From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from uplift.swm.pp.se (swm.pp.se [212.247.200.143]) (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 9B42F21F247 for ; Thu, 7 May 2015 00:19:55 -0700 (PDT) Received: by uplift.swm.pp.se (Postfix, from userid 501) id 97E8CA1; Thu, 7 May 2015 09:19:51 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=swm.pp.se; s=mail; t=1430983191; bh=Z+BKskvEOQF1gTLCKdduOKPN8Qohl6g5GtqLA5xwZCs=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=4MgKBGYlVLcURVwmMKq1EXtmKet2QH9yLZ5WWdkOkGkLkSUpYLX6treUKZ6zjHx2n MPXwe9qVpwlqkeu76zicf4lc2k1qpBzZnksQce2ph7fbCLEAfJ08FNUL+BtNigwjsm FHXnmx7qIvd7QJHEsPGUgkVHc0reXrFUlvAu56pg= Received: from localhost (localhost [127.0.0.1]) by uplift.swm.pp.se (Postfix) with ESMTP id 8EB9F9F; Thu, 7 May 2015 09:19:51 +0200 (CEST) Date: Thu, 7 May 2015 09:19:51 +0200 (CEST) From: Mikael Abrahamsson To: jb In-Reply-To: Message-ID: References: <553882D7.4020301@orange.com> <1429771718.22254.32.camel@edumazet-glaptop2.roam.corp.google.com> <6C0D04CF-53AA-4D18-A4E4-B746AF6487C7@gmx.de> <87wq123p5r.fsf@toke.dk> <2288B614-B415-4017-A842-76E8F5DFDE4C@gmx.de> <553B06CE.1050209@superduper.net> <14ceed3c818.27f7.e972a4f4d859b00521b2b659602cb2f9@superduper.net> <0C930D43-A05B-48E2-BC01-792CAA72CAD1@gmx.de> <5549A1B8.50005@superduper.net> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) Organization: People's Front Against WWW MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="-137064504-765979084-1430983191=:32169" Cc: Jonathan Morton , bloat Subject: Re: [Bloat] DSLReports Speed Test has latency measurement built-in 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: Thu, 07 May 2015 07:20:24 -0000 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---137064504-765979084-1430983191=:32169 Content-Type: TEXT/PLAIN; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8BIT On Thu, 7 May 2015, jb wrote: > I am working on a multi-location jitter test (sorry PDV!) and it is > showing a lot of promise. For the purposes of reporting jitter, what > kind of time measurement horizon is acceptable and what is the +/- > output actually based on, statistically ? > > For example - is one minute or more of jitter measurements, with the +/- > being the 2rd std deviation, reasonable or is there some generally > accepted definition ? > > ping reports an "mdev" which is > SQRT(SUM(RTT*RTT) / N – (SUM(RTT)/N)^2) > but I've seen jitter defined as maximum and minimum RTT around the average > however that seems very influenced by one outlier measurement. There is no single PDV definition, all of the ones you listed are perfectly valid. If you send one packet every 20ms (simulating a g711 voip call with fairly common characteristics) at the same time as you send other traffic, and then you present max, 99th percentile, 95th percentile and average pdv, I think all of those values are valuable. To a novice user, I would probably choose the 99th and/or 95th percentile PDV value from baseline. -- Mikael Abrahamsson email: swmike@swm.pp.se ---137064504-765979084-1430983191=:32169--