From owner-freebsd-net@FreeBSD.ORG Fri May 1 05:21:23 2015 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 09AC6675 for ; Fri, 1 May 2015 05:21:23 +0000 (UTC) Received: from mail-lb0-x229.google.com (mail-lb0-x229.google.com [IPv6:2a00:1450:4010:c04::229]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 7F20516C6 for ; Fri, 1 May 2015 05:21:22 +0000 (UTC) Received: by lbbuc2 with SMTP id uc2so59333401lbb.2 for ; Thu, 30 Apr 2015 22:21:20 -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; bh=rxDkQ19ZtGr4s08dGbLOYmyL2uYcrtkRi9JrzM8hfXw=; b=QIb8lI0cJUSejMf6ZoVWaX0CmBY/19UDc38wBIezuoUDB5beXxoCGE6UVFYn0cE8gc +ONcae8vNLsLjOijBcbP2/WzTEQluugupBZ04YbLtEc3P+xiui6ktRwBVwiRyOw7f33n uYFpe1vDMl/9ZlRW4r3Rfbvqq7UKl6I4s0RhmKYzGw0nC2HHlebL6Uw6x5d+il8cr/5l bTP6THnfxrvNYsRllHylg0S+sZN+cspLTchBj9/OYacdC0M8dcShkVbdvi8xiBBlgddD OfRjLG0crjowcZBkRVF3vTc0hpdpFGnW5pW4E2vrcbpDKwP0RuqlNQs4wk2pku+F3Uf3 yLxA== MIME-Version: 1.0 X-Received: by 10.112.29.180 with SMTP id l20mr6553240lbh.95.1430457680645; Thu, 30 Apr 2015 22:21:20 -0700 (PDT) Received: by 10.114.202.229 with HTTP; Thu, 30 Apr 2015 22:21:20 -0700 (PDT) In-Reply-To: <8D3AEF2A-1413-4C44-9E5C-66900847F18A@neville-neil.com> References: <5535945F.90504@swin.edu.au> <98E7D40A-EC37-413D-85CE-2A6012811E08@netapp.com> <8D3AEF2A-1413-4C44-9E5C-66900847F18A@neville-neil.com> Date: Fri, 1 May 2015 08:21:20 +0300 Message-ID: Subject: Re: Congestion Control Modification From: Karlis Laivins To: George Neville-Neil Cc: "Eggert, Lars" , "freebsd-net@freebsd.org" , grenville armitage Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.20 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 01 May 2015 05:21:23 -0000 Hello George, Thank you for the tip! I have set up a virtual test environment with IMUNES (interesting tool, by the way) and now I am running validation tests, to see, if the results there are at least similar to those that can be achieved on a physical testbed. I will let you know if and when the implementation will be done as I will certainly need objective feedback. BR, Karlis On Fri, May 1, 2015 at 12:06 AM, George Neville-Neil wrote: > 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 wrote: >> >> On 2015-4-30, at 15:04, Karlis Laivins 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 >>> >>