From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-we0-f171.google.com (mail-we0-f171.google.com [74.125.82.171]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 7B5AB200890 for ; Tue, 13 Mar 2012 20:08:04 -0700 (PDT) Received: by werm1 with SMTP id m1so2153740wer.16 for ; Tue, 13 Mar 2012 20:08:02 -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:content-transfer-encoding; bh=y6lUwJ69yzPOSnHqipnUsyHE3Amh9fCO247AB6sapek=; b=fJyVK+NX2ZOuSiEsJTWGWgs+r1ykj3Xq0ssKDlEROc114YafzrXZEzXqlQGWzUEodu WfeB11skdqRLexoAhx1JhpdIq4tyyM1wT2cu9Y2rKLiMiloL5GJdRxwroHjPMbLHFNo4 c9IvbCormioYAwzBavvT3D4vOpKGJHMYkViBZB/OqbFDN6ZFtqEHcx05pRo4yLOr3opw zLULCg1f/Az3t+uJQJLicr58f9pDh6rdnjBKUeXrFXdsR+yFhkgViYTil2ABiji2MdQa 4p6uasbsDn4QFGP0+UJNvLT8plkHJhvnrmuZuWnWE3iT2jSYbB6iEQa01kS05wb4WoR2 GNgw== MIME-Version: 1.0 Received: by 10.216.202.99 with SMTP id c77mr573241weo.5.1331694482515; Tue, 13 Mar 2012 20:08:02 -0700 (PDT) Received: by 10.223.151.8 with HTTP; Tue, 13 Mar 2012 20:08:02 -0700 (PDT) In-Reply-To: <4F5FF42B.9060900@c3energy.com> References: <20120313230612.GA24800@thyrsus.com> <4F5FF42B.9060900@c3energy.com> Date: Tue, 13 Mar 2012 20:08:02 -0700 Message-ID: From: Dave Taht To: "Ron Frazier (NTP)" Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: thumbgps-devel@lists.bufferbloat.net 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 03:08:04 -0000 On Tue, Mar 13, 2012 at 6:28 PM, Ron Frazier (NTP) wrote: > On 3/13/2012 9:10 PM, Dave Taht wrote: >> >> On Tue, Mar 13, 2012 at 4:06 PM, Eric S. Raymond =A0wro= te: >> >>> >>> Mike Hord: > I'd like to get a further minor clarification on the project goal. =A0Do = you > want your time reading to be within plus or minus 1 ms of UTC, for a tota= l > range of 2 ms? =A0Or do you want it to be within plus or minus 500 us of = UTC, > for a total range of 1 ms? Heh. Good question. As good as it is possible to get without having to have rubidium clocks embedded in the stick? Better than 10ms is desirable, and the 1ms is something of an arbitrary goal. Nyquist theorem applies, and then there's slop/noise elsewhere in the system that will start cropping up (interrupt latency, etc) Trying to clearly identify problem hops from multiple sides is dependent on the 'distance' inherent in the underlying technology. If we wanted to identify problems on a single 10GigE ethernet segment, that's measured in *ns*. We don't, thankfully. First hop out of a router is generally 1ms, same for wireless. Cable is in the 2ms-8ms range. DSL, up to 60ms, same for wimax... So < 5ms would be the outside goal, and anything less than that - so long as it can be thoroughly catagorized - is a bonus. Continental US distances are 60-100ms... > > 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. =A0I don't always see new messages very quickly. =A0If you need a > reply and have not heard from me in 1 - 2 weeks, send your message again.= ) > > Ron Frazier > timekeepingdude AT c3energy.com > > > _______________________________________________ > Thumbgps-devel mailing list > Thumbgps-devel@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/thumbgps-devel --=20 Dave T=E4ht SKYPE: davetaht US Tel: 1-239-829-5608 http://www.bufferbloat.net