From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mo4-p00-ob.smtp.rzone.de (mo4-p00-ob.smtp.rzone.de [85.215.255.23]) (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 0D4C93B29E for ; Sun, 19 Mar 2023 10:33:28 -0400 (EDT) ARC-Seal: i=1; a=rsa-sha256; t=1679236407; cv=none; d=strato.com; s=strato-dkim-0002; b=R3eCXp6ox9131Yjjh95el7AjWekU09kKhwvlan5O72BYHJSMenVoFD4mio3GwQtM98 4ndfGx6cIilqsUXVGqxxPOKnBexXQW1ZqEBDB0owtev+ep1Qhz+tL+scoEUiH9PSoqPc 8QkGwoPAdbjAiAsYvtww2OtK9Vmlhj7H8g/cKCmAJ3+a2wD4zNfQWgc70oUC+QGygYia NVL22xHcyO/Opjlhj10brwHUJrTn8zAdldA3tE+TDIUEtuITSNZloEnbNd1iL1nUNF4d Q/4P7B5YU2Wsi71wMCYi99fjaQp9R0J2mdriBIP/yj1nbw1KWrPRIetYyHXwQGrtoaUA SlBA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; t=1679236407; s=strato-dkim-0002; d=strato.com; h=In-Reply-To:From:References:To:Subject:Date:Message-ID:Cc:Date:From: Subject:Sender; bh=hsbsKwD07udZxblpTN8KQTEny0ooa7gbkyigWXnGLb8=; b=lFfZ7RqUvCVLBgrMMbnL4z0WSbwAklWHH9RE5EWok9Yg+lWmq9zOIOKN7KqR1HP1gc S875RGv4Bb9UGlJBicdR8+tX58fJ72GHQIgiaAraA5VJtiFCCs7LacaQlJHyvaWGFYnS AcoD2l/JwTcASU6sZ4ZzjxvEVZSVF6q1bbH93d1YhL2VN9w7YDu2cI8D1By+TJdVZMZb 3hnx3a8fx1Vc9Hrujb2Dsk6JEpSJ+Tn5lPShPnaXhHG41IiW8obDeglMu2BIr5fo3azf LdLSwcrUjQcFiArKCY1fGXdg6TLMsk8pX2jBMUx/MTHSPlJBtgs2qI5vJpBFF6CU2ZjB YHMw== ARC-Authentication-Results: i=1; strato.com; arc=none; dkim=none X-RZG-CLASS-ID: mo00 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1679236407; s=strato-dkim-0002; d=vdr.net; h=In-Reply-To:From:References:To:Subject:Date:Message-ID:Cc:Date:From: Subject:Sender; bh=hsbsKwD07udZxblpTN8KQTEny0ooa7gbkyigWXnGLb8=; b=D0E02/JXuXjxUArjPg81P8FE6ig7aSyiV8GmWv7Ga3GMUepdi3BSCAPfip/VHWz5CZ vB/u+JHyFSu7pJxfYJzPzSBeaBzhwy0ipwWiqom/vwSnhR52Q3fj5WtATO0E9k85ncbp gKpykOHL2NrDTzEVt60RhsD+WK2jN47r4WInTUsLg/prpOQtOby2LmLTXrdn688CYysT bBjc+oDfot7m/Ne08W7cbxIq0DRL87Y2PjfrBpgghdmW+vXOuhM4J18SX/JZ612iLrzI nzjyxFT44uX0y5wZMQPDC7sz3byjBuRIqlCaMNr5dEVmt+aYRow68tHo71MuF+lz6d9T dW4w== X-RZG-AUTH: ":L3oAZ2C+f+0rWOBO0o0FCt0K/NLK22L9vRfsowfGeUwc6mQXTJv7RSLWuaIv" Received: from [10.17.1.119] by smtp.strato.de (RZmta 49.3.1 DYNA|AUTH) with ESMTPSA id C5ca26z2JEXRMOf (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256 bits)) (Client did not present a certificate) for ; Sun, 19 Mar 2023 15:33:27 +0100 (CET) Message-ID: <94f8d9d8-75a4-0831-0a2e-020ac7175d12@vdr.net> Date: Sun, 19 Mar 2023 16:33:27 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Content-Language: en-GB To: starlink@lists.bufferbloat.net References: <20230319141619.GA1774@sunf68.rd.bbc.co.uk> From: Christian von der Ropp In-Reply-To: <20230319141619.GA1774@sunf68.rd.bbc.co.uk> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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 14:33:29 -0000 All-optical switching could greatly reduce complexity and power consumption on the satellites at the cost of flexibility. Up to 44 satellites in an orbital plane would use individual wavelengths which would be passed on transparently down the daisy chain and only satellites in range of gateways would convert the optical signals back into electrical ones, and send them down to earth while they pass a gateway. This would result in relatively short duty cycles, hence less power draw per orbit and less heat dissipation issues. Actually I've been suspecting that the SDA targets all-optical switching for the Transport Layer constellation as I don't seen any other immediate reason for the requirement of their OISL standard to require wavelength switching within the ITU channel grid for LCTs (see p. 18 of the OISL 3.0: https://www.sda.mil/wp-content/uploads/2022/04/SDA-OCT-Standard-v3.0.pdf) As a matter of fact tuneable wavelenghts were already required in the draft version of the OISL standard published in April 2020: https://twitter.com/Megaconstellati/status/1310336728595562499 -Christian Am 19.03.2023 um 16:16 schrieb Brandon Butterworth via Starlink: > 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 > _______________________________________________ > Starlink mailing list > Starlink@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/starlink