[NNagain] The non-death of DSL

Sun Oct 8 03:14:38 EDT 2023

Hi Dave,

> On Oct 7, 2023, at 23:22, Dave Taht via Nnagain <nnagain at lists.bufferbloat.net> wrote:
> 
> I have a lot to unpack from this:
> 
> https://docs.fcc.gov/public/attachments/DOC-397257A1.pdf

Thanks for the link, I think this contains solid arguments for the FCC's current position. I for one am convinced that internet access is a game served well by having referees with "teeth".

> the first two on my mind from 2005 are: "FCC adopted its first open
> internet policy" and "Competitiveness"  As best as I recall, (and
> please correct me), this led essentially to the departure of all the
> 3rd party DSL providers from the field. I had found something
> referencing this interpretation that I cannot find right now, but I do
> clearly remember all the DSL services you could buy from in the early
> 00s, and how few you can  buy from now. Obviously there are many other
> possible root causes.

Since in other markets, introduction of NN/open internet regulations did not kill local loop unbundling this is IMHO not a strict consequence of sch regulations, but might be related to the exact process and scope of those regulations.

> 
> DSL continued to get better and evolve,

No shit, with sufficient short links G.fast offers capacity in the gigabit range, and up to 500m VDSL2 can deliver 100/40 Mbps...

> but it definately suffers from
> many reports of degraded copper quality,

For sure, once the cables are bad interference increases and achievable capacity drops quickly, and stability takes a hit.

> but does an estimate exist
> for how much working DSL is left?
> 
> Q0) How much DSL is in the EU?

This differs wildly by country, but here are some numbers for 2021 (which hence will likely over estimate the number of DSL links somewhat):
https://de.statista.com/statistik/daten/studie/303187/umfrage/anteil-der-dsl-anschluesse-an-allen-breitbandanschluessen-in-laendern-der-eu/

> Q1) How much DSL is left in the USA?

As option or as actually booked contract?

> Q2) What form is it? (VDSL, etc?)

I have no authoritative answer to Q1-3, but I can answer a Q4 (Amount of active access links per technology in Germany in 2022) you did not ask
see https://www.brekoverband.de/site/assets/files/37980/breko_marktanalyse_2023-1.pdf slide 11:
FTTH/B:	 3,400,000	: mostly PtMP GPON, a bit PtP AON ethernet, and some VDSL2 and G.fast (for in house distribution for some FTTB links)
HFC:	 8,700,000	: mix of DOCSIS 3.0 and DOCSIS 3.1, speeds up to 1000/50
VDSL:	19,500,000	: ITU G.993.5, VDSL2 with Vectoring and ITU G.998.4 G.INP, profile 17a (up to 100/40 Mbps) or 35b (up to 250/40 Mbps)
ADSL:	 5,200,000	: ITU G.992.5, stuck on ATM/AAL5, gross speeds up to 24/3.5, marketed speeds up to 16/3.5 Mbps

So for 2022 100 * (19.5+5.2)/(3.4+8.7+19.5+5.2) = 67.12% DSL (of around 37 million access links).

Germany is straggling behind in the FTTH roll-out compared to most other EU countries (see https://www.ispreview.co.uk/index.php/2023/04/2023-full-fibre-country-ranking-sees-uk-coverage-accelerate-vs-eu39.html), but except for the 5.2 million links still on ADSL most users have access to adequate access rates to participate in the digital society (~78% of access links have booked rates >= 30 Mbps, see breko_marktanalyse_2023).
I would guess that Germany is only partially representative for Europe as a whole, as I see a clear interaction between the incumbent's tech replacement cycle and the state of FTTH deployment. IMHO Deutsche Telekom started its last modernization a bit too early to jump on the FTTH train and hence opted for upgrading ADSL/non vectoring VDSL2 to vectoring VDSL2 to allow speeds of 100 Mbps to counter the DOCSIS thread (sure DOCSIS was always faster so the goal was IMHO not to fall behind too much).

I also note that the incumbent in Germany is forced by regulation to virtual local loop unbundling, which now a days in practice typically means competitors buy bit stream access (BSA)#, both the BSA and the incumbent's DSL prices are ex-ante regulated, that is they need regulatory acceptance before coming into effect. The regulator aims at setting these prices such that the wholesale prices reflects the estimated cost of building/maintaining the copper infrastructure and the incumbent's prices leave room for competitors to undercut the incumbent's prices while still making a surplus. (The ex monopolist incumbent still is the single largest ISP, neither the fact that the resellers are generally cheaper, nor the fact that DOCSIS is generally both cheaper and faster managed to change that*). I personally think that this regulation works pretty well, my only beef with it is that the regulatory agency seems unwilling to accept that the largest DOCSIS ISP (Vodafone) is also too large and should be submitted to a similar regulatory regime, but I digress.

All that said, Germany is on track to replacing the copper access network with FTTH in the next decade (it has proven to be one of these moving goals always a few years out in the future ;)).

Regards
	Sebastian

#) VDSL2 vectoring requires on vectoring unit to be in control of all links in a wire bundle, so does not really work with strict local loop unbundling (at least not when DSLAMs are moved out into the field closer to the end-customers as was done in Germany and the competitors want to offer competitive capacities); physical unbundling would require that an competitor would need to move its own active DSLAMs into each outdoor location of the incumbent (instead of before just in the CO); this is why the introduction of vectoring resulted in a re-centralization of DSL link ownership back to the incumbent (as they were willing and able to convert most DSLAMs to vectoring) hence the switch to bitstream access by the competitors. This worked OK even tough the competitors now lack the capability to differentiate themselves from the incumbent by using different technology.

*) My interpretation is that many customers do not care all to much as long as internet access simply works (fast enough, compared to what they know and expect) robustly and reliably.

> 
> Did competition in DSL vanish because of or not of an FCC related order?
> 
> -- 
> Oct 30: https://netdevconf.info/0x17/news/the-maestro-and-the-music-bof.html
> Dave Täht CSO, LibreQos
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