Month: October 2007

I found an interesting academic paper on the dilemma that Comcast faces with BitTorrent uploads: “The Interaction Between the DOCSIS 1.1/2.0 MAC Protocol and TCP Application Performance”:

“We have developed a model of the Data over Cable (DOCSIS) 1.1/2.0 MAC and physical layers using the ‘ns’ simulation package [2]. In previous work, we reported on the impact of several DOCSIS operating parameters on TCP/IP performance [3]. In this paper we extend those results by looking in greater detail at the impact that the MAC layer has on TCP performance when using the DOCSIS best effort service. We show that the interaction between DOCSIS and TCP exposes a denial of service vulnerability. By taking advantage of the inefficiency surrounding upstream transmissions, a hacker can severely impact network performance.”

In effect, several BT streams in the DOCSIS return path mimics a DoS attack to non-BT users. That’s not cool.

It turns out the war between P2P programs like BitTorrent and the typical network user is much larger than the current spat between the bandwidth hogs and Comcast. There’s an entire Wiki article on ways to avoid traffic shaping.

It includes a list of world-wide ISPs who try to keep the weeds out of the garden, and it’s long.

Despite the fact that P2P has some legitimate uses, such as distributing Freeware such as Linux, the fact remains that its primary uses are illegitimate, and even if they weren’t, the bandwidth it sucks out of cable modem networks inherently makes them less responsive for typical users. The answer to the load P2P puts on cable isn’t just “add more bandwidth” because the design of these networks is inherently asymmetrical. Adding massive amounts of new bandwidth is enormously expensive. Cable networks were designed on the assumption that the typical user does more downloading than uploading, but P2P violates that assumption.

So the only practical means of ensuring that P2P doesn’t drown out the typical user is to employ traffic shaping, and that gets the P2P freaks hopping mad. But there’s no free lunch, boys and girls, and somebody has to pay if everybody’s going to play.

While I was having fun demanding my own cables to everywhere, journalist Stephen Wellman of Information Week was making the same demand, for real:

I hate arguments that we as consumers are supposed to feel sorry for carriers when users start absorbing more bandwidth. Sorry, Comcast (and other service providers), get more bandwidth. Cable MSOs like Comcast tend to charge more than landline telecoms for their broadband, so why not spend some of that money on, you know, growing network capacity rather than on regulating a select group of users.

Jesus Christ. How are we ever going to have a dialog about the proper way to regulate the Internet while the tech press is full of idiots who think network bandwidth comes from Santa Claus? The simple fact is that no amount of additional bandwidth will satisfy the hogs: the more there is, the more they’ll use. Comcast understands this:

On another issue, [Comcast spokeswoman] Banse defended Comcast’s use of management technology, reported Friday by the Associated Press, to reduce the impact users of file-sharing networks, such as BitTorrent, eDonkey and Gnutella, have on overall traffic on the cable company’s pipe. While these users make up a small percentage of Comcast’s subscriber base, they account for a large majority of the traffic, Banse said.

“There is the hyperbole and the reality of what we call excessive use,” Banse said. While 99.9% of Comcast customers get access to the Internet without interference, the 0.1% that fit into the category of excessive use have to be managed. “In the (course) of our management of that excessive use, we call the customers and offer them the commercial service,” she said.

Predictably, Dave Isenberg is shamelessly demagoguing this issue:

Furthermore, once unencumbered by the need to use their network to advantage their own applications, network operators would be free to discover what Odlyzko found and what Internet 2 discovered [.pdf] — that the best way to manage congestion is simply to build more capacity!

Isenberg is full of shit wrong on at least two levels: The Internet2 experiment was conducted with routers two generations older than the ones we have now, and it was confined to a well-behaved population of users, all subject to Terms of Use imposed by their universities.

Universities today routinely apply bandwidth limits on their internal networks, especially the wireless ones. I know this because I designed and implemented such a system. People want them because bandwidth is neither free nor infinite, and the Internet lacks a mechanism to ensure that it’s shared equitably.

Isenberg knows this as well, but he deliberately ignores it because he makes his living stirring up brainless conflict. The network neutrality issue has been on life support for the past year, and only by confusing network management with the suppression of free speech can people like Isenberg hope to collect any additional speaker’s fees from it.

FURTHERMORE, it’s not clear to me that Comcast is doing what the critics allege they’re doing. I’m a Comcast customer, and at this very moment I’m running the Linux version of BitTorrent (Azureus) successfully for both uploads and downloads, legal and illegal. Here’s a screen grab to prove it (click the little image for the full-size copy.)

Unfortunate Internet regulation advocate Susan Crawford jumps aboard the Demagogue Train as well. That’s certainly no surprise, as Crawford wants to revive net neutrality and sees this as an opportunity. Here’s why she’s wrong:

Let’s posit that there’s a reasonable form of network management, which operates like this:

1) When demand for network bandwidth on shared facilities is low, every user gets as much as he wants.

2) When demand for network bandwidth exceeds supply, every user is allocated bandwidth equitably.

3) “Equitable” allocation means something like this: every user requesting less than the average per-user available bandwidth gets what he requests, and those who request more get additional bandwidth when it’s available.

That’s a reasonable algorithm implemented in a number of commercial systems today, and please note that’s it’s content- and viewpoint-neutral.

And also note that as a practical matter it’s only necessary to examine BitTorrent traffic on the typical ISP network to implement it, because (as a practical matter) all the excess demand for bandwidth comes from BitTorrent.

And also note that the slickest way to throttle BitTorrent is to limit the number of uploads a given user can offer, which is exactly what TCP Reset (RST flag) spoofing does.

Given all of that, is there anything to see here other than an ISP applying reasonable principles of network management by reasonable means?

Moral of the story: don’t believe everything Susan Crawford, Dave Isenberg, and their ilk tell you about the Internet. Much of it is made-up, and the rest is sensationalized.

Our worst nightmare has come true: the Internet, the sacred font of all that is holy, true, and/or pornographic, has been taken over by Evil Fat Cat Media Barons (maybe from outer space, maybe from New Jersey). No more shiny city on a hill, no more promised land, no more yearning to breath free: the Internet is dead, and freedom with it.

The last nail in the Internet’s coffin was hammered by Comcast, one of the many cable TV operators to offer a little Internet access on the side. Intrepid reporters from the Associated Press have learned that Comcast prevents Jimmy, the pimply-faced teenager next door, from sharing his pirated copy of the Paris Hilton sex tape with the sundry users of BitTorrent who learned he had it on the Pirate Bay web site.

The sober apologists for the phone companies claim this is simply “reasonable network management,” but we shouldn’t be fooled. Throttling bandwidth hogs is a completely unreasonable use of the laws of physics to stifle dissent. How dare Comcast limit the bandwidth hogs to ensure the rest of us can do a little web surfing! They have an obligation under the public trust to provide each and every one of us with all the bandwidth we can possibly consume, at no increase in price.

If the laws of physics say that each upload on a shared cable takes bandwidth away from every user, I saw screw the laws of physics. Give me my own cable to connect to every web site on the world, for no additional cost. If the fundamental design of the Internet calls for my sharing thousands of cables with millions of people and being a gentleman about it, I say sometimes you have a burn an Internet in order to save it.

The noble champions of freedom by regulation at Save the Internet are on the case:

Cable and phone companies like Comcast, AT&T and Verizon should not be allowed to play gatekeeper over their consumers’ ability to send or receive legal content over the Internet. It is time for Congress to pass laws that protect free speech on all 21st century communications.

Thank God for Save the Internet, one of the few organizations brave enough to stand up for the rights of the Jimmy the bandwidth hog (if you don’t count its parent, Free Press, or its benefactor George Soros, or his favorite charity Moveon.org (can I still mention their name without being stifled by Google?), or its contributors at Google, or their fellow fat cats at eBay, or their employee Craig Newmark, or the Christian Coalition, or the abortion people, or Arianna Huffington, Markos Moulitsas, Matt Stoller, or about a million other valiant opportunists, hucksters, and know-nothings.)

The cause of unlimited bandwidth at no additional price is going to be a hard sell, a tough slog, and an uphill climb. Legislative override of laws of physics is in its infancy and previous efforts haven’t gone well. Pi insists on remaining a fraction despite the Ohio Legislature’s efforts to reduce it to 3. But without this principle, our democracy will surely die.

I know this because I read it on the Internet.

But seriously, people, Comcast isn’t undermining any significant principle of free expression, network engineering, or customer relations. They’re applying a clever solution to one of the great unsolved problems of packet-switched networks (of which the Internet is one), the ability of users to consume more than a fair share of limited resources. Cable TV networks are especially vulnerable to this problem, because their means of sharing upstream bandwidth is highly inefficient. They download really fast, because there’s only one transmitter in the download direction, but they upload really slowly, because your cable modem has to negotiate with all of your neighbors for permission to transmit each portion of a packet. The reports indicate that Comcast’s policing takes effect after a certain number of BitTorrent transfers is found to be active, and prevents new ones from starting.

This is not content-based or viewpoint-based discrimination, in fact it’s the furthest thing from it. It is usage-based discrimination, and as long as it’s governed by an assessment of active traffic streams in the upload direction, it’s actually a step forward for network freedom. The punk next door limits my free speech with his incessant BitTorrent traffic much more than Comcast does.

The thing that’s so sad – predictable, but still sad – about the hysterical over-reaction to Comcast’s network management practices is that the people who are actually being helped by them are the first to allege harm from them. In some sense, they do so out of ignorance, but in another their motives are self-serving: they raise money by scaring people, and nothing scares like the poorly-understood practices of network engineering.

The gap between sound technical practice and the needs of advocacy groups to work ordinary citizens into a snit is the worst legacy of the network neutrality movement.

Here’s something to get the net neutrality movers excited: Level 3 Slashes CDN Prices

Level 3 Communications Inc. (Nasdaq: LVLT – message board) is lowering prices for content delivery network (CDN) services to match the same price customers pay for high-speed IP transport…

For now, the lower prices are for caching and downloading only. Level 3 hopes to have its streaming services ready by mid-November. That will allow the company to compete with Akamai, Limelight, and others not just for static and progressive media downloads, but for rich media streaming as well.

Isn’t this an example of a carrier leveraging its position as the handler of packets on the network to disadvantage competitors such as Akamai? The fact that the net result is lower prices to the consumer shouldn’t be lost amidst the irony about disadvantaging companies who sell disadvantage to other companies.

More on this later, but for now let’s not burden the Internet with too many restrictions on pricing and services, OK?