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BitTorrent Calls UDP Report "Utter Nonsense"
Ian Lamont writes "BitTorrent has responded to a report in the Register that suggested uTorrent's switch to UDP could cause an Internet meltdown. Marketing manager Simon Morris described the Register report as 'utter nonsense,' and said that the switch to uTP — a UDP-based implementation of the BitTorrent protocol — was intended to reduce network congestion. The original Register report was discussed enthusiastically on Slashdot this morning."
...we should have known they are full of shit.
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Detecting maximum throughput via packet dropping is really bad in high-latency links and in applications that need low latency. It is also apparently easy to implement TCP in such a way that overall transfer speed takes a nosedive when latency gets high, as evinced by Microsoft having done just that.
I don't really see how this is going to kill VoIP and online gaming. Those two services are big users of UDP, no doubt, but its not like all of a sudden the explosion of UDP requests is going to sqeeze VoIP traffic out. If anything it should encourage ISPs and providers to increase the rate of their roll out of new tech.
This move should bring into focus the last mile problem that is the real source of most of the internet connection speed debate. I don't care how the solution ends up working, but I think there needs to be a plan given that most of the plans I have heard involve several years of lead time.
Because application-specific knowledge allows easier and often better optimizations than application-generic protocols, which have to be good enough for all applications at the expense of top end performance for specific applications. Isn't it obvious?
Higher Logics: where programming meets science.
Maybe he has spent years working with the technology he is trying to one up?
This relates directly to a reply I just finished on another thread regarding whether a degree is required for success.
This Morris character may be right, he may be wrong, but you citing the education level of his rivals blows your point out of the water IMO.
I wonder if you know what you're talking about. TCP is a great general-use protocol, as is UDP. But for specific cases, like this one, developers will tend to roll their own as an extension to UDP to fit their needs.
Take any modern networked game. It will not use straight TCP, as that's stupid, nor will it simply use UDP because that doesn't work, either. TCP is fine if you're writing apps that require data to get to the other end, without regards to time taken, but if you need a happy middle-ground you need to do it yourself.
does Simon Morris think that he, single-handedly, can do better than the folks at the IETF, most of whom have PhDs in computer science?
You really have a very strange over-estimation of the value of a PhD. It doesn't mean you're a super-genius, you're smarter than everyone (or even anyone) else, or that you're always right. It simply means you've been willing to go through some schooling. That's it. Hopefully you've learned something from that education.
There's plenty of examples of non-PhD's making major contributions. The WWW was largely invented by someone with a degree in physics (undergrad I believe), with no degree in computer science. Linus Torvalds only attained a mere masters degree in Computer Science, but yet his OS seems to have become a bit more successful than quite a few other OS's written by people with more education.
AccountKiller
TCP does two things at the cost of some overhead: it ensures packets arrive in order and it ensures they arrive. While doing that, it also has to ensure that in the case of network congestion, packets are resent within reasonable time while being fair and allowing each TCP connection an equal share of the speed and bandwidth. The problems TCP solves are at the root of the success of bittorent; bittorrent is extremely good at spreading traffic in such a way that links that have those problems are avoided. It can do this since the order in which the packets arrive does not matter and in fact it does not matter whether they arrive from a certain host at all; it can simply request a lost packet from another host minutes or hours later. In the case of TCP/IP there is no provision to handle such a case; it keeps trying to get the packets at their destination in the right order as quickly as possible.
So none of the problems that TCP solves affect bittorrent and all the overhead that TCP causes, however small, serves no purpose in this case. Instead of many small TCP ACKs, resends, negotiation, and what else TCP does, bittorrent will do just fine with one status update every now and then, which it can conveniently combine with the packets that are sent the other way anyway. Therefore, IMHO, using UDP for bittorrent is fine; it will help spread bittorrent traffic even better over the fastest links while using less bytes of network traffic and it might even end up making it easier on the Internet since now bittorrent traffic no longer has to fight with other TCP connections for a fair share of the bandwidth; it can be tuned to get just a little bit less.
Of course they can fuck it up completely and fill the poor pipes of the Internet with loads of packets that never arrive, but they don't have to; it is not inherent to this solution and therefore such rumours should be classified as... FUD.
Disclaimer: I did not RTFA and now practically nothing about TCP/IP :-)
0x or or snor perron?!
There are a lot of good reasons why BitTorrent should use a UDP file transfer protocol, but I probably wouldn't put TCP's congestion control mechanism on the top of the list.
:)
If you're going to argue UDP, you might as well bring out the major benefits:
* Going to a NAK-based or hybrid NAK/ACK-based protocol which can significantly improve performance over high latency or poor connections
* Multicast - assuming anyone implements IPv6 or multicast over the internet
* NAT to NAT transfers (you can do it with TCP, but it is just harder and you generally have to build a user-space TCP stack anyway).
* Faster start time since you no longer have to do a three-phase startup and all the annoying things Microsoft does to prevent people from starting too many per second
There are plenty of UDP-based protocols with TCP-friendly congestion control mechanisms out there and plenty of research into the subject.
The biggest problems I see happening here revolve around different BitTorrent clients all reimplementing uTP and doing a poor job at it. I'd like to see a spec for uTP and a public domain implementation to help minimize the problems that could pop up.
And don't forget that those IETF PhD's couldn't design a better way to upgrade IPV4 but the incompatible and essentially non-interoperable IPV6 (please don't argue about dual stacks or something similar.)
Further, the guys at IETF are not tasked with coming up with optimal protocols for specific applications. They're not necessarily even tasked with coming up with better versions of TCP. There are tons of things they have come up with that improvements on what we use now, for that matter, that haven't been picked up by the Internet at large.
The expertise of the IETF members really has no bearing on this matter. If you were trying to actually recreate TCP (i.e., a general-purpose protocol), and the IETF said that theirs is better -- they're probably right. That's not what's going on here.
Autonomous system numbers are the perfect metric.
http://en.wikipedia.org/wiki/Autonomous_system_(Internet)
Of course it runs NetBSD. BTC: 1NT7QvbetmANwaMzhpVL6
I just got back from living in Japan not too long ago. Over there, we got 100 mbps up AND down for about ~$40/month. Near the end of my stay there, I got a letter from my ISP stating that they're going to start implementing a bandwidth cap, and that no user can upload 500gb/month, but downloading is still unlimited.
This year, I read on Slashdot that AU/KDDI is unrolling a 1gbps line for a similarly cheap price.
If you want my sympathy for ISPs in America, get back to me when I get even one tenth of the service I got in Japan. I'd like to extend a big middle finger of gratitude to all American ISPs. No one is spouting the gloom and doom over in Asia, and meanwhile, they're shooting ahead into the future of the internet. Asia's been rolling out fibre-optics, at great cost to them, but with spectacular results. Conversely, we sit on our asses and wonder how we can charge more money to more users to put them through the same amount of pipes without upgrading infrastructure.
**** you, American ISPs.
Signed,
Someone who's seen the other side of the world, and it was better.
This reminds me of grc.com's dire warnings that Windows XP's "raw sockets" would cause chaos on the Internet. Total and utter bunk. But I guess that's what you should expect from the Register.
XML is like violence. If it doesn't solve the problem, use more.