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Bittorrent To Cause Internet Meltdown
Gimble writes "Richard Bennett has an article at the Register claiming that a recent uTorrent decision to use UDP for file transfers to avoid ISP 'traffic management' restrictions will cause a meltdown of the internet reducing everybody's bandwidth to a quarter of their current value. Other folks have also expressed concern that this may not be the best thing for the internet."
There's no way that BT's protocol could be as sophisticated as TCP, given its 30+ years of development. Most people don't appreciate how amazingly well TCP's flow control works in terms of maximizing link utilization in a way that is fair to all network users. We really don't need is an arms race of new, greedier protocols.
TCP gets a lot of credit it doesn't deserve. It enforces bad design -- most client/server applications should be either stateless or session-based, rather than connection-oriented. Anything that even vaguely resembles a streaming application shouldn't even consider TCP. Finally, TCP's connection model is almost guaranteed to be suboptimal for any application that does require one.
What are the odds that HTTP, FTP, SMTP, and BitTorrent will all work optimally over TCP? Slim to none, and none is still waiting for Nagle.
Sounds like the ISPs should have used the tax incentives we gave them to increase network capacity and reach to, you know, increase network capacity and reach. If they had done that years ago to keep pace with the growth of their network traffic, they wouldn't be in this situation.
But no, of course, it has to be the person who uses their connection's fault.
I pay for a pipe. My ISP should take no interest in the source or destination or type of service connections in this pipe. Anything else is just allowing the system to be used abusively.
It isn't appropriate for legitimate bittorrent users to be driving other TCP off the network.
The only way the BitTorrent use can drive other users off to the network is if the ISP's network is misconfigured or is being overutilized due to too much overselling (you have to have some overselling, not everyone is on 24/7). ISPs that have their shit together will have their network designed to handle expected and future traffic growth such that all of their customers can use what they paid for.
you just want to bully other people out of their bandwidth so you get more
They paid for their bandwidth and I paid for mine. I have a cap on my connection speed; they do as well. The only difference is that their YouTube videos load instantly and my BitTorrent transfer is knee-capped. Who is the bully here?
This isn't the right way for BitTorrent to move forward
What is the right way to move forward? Accept that there are two levels of Internet traffic: "clean, good, wholesome non BitTorrent traffic" and "dirty, evil, corrupting BitTorrent traffic"?
To say that TCP is optimal at dealing with congestion is to say that individual packets are always a good representation of the data blocks being sent and received at the application level, and that best thing that any application can do when expected data doesn't arrive is to wait on it to be retransmitted, with the network layer queuing up all subsequent intact packets.
Once again, this behavior is guaranteed to be completely wrong for anything but toy command-line applications that fit on a single page in the back of a musty-smelling manual.
Not really. You would need that if you were transferring a file from one computer to another. But Bittorrent scrapes together little bits of file from lots of other computers. If a packet is lost here and there, that bit of file is naturally requested again, probably from a different machine. That's just a consequence of the way Bittorrent works.
That behavior needs to be driven by some timing and retry logic. Also, hosts need to determine how fast they can fire these UDP packets at each other. Those are the most basic fundamentals of transmitting bulk data over a packet network. You really would be reinventing some subset of TCP.
I think what he's trying to say is the TCP connection often gets dropped completely, for example the host just goes offline, or is bogus and transmitting false data. Bittorrent needs to account for this anyway by re-requesting packets from the network, so they have implement the retry logic differently that TCP anyway.
that Car Dealer thing is a terrible analogy. With the ISP model, everything you do with the 'bandwidth' you paid for goes through *their* systems first - they're understandably concerned that the drugs you're running across their borders are going to reflect badly on them in the long run.
"that Car Dealer thing is a terrible analogy. With the ISP model, everything you do with the 'bandwidth' you paid for goes through *their* systems first - "
Which is bullshit, consider the post office, I order something online from a retailer, does this give the shipping company or government the right to open my mail and packages because it passes through their facilities? It's bullshit plain and simple. They don't have a right to watch and monitor what you send. It's just another cash grab disguised as "helping the consumer"
16 linecards at 50k each, for 800,000. Lets call it a cool mill in asset costs.
30k subscribers paying $20 each a month. $600,000 a month. $7.2 mill a year.
Yeah, I can see how the initial sticker value of a 2 router closet is going to a road to ruin for most ISPs.
I don't think ISPs are cash cows by any means, once you consider opperating expenses and labor. But a $1 million dollar switch station can be easily amorted out over a 5 year loan when the ROI on that million is quite solid.
-Rick
"Most people in the U.S. wouldn't know they live in a tyrannical state if it walked up and grabbed their junk." - MyFirs
The problem with bittorrent, is that it's MORE convenient than watching TV the old fashioned way. All the benefits of TIVO, except that I can use my computer (and keyboard) to specify which shows I want. I don't care which channels are broadcasting them, they just appear in the downloaded folder. I can watch from any computer in the house (or outside with a laptop). There are no DRM restrictions.
The author of this article could have called or emailed Bram Cohen before writing this article, but then he wouldn't have had such sensational tripe to garner page views. If he had, he would have known that he has got it completely wrong. The switch to uTP is actually to make BitTorrent traffic more friendly to Internet traffic. You see, BitTorrent is trying to sell a content delivery service based on their client and the #1 complaint from their customers (businesses with content to deliver) and their customer's customers (end users) is that the BitTorrent DNA client seeding/downloading in the background hurts the performance of other applications. That's unacceptable if you're trying to sell an unobtrusive alternative/complement to traditional CDN.
Yup, good ol TCP is what is causing the problem. That's because BitTorrent breaks the assumption in TCP that one application needs only one TCP stream to do its work. To solve the problem BitTorrent acquired advanced congestion control techonology and it's inventors from "Plicto." The congestion control technology lets BitTorrent work without causing crazy latency for other applications on the box. BitTorrent is the responsible party here, recognizing the need for congestion control and implementing it in their protocol. Compare that to the author of this article who saw that BT was using UDP and assumed it was a naive attempt to get around ISP blocks.
The people who work at BitTorrent are smart enough to know that you can't beat your ISP by making a new protocol. The ISP sees all and can control all, even if it may lag behind the changes. That's why BitTorrent has been working to make changes where it can make a lasting difference, in the political layer of the network.
TCP does work well, and certainly the axiom about those who don't understand TCP being condemned to reimplement it badly is a valid one. However, it is the wrong tool for many modern applications. If you're writing networking code and you find yourself fighting TCP's behavior, it's not necessarily your fault.
The developers of BitTorrent have long since passed the level of play where they're better off using TCP/IP because "well, because that's what you're supposed to use." My objection was to the naive canonization of TCP as an all-purpose protocol that's somehow magically superior to any protocol that the application can implement on its own behalf.
"Because it's the most router-friendly protocol" is also no excuse. Applications that aren't a good fit for TCP often abuse the protocol, e.g. by disabling Nagling and tinkering with other parameters in an effort to make it work more like, well, UDP.
Those developers didn't reimplement TCP badly, but they might as well have, as their efforts are likely to have the same effect.
Except that one of the cool things about UDP is that it doesn't have to get through, so your router can drop all it needs to if it starts saturating your bandwidth. UDP has no guarantee of reliability at all.
I think going to UDP would be cool for another reason: there's not all the setup and teardown for connection. If 200 people each request the same block from me in a minute, do I really want to have to go through something like 'hi can I talk to you, what port should I use, hey here it comes, do you have it, ok, I'm done talking to you go away', or should I just shovel it out? If packets get dropped en route or mangled, do they not each already have enough hashing provided by the .torrent that should indicate they're bad, and to re-request?
Get off my launchpad!
You could make the opposite argument: the cool thing about TCP is it automatically retries and resends any dropped packets, so your router can drop all TCP traffic if it needs to.
-- Ed Avis ed@membled.com
Mislabeling it is not. If you sell 1MBps with a 25GB/month cap, then you need to be advertising your "1MBps peak bandwidth, 0.01MBps constant bandwidth" service, not misleading your prospective customers.
Practically every ISP should be overselling peak bandwidth; because people don't all use it at the same time, your only choices are to let them use as much as they can (overselling) or to throttle them. But both peak and aggregate bandwidth are important; if you're not providing much of the latter you shouldn't get to imply otherwise.
If you took the current ISP business model to any other industry you'd be laughed out of town, yet they get away with it.
Cough...fractional reserve banking...cough
Set your phasers on "funky"!
Excellent analogy.
Selling a clearly marked service "
- "5mb/sec, 50gb/month"
- "1 air transfer to new york, you and 20kg of stuff, this friday at 0800"
then they oversell their capacity based on statistical analysis and when their statistical model fails, which it will always do, statistically speaking, they tell you
- "you bandwidth hog, we bill you on a backdated, horribly expensive business plan AND cut you off from now on AND never deal with you again. And if you sue, we tell everyone about your midget porn"
respective
- "We are totally sorry you cannot take this plane, take a later plane with an upgrade to business class OR take a hotel on us OR take some hundred dollar compensation"
And I was always furious about airlines doing this. Now it turns out they're actually pretty sensible about this matter and pure angels when compared to other businesses.
The real world of us grown-ups outside the Soviet Union is not about real actual costs and real actual usage, it is about contracts and contractual compensation.
Which is the reason why a bottle of Coke costs 1 dollar at the store and 20 dollar at a fancy restaurant.
Which is the reason that all the people flying with you in an airplane all paid a different price for their seat.
If you abolish that, you help people in the short run, but instantly abolish freedom of contract as the basis of any and all successful economies.
But that's too far out to mention here, because in this country, we have laws of commerce which basically just say "a contract is a contract is a contract" albeit in a hundred different clauses.
Which brings us back to your post: company A offers a contract to the general public explictly stating "x mbit/sec and no other limits for the low low price of 10 dollars per month". When General Joe Public accepts this contract, Company A and Joe are in a binding contractual obligation with each other, out of which neither can escape for non-serious reasons without serious lawful consequences.
Company A didn't sell "a reasonable and sane share of x mbit/sec, while we define what 'sane' actually means" just as Joe Public didn't pay with only a part of his 10 dollars.
If that wouldn't be the case, we would have an economy where every partner in a contract could give as much or as little as he wanted. This may work for money donations on Christmas and candy on Halloween, but is no basis for an economy. That's why we write down contracts since the Middle Ages and have contract lawyers a dime a dozen.
If you object to that, I will gladly sell you my new car for which YOU pay full retail while I deliver only a glossy brochure, three wheels, a tiny spare wheel and a bag of seat stuffing. And then terminate my contract with you telling all the world how greedy YOU are.