Apr 2015 08:25:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=IihDc59Q/BYryqJ2Wkq+KetY7MQJuB8lTIvcYx+3w5U=; b=u5tGovOB//sVAWxw74q4c/VI6Ci6ngL7HtYCayjZkW/ntn+nDAqS5gkYCAO9CKPK2H LYb9RxX0Wbmh0A2dZv1HAPvUFBLKHnRd3xtlmdyIjrxWoGEvxxr8y08ehRSEPweW2E6C rIaxoakoybIaikJFSfjxu1sdXNgRXvDvT44mJmDTmKQcdK3oXZ7F08Z8TQf5alusOSDA PQzDtANU0VRVBA98AAb0tl2B6NRsztyEz7NSQXX8HLCNavbZRYO5rPvcOjybLZG6yryh FIXTP7C5RM4LYcebig4Tzn2HAywsVrZk4KtNsM60WNUuir/02BjWBYMu25MuqAy8c+uT oE2g== MIME-Version: 1.0 X-Received: by 10.52.137.112 with SMTP id qh16mr27990276vdb.44.1430148333218; Mon, 27 Apr 2015 08:25:33 -0700 (PDT) Received: by 10.52.12.167 with HTTP; Mon, 27 Apr 2015 08:25:32 -0700 (PDT) Received: by 10.52.12.167 with HTTP; Mon, 27 Apr 2015 08:25:32 -0700 (PDT) In-Reply-To: References: <72DB0260-F0DF-426F-A3F3-ECF5D8AF228F@pnsol.com> Date: Mon, 27 Apr 2015 18:25:32 +0300 Message-ID: From: Jonathan Morton To: Paolo Valente Content-Type: multipart/alternative; boundary=bcaec52d599f60b22b0514b65bdf 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 15:26:10 -0000 --bcaec52d599f60b22b0514b65bdf Content-Type: text/plain; charset=UTF-8 One thing that might help you here is the TCP Timestamps option. The timestamps thus produced are opaque, but you can observe them and measure the time intervals between their production and echo. You should be able to infer something from that, with care. To determine the difference between loaded and unloaded states, you may need to observe for an extended period of time. Eventually you'll observe some sort of bulk flow, even if it's just a software update cycle. It's not quite so certain that you'll observe an idle state, but it is sufficient to observe an instance of the link not being completely saturated, which is likely to occur at least occasionally. - Jonathan Morton --bcaec52d599f60b22b0514b65bdf Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

One thing that might help you here is the TCP Timestamps opt= ion. The timestamps thus produced are opaque, but you can observe them and = measure the time intervals between their production and echo. You should be= able to infer something from that, with care.

To determine the difference between loaded and unloaded stat= es, you may need to observe for an extended period of time. Eventually you&= #39;ll observe some sort of bulk flow, even if it's just a software upd= ate cycle. It's not quite so certain that you'll observe an idle st= ate, but it is sufficient to observe an instance of the link not being comp= letely saturated, which is likely to occur at least occasionally.

- Jonathan Morton

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