[Cerowrt-devel] [Bloat] the future is in high speed symmetrical internet speeds!!!!

Wheelock, Ian ian.wheelock at commscope.com
Tue Jul 6 06:43:02 EDT 2021

I agree on Sebastian’s points on DOCSIS being able to offer this 100/100 service, as well as what the most recent version of what DOCSIS can do..

In terms of DOCSIS 3.1 it supports “High Split” upstream where signals operate up to 204MHz (from current limits of 42MHz, 65MHz or 85MHz). This is equivalent to 1.35Gbps in the US direction. In terms of DS direction, the copper coax is capable of up to 6GHz operation, with Full Duplex DOCSIS (FDX) and Extended Spectrum DOCSIS (ESD) already positioned for 1.8GHz and 3GHz.

For 204MHz US operation, there are some plant modifications required (where some amps and diplexers need to be upgraded to the higher frequencies). D3.1 chipsets introduced in 2015 (and still used) have the hardware capability to utilise this extra upstream spectrum (2x 192MHz DS OFDM & 2x 96MHz US OFDMA along with legacy SC-QAM support (24/32 DS & 8 US). However, the modems deployed in production are designed for different spectrum plans depending on operator cable plant – meaning a modem might only support 65MHz or 85MHz US – although some were designed to allow software modify the frontend, physically switching between 85MHz US to 204MHz, so as to enjoy the extra capacity once the plant upgrade was completed (upgraded on a per “service group” basis).

DOCSIS3.1 (current deployed tech) is well positioned to offer 100/100 symmetric services with existing HW on both ends of the coax. DOCSIS 4.0 (active developments) will go well beyond that level…

DOCSIS3.1 capacity of the network is up to 2Gbps US and 10Gbps DS
DOCSIS4.0 FDD/ESD capacity is up to 5Gbps US & 10Gbps DS
While beyond FDD/ESD the copper carrying capacity is up to 10Gbps US and 25Gbps DS.

Ian Wheelock

From: Bloat <bloat-bounces at lists.bufferbloat.net> on behalf of Sebastian Moeller <moeller0 at gmx.de>
Date: Monday 5 July 2021 at 22:21
To: Dave Täht <dave.taht at gmail.com>
Cc: cerowrt-devel <cerowrt-devel at lists.bufferbloat.net>, bloat <bloat at lists.bufferbloat.net>
Subject: Re: [Bloat] [Cerowrt-devel] the future is in high speed symmetrical internet speeds!!!!

Hi Dave, Well, less asymmetric down/up ratios are certainly worth fighting for (for one NTP should work better). And, as I might add, something that is orthogonal to better router software ;) a fast s
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Hi Dave,

Well, less asymmetric down/up ratios are certainly worth fighting for (for one NTP should work better). And, as I might add, something that is orthogonal to better router software ;) a fast symmetric link with a craptastic router is still roughly as much fun as a dial-up connection with the best router software we can wish for... ;)

Regarding that EFF article, while I think that light over fiber is "the obvious way forward", I fear that the strategy of asking for 100/100 under the assumption, it can only be reliably achieved by fiber roll out, ignores the full duplex technologies that are either ready for deployment (full duplex g.fast) or a much cheaper plant upgrade away than rolling our new fiber (full duplex docsis comes to mind, which might require changes to the physical plant layout with nested/hierarchical amplifiers*). I note that local docsis ISPs in Germany are aiming for 100 Mbps upload in the next 12-24 months (simply by switching more upload spectrum to docsis 3.1 coding schemes). In short 100/100 might not be the "only with fiber" speed grade the authors seem to think, and if the goal is full fiber than it seems best to actually require full fiber.

Best Regards


*) Or not might be possible to run full duplex over some level of hierarchical amplifiers...

> On Jul 5, 2021, at 20:46, Dave Taht <dave.taht at gmail.com> wrote:


> or at least, in more politicking, for fiber.


> https://secure-web.cisco.com/1op2p3QHW9dBXc6FToJpSSHJVJ2ZeNLnznAfItKhgE0dEFSvu00sPOc9vrlKBd1HeF_ONtZFQzsk1clpw9UrhmYCGFNC_FiNO0UH9-93snFlf42DxvkBZKrws8xQCyDxE0UNssak4EgQrp6sfE-bbovjveL5pDIUF0I1QJ-ntnPgQ5ovwZDcZDFHwlZTBI3bBHb5qDlJQtxzo8_XEmkjdynTJ8UE9u70LzBUTe3_xiA6yUIInrr5IPjwTJBXewegkCvmAAxQHCQ1OGe8pxs80GUCkGIHQy1YEmcOGUEjqtIFklI7ADKXqCmO2tWg0um4SwgNqXhLMx4iSz79culZJLw/https%3A%2F%2Fwww.eff.org%2Fdeeplinks%2F2021%2F07%2Ffuture-symmetrical-high-speed-internet-speeds


> I emailed the authors and mentioned that better routers might be a

> cheaper start...


> --

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