From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail1.bemta34.messagelabs.com (mail1.bemta34.messagelabs.com [195.245.231.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 9E7773B29E for ; Sun, 19 Mar 2023 10:16:23 -0400 (EDT) X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrDIsWRWlGSWpSXmKPExsXSsnPBFl1TSfE Ugw99OhZ7Np5ksVi7eAurA5PHzll32T22XzzDFMAUxZqZl5RfkcCacX7vIZaCTt6Ku8tXsjcw PuDqYuTiEBLYyCjRdqONGcKZzyhx7vpiVgjnJKPEq1Pr2SGcxYwSFxvvA5VxAjntjBIbT2mC2 CwCqhLfj91gBLHZBAwkJv78xwZiiwgoS0y5f4IdxGYWiJToOrMBLC4soCfR+HQJE4jNK2Au8e niGqiZARLNu6ezdDFyAMUFJf7uEIZo1ZK48e8lE0iYWUBaYvk/DhCTUyBQYtN+rQmMArMQ6mc hqZ+FUL+AkXkVo2lxalFZapGuuV5SUWZ6RkluYmaOXmKVbqJeaqlueWpxia6RXmJ5sV5qcbFe cWVuck6KXl5qySZGYCCnFCvP3MG4rO+v3iFGSQ4mJVFeiRDRFCG+pPyUyozE4oz4otKc1OJDj DIcHEoSvBIc4ilCgkWp6akVaZk5wKiCSUtw8CiJ8CYIAaV5iwsSc4sz0yFSpxgVpcR5F0gAJQ RAEhmleXBtsEi+xCgrJczLyMDAIMRTkFqUm1mCKv+KUZyDUUmY96A40BSezLwSuOmvgBYzAS2 +P0kEZHFJIkJKqoFpD5/BvVtvtsyOeni/Yub814/nP59dfNP1WnQh8+Waie6psgLdIVM7BIMW S96tVV1v+LpQoZ0x/7BQyISYi0oH5r1jiulemir7yKc1lU85e0/f8Rbux2mL/fOEtqa/bZygs LaB0ZRDM9V1SZ9F4fRLFfmb56byhriHW7/907H1QO1lp4UN4TcZ973lWMO8a7ei6rPaovlGVv Gf7GX73kWe/uD4ocb30fv939fOqJqbGFZ3yeRH1golE53yxR+clJWcKk5cOteuWX1go116WtC H2ISXM49U6vxWO5zw6ZHA8m2TrEyDec2/nHb8fPv8UpGfZ910f74sife5efTJ9XWujcbFa5ym N7Vc+DstLVZaiaU4I9FQi7moOBEA/v2hmF8DAAA= X-Env-Sender: brandon@rd.bbc.co.uk X-Msg-Ref: server-16.tower-570.messagelabs.com!1679235381!132722!1 X-Originating-IP: [132.185.160.180] X-SYMC-ESS-Client-Auth: outbound-route-from=pass X-StarScan-Received: X-StarScan-Version: 9.104.1; banners=-,-,- X-VirusChecked: Checked Received: (qmail 9782 invoked from network); 19 Mar 2023 14:16:21 -0000 Received: from mailout1.cwwtf.bbc.co.uk (HELO mailout1.cwwtf.bbc.co.uk) (132.185.160.180) by server-16.tower-570.messagelabs.com with ECDHE-RSA-AES256-GCM-SHA384 encrypted SMTP; 19 Mar 2023 14:16:21 -0000 Received: from gateb.lh.bbc.co.uk (gateb.kw.bbc.co.uk [132.185.132.11]) by mailout1.cwwtf.bbc.co.uk (8.15.2/8.15.2) with ESMTP id 32JEGLIW025108; Sun, 19 Mar 2023 14:16:21 GMT Received: from mailhub1.rd.bbc.co.uk ([172.29.120.129]) by gateb.lh.bbc.co.uk (8.15.1+Sun/8.13.6) with ESMTP id 32JEGL8a007756; Sun, 19 Mar 2023 14:16:21 GMT Received: from sunf68.rd.bbc.co.uk ([172.29.120.68]:36454) by mailhub1.rd.bbc.co.uk with esmtp (Exim 4.92) (envelope-from ) id 1pdtpd-0005Di-3v; Sun, 19 Mar 2023 14:16:21 +0000 Received: from sunf68.rd.bbc.co.uk (localhost [127.0.0.1]) by sunf68.rd.bbc.co.uk (8.13.8+Sun/8.12.2) with ESMTP id 32JEGKhd001970; Sun, 19 Mar 2023 14:16:20 GMT Received: (from brandon@localhost) by sunf68.rd.bbc.co.uk (8.13.8+Sun/8.12.2/Submit) id 32JEGKaZ001969; Sun, 19 Mar 2023 14:16:20 GMT Date: Sun, 19 Mar 2023 14:16:20 +0000 From: Brandon Butterworth To: Dave Taht Cc: Dave Taht via Starlink , brandon@rd.bbc.co.uk Message-ID: <20230319141619.GA1774@sunf68.rd.bbc.co.uk> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Starlink] mems optical switching X-BeenThere: starlink@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Starlink has bufferbloat. Bad." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 19 Mar 2023 14:16:23 -0000 On Sat Mar 18, 2023 at 03:19:49PM -0700, Dave Taht via Starlink wrote: > Today, this about google's mems switching tech hit, They've been talking about it since last year, seems to have got a hype bump recently. Who expected circuit switching to make a comeback? > I keep wondering where else it could be applied. They've been used for a long time, eg almost 20 years ago - https://archive.nanog.org/meetings/nanog32/presentations/zwart.pdf There is a goal of optical packet switching, until then you're limited to where there are limited flows of long enough duration to make the change from packet to circuit switching viable. So mostly automated testing. I've dabbled with the idea in an archive use case where very few of a large set of storage nodes need to connect to a moderate number of servers. For some cases we could have zero switches. The goal was a mostly dark infrastructure and many 1000s of storage nodes, removing the switches saves a lot of power. Commercial optical switches are expensive so I was looking at making an optical strowger as I wanted a high fan out not large n^2. In the mobile world they are looking at doing flexible bandwidth per node with coherent optics over gpon fibre plant, allocating variable amounts of spectrum to each, which could be adapted to a similar circuit model. It'd be no use to google as they want the full bandwidth between each node but as dwdm coherent optic costs come down you could imagine doing the same with a full channel between each pair, so like a conventional WSS but cheaper. If it wasn't for the optics cost I suspect they'd have done that reducing switching time to a channel change. brandon