Date: Thu, 30 Apr 2015 22:06:58 +0100 From: "George Neville-Neil" <gnn@neville-neil.com> To: "Karlis Laivins" <karlis.laivins@gmail.com> Cc: "Eggert, Lars" <lars@netapp.com>, "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>, "grenville armitage" <garmitage@swin.edu.au> Subject: Re: Congestion Control Modification Message-ID: <8D3AEF2A-1413-4C44-9E5C-66900847F18A@neville-neil.com> In-Reply-To: <CAF4H_7=uV8ng-%2BY93wR88-aeW19HabaqR0iVkDXf6yujE4Wbpw@mail.gmail.com> References: <CAF4H_7mSGp_GZGaDBx8xq47FY1j85xLHq%2BZY1jMzprbzp%2Bg9zw@mail.gmail.com> <5535945F.90504@swin.edu.au> <CAF4H_7nOJP=Wy7LJSBi2PGupnMMvZu0xYeT2iYjhKDg-DPC6fw@mail.gmail.com> <F572540B-45C8-4EBF-9E18-7CA7E30CFD0C@neville-neil.com> <CAF4H_7=WZTmNUaS9x0DJh1YNRzFCJPbqJ_eFp12=z8snvTpn3g@mail.gmail.com> <98E7D40A-EC37-413D-85CE-2A6012811E08@netapp.com> <CAF4H_7=uV8ng-%2BY93wR88-aeW19HabaqR0iVkDXf6yujE4Wbpw@mail.gmail.com>
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If you want to run some experiments, though, you could look at running PTPd on 3 servers (master, and two slaves) which will get you decent synchronization among the three. Where decent is less than the typical RTT of a TCP packet on a 1Gbps LAN. Best, George On 30 Apr 2015, at 14:48, Karlis Laivins wrote: > Yes, you are correct, I meant to write "relative OWD". As David Hayes > put > it - "Relative OWD measurements are easier, and clock drift is not > usually > a problem over the time it takes to send and receive an ACK". > > Thank you for the correction! > > On Thu, Apr 30, 2015 at 4:19 PM, Eggert, Lars <lars@netapp.com> wrote: > >> On 2015-4-30, at 15:04, Karlis Laivins <karlis.laivins@gmail.com> >> wrote: >>> I have yet to solve the issue of >>> how to get the One Way Delay for the ACK message (the time it takes >>> ACK >> to >>> arrive from receiver of the ACK'ed data sender) correctly. >> >> That won't work without synchronized clocks, which you can't really >> assume >> to be present. >> >> Lars
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