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 298ED21F615 for ; Sat, 26 Jul 2014 04:18:51 -0700 (PDT) Received: from hms-beagle.lan ([134.2.89.70]) by mail.gmx.com (mrgmx003) with ESMTPSA (Nemesis) id 0MUILK-1X1kcK1TrW-00R0hb; Sat, 26 Jul 2014 13:18:34 +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: Sat, 26 Jul 2014 13:18:34 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: References: To: David Lang X-Mailer: Apple Mail (2.1878.6) X-Provags-ID: V03:K0:RIP9r2p2O/afPyA9PVHdA3XAT/pk5YvqG9LQ9+cIuq2hqVd0MNm fGe6pskJcXXmDrRbAVGBdFjCe+1W6hd27pQGq+vGuMaDrp076/g1gK05f9cFCoSrmoklA+B f7PQ4eyttLKWkxuZzm9fTsviWj1P5qf1FsyGqlzLvHWMzc6Q8UUxi54XkTWkEwkZ6vl1Fda lE0CVfTLqyyhOc7olavnw== Cc: Wes Felter , cerowrt-devel@lists.bufferbloat.net Subject: Re: [Cerowrt-devel] Ideas on how to simplify and popularize bufferbloat control for consideration. X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 26 Jul 2014 11:18:51 -0000 Hi David, On Jul 25, 2014, at 22:57 , David Lang wrote: > On Fri, 25 Jul 2014, Wes Felter wrote: >=20 >> The Netgear stock firmware measures bandwidth on every boot or link = up (not sure which) and I would suggest doing the same for CeroWRT. >>=20 >> Do you need to measure Internet bandwidth or last mile bandwidth? For = link bandwidth it seems like you can solve a lot of problems by = measuring to the first hop router. Does the packer pair technique work = on TDMA link layers like DOCSIS? >=20 > The trouble is that to measure bandwidth, you have to be able to send = and receive a lot of traffic. Well that is what you typically do, but you can get away with = less measurement traffic: in an ideal quiescent network sending two = packets back to back should give you the bandwidth (packet size / = incoming time difference of both packets), or send two packets of = different size (needs synchronized clocks, then difference of packet = sizes / difference of transfer times). > unless the router you are connecting to is running some sort of = service to support that, But this still requires some service on the other side. You = could try to use ICMP packets, but these will only allow to measure RTT = not one-way delays (if you do this on ADSL you will find the RTT = dominated by the typically much slower uplink path). If network = equipment would be guaranteed to use NTP for decent clock = synchronization and would respond to timestamp ICMP messages with = timestamp reply measuring bandwidth might be =93cheap=94 enough to keep = running in the background, though. Since this looks too simple there must be a simple reason why = this would fail. (It would be nice if ping packets with timestamps would = have required the echo server top also store its incoming timestamp in = the echo, but I digress) I note that gargoyle uses a sparse stream of ping packets to a = close host and uses increases in RTT as proxy for congestion and signal = to throttle down stream link=85 > you can't just test that link, you have to connect to something beyond = that. So it would be sweet if we could use services that are running = on the machines anyway, like ping. That way the =93load=94 of all the = leaf nodes of the internet continuously measuring their bandwidth could = be handled in a distributed fashion avoiding melt-downs by synchronized = measurement streams=85 Best Regards Sebastian >=20 > David Lang > _______________________________________________ > Cerowrt-devel mailing list > Cerowrt-devel@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cerowrt-devel