From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.perfora.net (mout.perfora.net [74.208.4.195]) by huchra.bufferbloat.net (Postfix) with ESMTP id 0192C20069D for ; Tue, 13 Mar 2012 18:28:14 -0700 (PDT) Received: from [192.168.83.5] (c-76-97-152-51.hsd1.ga.comcast.net [76.97.152.51]) by mrelay.perfora.net (node=mrus4) with ESMTP (Nemesis) id 0MRoq9-1RwGDV25pB-00TfNG; Tue, 13 Mar 2012 21:28:13 -0400 Message-ID: <4F5FF42B.9060900@c3energy.com> Date: Tue, 13 Mar 2012 21:28:11 -0400 From: "Ron Frazier (NTP)" User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.9) Gecko/20100722 Eudora/3.0.4 MIME-Version: 1.0 CC: thumbgps-devel@lists.bufferbloat.net References: <20120313230612.GA24800@thyrsus.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Provags-ID: V02:K0:EL6dm7B+l7/V2DCNBXKrP2yrO0x4eUE40kpo9qwQMiy pxsRZxYE2YueJfzLMjziz42xAbHt7dMdDlQVFHX/OQZzghX76o 6fJTBk2HD/g/ARc40BzKh+swfU6mETmWr07kYAFLHmvlUw+o+e LaxzypUjIUGW83ipvBr2xLKo1s09rqURzLxmtRzHHRWPPZIHmx ONVb+2D/ff5iVaMp+hXXVtWviiWdwZQs0Xrqlgp43iLv5o33GF WXmnrVg6gnGh9mCmbXe4xCBEnftzmzOF+6tk3B5WCYhpd3sTNm HZDTel4E7e3Hu2YOUVGTOF1RwthNSLbGzI9QztO2VZBKZQKKPf aWhjJC9tNr0+x8WYPW3PFg2qLm5TN4On7aTwFBZai Subject: Re: [Thumbgps-devel] Project clarification X-BeenThere: thumbgps-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 14 Mar 2012 01:28:15 -0000 On 3/13/2012 9:10 PM, Dave Taht wrote: > On Tue, Mar 13, 2012 at 4:06 PM, Eric S. Raymond wrote: > >> Mike Hord: >> >>> Can someone please clarify for me exactly what the aim is, however? I've >>> been unable to find a cohesive problem statement anywhere. From what I've >>> gathered, the idea seems to be to use the GPS timebase to provide a far >>> better gauge of time-of-flight (I'm not a network engineer; I don't know >>> what the real term would be) of a packet from one location on the internet >>> to another than current methods can provide. >>> > I LIKE your description! > > I also agree that things are confusing, this project was stalled out > for 9 months before it hit erics blog (after being locked in his > basement trying to make anything work for a week), and now this > list... > > A couple notes to tack onto esr's notes - > > 0) We've been trying to get something better than ntp or > gps-without-pps for a while now... the more accurate this can be made, > the smaller the error bars for time of flight. Right now the error > bars are in the half a diameter of the internet range (170ms) > > 1) jg and I were involved in olpc and one of my long term other > projects has been to finish spreading the internet around the world. > Doing that in many places gets hard. I was working on mesh networks, > and having small gpses actually on routers on the poles/trees/etc > would have helped a lot on finding the devices again. (this is > something of project creep, see 3). In the long run (after this > project!) I'm thinking something 'smile plug'-like+gps. > > I note that in that long run perhaps the gps feature will become > integral to outdoor wireless, as it has entered at least one product > line already: http://www.ubnt.com/rocketmgps > > 2) Having reliable time on or near boot down there is good (kerberos > needs 5 minutes, dnssec an hour, dhcp and routing daemons have time > dependencies), particularly as the reason for a boot is usually a > power failure that has taken out a sizeable chunk of the network. > > 3) While cbbd was originally conceived of as a way to fact-check ntp > beyond the edge, and be able to take a harder look at the data ntp was > filtering out, there seem to be other uses that we're blue-skying > about (I mentioned weather stations as one, gps+crypto as another), to > try and come up with something more unique. > > 4) But we circle back to trying to get down to 1ms resolution, or > better, on the other side of the network edge, as the core goal. > > I'd like to get a further minor clarification on the project goal. Do you want your time reading to be within plus or minus 1 ms of UTC, for a total range of 2 ms? Or do you want it to be within plus or minus 500 us of UTC, for a total range of 1 ms? Sincerely, Ron -- (PS - If you email me and don't get a quick response, don't be concerned. I get about 300 emails per day from alternate energy mailing lists and such. I don't always see new messages very quickly. If you need a reply and have not heard from me in 1 - 2 weeks, send your message again.) Ron Frazier timekeepingdude AT c3energy.com