From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from secmail.pch.net (secmail.pch.net [206.220.231.87]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id DC72C3CB38 for ; Fri, 19 Jan 2024 02:26:21 -0500 (EST) Received: from secmail.pch.net (localhost [127.0.0.1]) by secmail.pch.net (Postfix) with ESMTP id 4TGWPn0h7sz4xVTc for ; Thu, 18 Jan 2024 23:26:21 -0800 (PST) Authentication-Results: secmail.pch.net (amavisd-new); dkim=pass reason="pass (just generated, assumed good)" header.d=pch.net DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=pch.net; h= x-mailer:to:references:message-id:content-transfer-encoding:date :in-reply-to:from:subject:mime-version:content-type; s= secmail_dkim; t=1705649179; x=1708241180; bh=ab7PcQMxSr38BXSjDWN TmEeBCvzgXJLSCLxRPHedzFQ=; b=T06ijXY01jRDkXnFlfFthBr/tDVa0UyPsI0 /tKFnaMqGS4NQXfQdvzgGoPJsbaxJQsrQESg3oZRxpVltr+hRbKorRhTTy+WOO6b omFRsiAE5PDx82mTegtSHhILDQ0Ms1QvQlx4yiEM6/1q6AqQUF/vexl9H98r5hOq aT/D4kFjxhiLzzrPeoyuV02z1ISPTsVYKZmlaZ3unv44xNZlj4ZjbpbKbZMpp0Q2 EMx8KdPU+MOtvpGRJZt9bVujNdKXpZ9VERK0S9CbokkxayfGZR2/P639doX2Ebjr y30GJS75nIzguXXkMuKsv7t+PLFCdPolrRqEZGQnLueiNWQnHfw== X-Virus-Scanned: amavisd-new at secmail.pch.net Received: from secmail.pch.net ([127.0.0.1]) by secmail.pch.net (secmail.pch.net [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id 0sQnavnbz8Qw for ; Thu, 18 Jan 2024 23:26:19 -0800 (PST) Received: from smtpclient.apple (unknown [66.185.123.190]) by secmail.pch.net (Postfix) with ESMTPSA id 4TGWPl23Bgz4xVTZ; Thu, 18 Jan 2024 23:26:19 -0800 (PST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.400.31\)) From: Bill Woodcock In-Reply-To: Date: Fri, 19 Jan 2024 08:26:17 +0100 Cc: =?utf-8?Q?Network_Neutrality_is_back!_Let=C2=B4s_make_the_technical_as?= =?utf-8?Q?pects_heard_this_time!?= , thejoff@gmail.com Content-Transfer-Encoding: quoted-printable Message-Id: <7D4F20E7-F4A8-44C2-BDF5-A666CF7C94FB@pch.net> References: To: Sebastian Moeller X-Mailer: Apple Mail (2.3774.400.31) Subject: Re: [NNagain] are you Bill Woodcock? X-BeenThere: nnagain@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: =?utf-8?q?Network_Neutrality_is_back!_Let=C2=B4s_make_the_technical_aspects_heard_this_time!?= List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 19 Jan 2024 07:26:22 -0000 > On Jan 19, 2024, at 08:14, Sebastian Moeller wrote: >> On 18. Jan 2024, at 23:38, Bill Woodcock via Nnagain = wrote: >> So, if one Internet user wants to talk to another Internet user, = generally they hand off their packet to an Internet service provider, = who takes it to an exchange, and hands it off to another Internet = service provider, who delivers it to the second user. When the second = user wants to reply, the process is reversed, but the two Internet = service providers may choose a different exchange for the hand-off: = since each is economically incentivized to carry the traffic the = shortest possible distance (to minimize cost, speed x distance =3D = cost), the first ISP will always choose the IXP that=E2=80=99s nearest = the first user, for the hand-off, leaving the second ISP a longer = distance to carry the packet. Then, when their situations are reversed, = the second ISP will choose the IXP nearest the second user, leaving the = first ISP to carry the packet a longer distance. >=20 > I would propose a slight modification, "each is economically = incentivized to carry the traffic the shortest possible distance" is not = free of assumptions... namely that the shortest path is the cheapest = path, which is not universally true. Correct. That=E2=80=99s a simplification of a complex field where = distance and cost are frequently intermingled, and routing decisions are = typically based on latency, overridden by cost as a matter of policy. = However, in a simplified or idealized case, if speed is held constant, = distance and cost scale together, so they are usually held to be = interchangeable in decision-making in the general case. Speed x = distance =3D cost. > My personal take is "routing follows cost" that is it is money in the = end that steers routing decisions Yes, exactly. The primary case in which routes follow a cost that differs from = distance is in the preference for distant downstream transit over nearby = peers, and distant peers over nearby upstream transit. Though it=E2=80=99= s uncommon in networks of small geographic scale, most global-scale = networks do this, and it=E2=80=99s the cause of many routing problems = and loops. > ...at least once we include paid peering... That=E2=80=99s a marketing euphemism for transit. > My ISP aggregates its customers in a handful of locations in Germany, = Hamburg in my case while I actually live a bit closer to Frankfurt than = Hamburg, so all traffic first goes to Hamburg even traffic to Frankfurt = (resulting in a 500-600 Km detour), I assume they do this for economic = reasons and not just out of spite ;)=20 Essentially all mobile network operators do this. It=E2=80=99s = generally a matter of incompetence and lack of competition, rather than = spite or economic reasons. > Now, maybe the important point is, this does not involve IXPs so might = be an orange to the IXP apple? Yes, only indirectly. Most of what you=E2=80=99re discussing involves = non-optimal outbound IXP selection, one quarter of the round-trip path. = Very real issues, but not anything an IXP or receiving-side ISP can do = much about without second-guessing routing decisions to an impractical = degree. -Bill