From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.18]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mout.gmx.net", Issuer "TeleSec ServerPass DE-1" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 5ED7721F5AE for ; Mon, 25 Aug 2014 12:12:41 -0700 (PDT) Received: from hms-beagle.home.lan ([217.86.104.125]) by mail.gmx.com (mrgmx003) with ESMTPSA (Nemesis) id 0MhiTL-1WzFuj3iyp-00Mug9; Mon, 25 Aug 2014 21:12:35 +0200 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) From: Sebastian Moeller In-Reply-To: Date: Mon, 25 Aug 2014 21:12:31 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: References: <000001cfbefe$69194c70$3b4be550$@duckware.com> To: Jim Gettys X-Mailer: Apple Mail (2.1878.6) X-Provags-ID: V03:K0:jLaZlCROKmg3BrmYYT8nj1KX0bAKqyszll21Tt05Eh9ALvjo7Ys 2+BD3gOm2+Aiqj8m9phWQnZ3iLH276SVNFe//DgpAd3KaVAGTF+qYdXtuna1h6Pgc1CD8yw ciLVUFA4og9drSeyRd5a1+1hTdt8FXDQTJyrlfIUjMQjaeAOhPyXaLwpzfPCjAEtCYbyOz4 jM6DpmRC9LMkV1us43N1g== X-UI-Out-Filterresults: notjunk:1; Cc: "bloat@lists.bufferbloat.net" Subject: Re: [Bloat] The Dark Problem with AQM in the Internet? 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, 25 Aug 2014 19:12:41 -0000 Hi Jim, On Aug 25, 2014, at 20:09 , Jim Gettys wrote: > Note that I worked with Folkert Van Heusden to get some options added = to his httping program to allow "ping" style testing against any HTTP = server out there using HTTP/TCP. >=20 > See: >=20 > http://www.vanheusden.com/httping/ That is quite cool! >=20 > I find it slightly ironic that people are now concerned about ICMP = ping no longer returning queuing information given that when I started = working on bufferbloat, a number of people claimed that ICMP Ping could = not be relied upon to report reliable information, as it may be = prioritized differently by routers.=20 Just to add what I learned: some routers seem to have rate = limiting for ICMP processing and process these on a slow-path (see = https://www.nanog.org/meetings/nanog47/presentations/Sunday/RAS_Traceroute= _N47_Sun.pdf ). Mind you this applies if the router processes the ICMP = packet, not if it simply passes it along. So as long as the host = responding to the pings is not a router with interesting limitations, = this should not affect the suitability of ICMP to detect and measure = buffer bloat (heck this is what netperf-wrapper=92s RRUL test = automated). But since Jerry wants to pinpoint the exact location of his = assumed single packet drop he wants to use ping/traceroute to actually = probe routers on the way, so all this urban legends about ICMP = processing on routers will actually affect him. But then what do I = know... Best Regards Sebastian > This "urban legend" may or may not be true; I never observed it in my = explorations. >=20 > In any case, you all may find it useful, and my thanks to Folkert for = a very useful tool. >=20 > - Jim >=20