Netherlands Confirms: Cable lies less than DSL on speeds
Consumentenbond, a respected consumer group, finds that fewer than half of “20 meg” DSL subscriptions get even 10 megabits. http://bit.ly/7Nt944 This matches OFCOM's study in Britain, with cable generally within 20% and DSL often far worse. “Up to” advertisements are being misleadingly used around the world.

I'm guessing the KPN shortfall is because of long loop lengths, not congestion, but don't have the data. Ziggo cable delivered around 80% of promised speeds, and I bet some of the 20% shortfall was unavoidable system overhead, not congestion or similar problems. Most developed countries are dominated by large carriers with plenty of fiber backhaul, hence few congestion problems. Britain is going that way, with the big four taking over. Carphone, Sky, and Virgin are getting rid of their congestion problems, but smaller carriers who have to pay BT for backhaul often don't buy enough and bring down the average.

The U.S. is wildly confused about speeds ever since an FCC presentation said they typically were less than 50% of advertised. It turned out to be based on a mistake by Comscore, but has been often copied.

If a 3 megabit connection occasionally supplies more than 3 megabits, apparently Comscore assumed it was sold as six megabits. Verizon typically provides a safety margin by delivering more than 3 megabits and there apparently were many lines with occasional 3.3 megabit or similar measures that Comscore thought were bad six megabit but actually were excellent three meg connections. Since many U.S. DSL subscriptions are 1 meg or so and most of the rest 3 meg, those speeds will generally be achieved. In Holland, they apparently are selling similar lines as “up to 20 meg” and many deliver 2-10 meg because of distance.

Cable can in theory vary widely because of shared local loop, but most cablecos minimize the problem with network upgrades as needed. So the figure of “less than 20% degradation” is generally right. Much of that, in turn, is comparing a total loop speed with a measured IP throughput speed. The latter by definition includes substantial overhead, explaining most of the “reported” shortfall. My Time Warner cable modem is consistent at 10 meg down (except when it drops the whole connection because of a bad amplifier.)

Rudolf van der Berg worries that this will be the end of DSL in Holland. KPN has a deal with Reggefiber for fiber home, but that is deploying much more slowly than originally promised. Currently, UPC is advertising a 60 meg down triple play for 74 Euro, the same price KPN wants for an”up to 20 meg” DSL bundle with an inferior phone offering. “The headline item on every TV-news and news-website from morning to evening was that DSL consumers do not get what they pay for.” He reports customers are flocking from KPN to cable and that survey should accelerate that trend.

Van der Berg expects that trend will be limited by collusion between the telcos and cablecos to split the market, and that “cable and KPN will agree on a truce.” He provides reason to believe that's already happening in mobile. That's the current situation in the U.S., where 50 meg is costing $99 compared to less than $50 in both France and England. http://internetthought.blogspot.com/2010/01/end-of-dsl-is-nigh-but-collusion-will.html

The most surprising data was that UPC cable was only delivering 62% of the promised speeds. That's better than DSL but much worse than most cable companies. They were finishing their DOCSIS 3.0 deployment, so perhaps they hit a technical problem that is already being cleared. I've sent this over to Mike Fries to get the full story.