Testing µTP – is µTP actually faster than regular BitTorrent?

Recent coverage of uTP on the popular Torrentfreak blog yielded some interesting feedback in the comments section.

There are a couple of misconceptions that I’d like to address here:

First is the idea that we designed uTP *for* the ISPs. It was not.

While we think there are substantial advantages for ISPs in the broad adoption of uTP, the protocol was actually built from the start as a way to help consumers themselves. The fact remains that when using TCP, a poorly tuned BitTorrent client may well result in an internet connection that habitually gets congested and then drops packets, then recovers and repeats the process. This is not good for anyone.

The second misconception is that uTP will somehow slow uTorrent down. This is also not true. It will certainly result in less headaches for everyone and it may even speed things up.

Our design objectives were always to leave transfer rates unchanged, and we’re still confident this is achieveable. The fact that you don’t have to manually “manage” your client or limit it to some arbitrary % of your connection should mean that in practice it will be reliably faster. What’s more, we may actually be able to make it go faster than an unlimited TCP BitTorrent client. The way to picture this is to consider cars on a highway: you can only drive at 90 mph if there’s not much other traffic. But if there’s a lot of traffic then quickly the whole system will snarl up. uTP is designed to make clients transfer at an optimal speed *without* causing a snarl up. The thrill of speeding along at 90 mph is rather lost if you keep having to slow to a crawl until things recover. By avoiding this “stop/start” we felt that uTP *should* make things go faster overall.

Early evidence is starting to come out now from researchers at the University of Washington who are performing some independent tests on uTP performance. (These results are NOT conclusive at this point, but the early indications are quite good…)

From the first graph below you can see the interaction of uTP traffic (green) with some other application competing to use the connection (red). As expected, the uTP traffic backs off immediately and is replaced by traffic from the competing application – upon completion of the competing transfer, the uTP BitTorrent traffic quickly resumes. The blue data points represent the uTP traffic holding steady against the (right vertical axis) target delay of 100ms (I’d note this is vastly lower than anything achievable with TCP BitTorrent transfers).

The uTP controller is clearly doing its job, spotting a different application trying to use bandwidth and getting out of the way, only to recover just a fast.


But in many ways the more important graphs are the following…. These show you that uTP BitTorrent is just as fast as best-case TCP BitTorrent, and may even be faster…

noUTP withUTP

Now one likely explanation for this is that the uTP overhead (a few % of the traffic which is not actual content) is included, but the TCP measurement excludes it. If this were true then probably uTP and TCP are almost identical.

But if we find that uTP traffic is indeed faster than TCP BitTorrent traffic, there are a couple of reasons why this slightly surprising conclusion might indeed be true –

Either the stop-start nature of TCP-based BitTorrent creates inefficiencies that are being optimized away using uTP.

Or else there were ISP network management measures in place which were discriminating against TCP-based BitTorrent.

Or possibly the UDP NAT-traversal techniques introduced along with uTP were resulting in far more good peers with uTP.

Or possibly something else?

Whatever the reason, this is early evidence that uTP is an even bigger win for consumers than anticipated, as well as being a positive contribution to ISPs.

Much more work remains to be done, but this is exactly the type of result we’re hoping to see more of.


45 Responses to “Testing µTP – is µTP actually faster than regular BitTorrent?”

  1. Yelp

    Any updates on this report? People are waiting to hear how uTP affects seeding rates on slower connections now since its being blocked from various sites due to this.

  2. Max Power

    I understand UW Seattle EE may be testing the ins and outs of uTP — but testing uTP just inside the US is less than adequate in the long run.

    You must consider the undersea cables, and the affects of multiple cable hops. uTP must work for paths with 31 hops or greater with the same performance as it does for 7-10 hops more typical in the EU or USA.

    Suggested paths to try (and Universities)
    Cambridge UK –> Otago Uni, NZ
    Curtan Uni, WA-AU –> UW Seattle US
    etc …

  3. psuedonymous

    PROTIP: when displaying graphs intended for comparison, the axes (and especially, the y axis) must use the same scale.

  4. dñåp

    MARCH 25, 2010

    Apparently, the jury’s IN on uTP.
    Certain PRIVATE TRACKERS have just recently dropped support for any version of uTorrent that uses uTP – so you’ll have to downgrade to anything below 2.0 to connect.

    [quote from ILoveTorrents]:

    “utorrent 2. has been out right banned, because it slows down swarms by favouring mainly other uTP clients, and as utorrent 2. is the only one that impliments uTP, it is mainly ignoring others in the swarm”

    Personally,after testing all the uTorrent BETA version (as they were released)I have seen no noticeable improvements using uTP. (outside of the occasional convenience of udp (yes, “User Datagram Protocol” – a feature that uTorrent claimed that they would NEVER include…)

    Unless you enjoy having your displayed columns reset to “default” EVERY TIME YOU START THE PROGRAM, you should AVOID THIS ONE AT ALL COSTS! (Actually, that was just what I needed to decide to downgrade below 2.0)
    DON’T GET ME WRONG, HERE – I’VE REALLY ENJOYED uTORRENT FOR YEARS….unfortunately, they just can’t seem to leave a good thing alone.
    Any further “Improvements” might be all the convincing I’ll need to switch to a different client altogether.

    • Simon Morris

      Well I’m sorry these quotes are so negative on all our hard work.
      Its true that there are some minor issues that we have been made aware of and we are working through. We’d like uTorrent to work well for everyone, and we’ll continue to tweak uTP until we get there. I’m confident that the people who have found fault with the new uTP protocol will ultimately see changes that address their concerns.
      Here’s how I personally think about this: uTP is a critical project to make BitTorrent traffic fit better with the internet at large – both for consumers and for network operators. The protocol has been so ridiculously successful that it has attracted serious attention of the people who run the networks. If we don’t address this then the protocol doesn’t have a future on the internet in the long term. You can believe what you like about protocol obfuscation, encryption, and the like, but playing a game of “dare” with the people who own the pipes is ultimately a stupid and naive strategy. uTP is an effort at resolving a major part of the complaint. We have been and continue to be very open about the technology and encourage others to implement it. Implementing new technology is sometimes a hard path and there are lessons to learn. We take user feedback seriously and we are learning – I hope we can ultimately achieve the goals of uTP for the benefit of BitTorrent users everywhere. I hope you and other stakeholders can appreciate these issues as “teething troubles” – something we’ll work through – and not continue to claim that “the jury is in”.

      • dñåp

        Thanks for your prompt reply to my comment – it’s refreshing to actually have real people on “the other end”.

        Let me also say that as negative as my comment sounds, I’m still hanging in there with you guys, since I do feel that your service is the best out there. I am somewhat frustrated with ILT’s ban, since I do use their tracking service.

        In all fairness, my “Jury’s In” comment was somewhat premature – I’ll reserve opinion on that based on other private trackers actions.
        As for the BETA stuff, well, that’s what BETAs are for – testing. Nobody forced that one on me, so in all fairness, I can’t really hold that against you.

        I CAN complain, though.
        At least you guys are listening!
        Thanks again!

    • Kirn Gill


      Well, the idea here is that it IS broke, and that just because something manages to actually complete a task, does not mean it is free of defect.

      So yes, please fix BitTorrent with µTP. I, for one, would like to use my VoIP-based phone service without having to shut off my torrents first.

  5. Angel Bravo

    utp sucks
    since i started using utorrent 2.0 my speed dropped to half !
    i disabled utp in options so i got my speed back, but i noticed that the number of peers dropped (connected only to peers who doesn’t use utp) so what am i gonna do when all peers start using utp ?
    utp is a disaster

    • Simon Morris

      hi Angel – sorry you’re having some issues – you should try downloading the v2.01 beta which should go stable in the next few days (its available here as a release candidate) – there are occasional (very occasional) problems that we’re fixing, and hopefully your case will be included – there’s no reason to believe what you see is anything but a temporary bug.

  6. hackenslay

    I dl’ed the new client and never would have noticed a difference if I hadn’t come here to do some light reading. Thanks guys/gals…I agree that thumbing your nose at authority is fun but counterproductive. The fewer complaints about bandwidth-hogging apps the better, and the more likely utorrent is to maintain its’ operations.

    ps-I did notice that my internet radio doesn’t get choked off by utorrent anymore… a very good thing.

  7. Blake

    I’ve been on µTorrent for yonks and frankly µTP delivers. Torrents are all about profile. Kudos to the team: took brains to implement a hard-coded fair use policy with the benefit of better bandwidth sharing for my on-line apps. It’s ended connection crawl rot on my box. Better to be a hare in a tortoise hat, faster in the long run and the pipe owners likely whine less to gov’s.

  8. RudeBoySes

    I have been testing uTorrent 2.0 Beta since the first initial release .. my speed has has increased .. now im not sure if it’s due to my ISP or because of uTorrent..

    however.. i’d like to point out that uTorrent does not determine your speed.. your ISP does..

    if you’re running a 56K .. you can’t expect uTorrent to magically turn it into a T1 line ..

    Quite honestly.. i haven’t noticed anything negative.. considering uTorrent is free .. i have nothing but gratitude ..

  9. Morrigan

    Frankly so far from what i’ve seen uTP delivers i can now torrent while i game without fear of it choking my connection keep it up people. awesome work

  10. Richard

    Ey dudes keep up the uTP its great. got 10 mbits up and down (20 mbits+) on a internet linje that i shoud only get 256 kbits.

    love it uTP + enkryption 🙂 thank you 😀

    love you guys.

  11. antiutp

    what a bunch of lies.
    uTP DOES slow down uTorrent.
    Remove this feature, or at least give the end-user the possiblity to switch it off!!!!
    For those who use uTorrent or any bittorrent clients since the beginning, it is a great step back.
    We know our own device possibilities, our own connection capacity. So, being taken for noobs and our downloads being slowed down cause we are upping 10ko instead of 12ko is an insult.
    Keep this if you want but give us the possiblity to switch it OFF!!!!!!!!!!!!!!!!!!

  12. Simon Morris

    Thanks for your posts “antiutp” – sorry you’re having some trouble. Your post didn’t show up as this is a moderated blog and you posted it at 2am our time.
    In spite of your remarks, the data here is not “a bunch of lies”. Having said that, we do hear of isolated cases where uTP has caused problems and we’re continuously working to fix them.
    Whats more, if you’re having trouble and want to turn uTP off, you simply need to ask someone knowledgeable (like in the uTorrent forums).
    The answer is go to Preferences > Advanced and set the value for bt.transp_disposition equal to 5.
    The last thing we want to do is insult you or any of our users. Perhaps the least we can ask in return is that you treat us with a tiny bit of respect.

  13. dñåp

    The default value for bt.transp_disposition is 31.
    Unchecking “Enable bandwidth management” (Preferences > BitTorrent) will do the same thing – set the value for bt.transp_disposition equal to 5.
    UP UNTIL TODAY…and the release of uTorrent 2.0.2
    The new version sets bt.transp_disposition to 21 instead of 5 when you uncheck “Enable bandwidth management”

    So it would seem that the new version is gonna try to manage your bandwidth regardless of how you set it.

    @Simon Morris: Thanks for the info on turning uTP off.
    Maybe you could explain just what “bttrans_disposition is, and what setting it to 5, 21, or 31 actually does. What happens if you set it to Zero?

  14. Anon

    I’d like to know what’s going on as well.
    My dl speed is more than halved….

  15. Gustavo

    Yes, I quote user Yelp and reinforce his asking about more conclusive reports.
    Are there any updates on new tests? Are there new tests being conducted?
    So far I’m pretty satisfied with all this new protocol approach, and I’m even beginning to make my own advertisment here on my country on this new feature, and the benefits it seems to be fostering to everyone. So far, I’m rejecting all that talk that says “…I will set beack to my old client”, or “…why have you changed something that was working”.
    But, so far, it seems that conclusiveness is tending more to the critics side – which are performing aparently well structured tests by their own – than to your – our – own side.

    We’re eager to, at least, be given some updates, even if not conclusive, as to show how things are going, etc, etc.

  16. JimShew

    While uTP may work at higher speeds under ideal conditions, at the low-end extreme (bitTorrent download of a single multi-megabyte file over a dialup connection (Ubuntu linux install CD)) its implementation in 2.0.1 seems to slow the already glacial 3.3Kbyte/sec connection. uTorrent’s log shows it has had to transmit 18 hang reports over the past 5 hours.

  17. Zeratul678

    Well, I read some of the comments above, and, not all people can love something easily. There will be haters in this world. No matter how nice, caring, respectful you are towards them or other people.

    On the subject, I think uTP is not much of a bother, but, since the internet is always busy, the speeds are mostly slow. At night is a different story though, it’s always slower at night right? For one day I average a dl total of around 2.4GB. I think utp is a good thing in the long run, but I’m still having some doubts about how smart the system is and can be. Who knows, this could be a revelation or revolution. I’m not going to say that utp shouldn’t exist because maybe in the future I’d have to swallow my pride because I insulted the uTP system. Good job on the utp thingy guys.

  18. rdc85

    I notice my torrent speed drop a lot since using 2.0.1, but in other hand it speed up my game connection (usually i need to limit the torrent to keep the game smooth). It’s double edge sword, it will be good idea to have an option to choose using uTP or not so when we playing games and other we use uTP, when we go to sleep we switch off the uTP.

    The speed seems to improve a bit in 2.0.2, well keep waiting for next improvement.

    • Winjay

      I totally agree with your idea. There should be a big button to switch it on and off easily.

  19. Gustavo

    rdc85, I assume you’re talking about uTorrent client.
    What you want it’s easy to do, although I’d rather like you to follow Rafi’s guidelines. Just go to uTorrent Forum, then Announcments, and in the post that announces the latest version, look for Rafi – I think he’s the one that posted the announcement – then take a look if not at the announcement itself, at his signature’s link. He has the guidelines to turn uTP off. If you’re not confident about that, just add a post with what you want and they surely help you. I’m a newbie in this, and I sometimes get hellp from them.

  20. John

    The software would be improved if you allow users to turn off this “feature” in a convenient way…ie…not having to understand or anticipate a changing and complex bit-mapping field. The hesitation in doing so raises suspicion. Guys, its just a client, not a religion. Just give people the choice and don’t punish them if they don’t choose your predetermined protocol grail. Otherwise I have to move onto the next client…

    • Simon Morris

      This is done – you can switch it off by going to Options > Preferences > BitTorrent and deselecting “Enable bandwidth management”

  21. Queequeg

    A quick question. It appears some users are noticing a speed difference when using uTP. (Personally I have noticed no difference). Does uTP depend on having the majority of BT traffic in this new protocol? IE, will speeds increase once all other clients (or at least the majority of them) swith to uTP as well? (From the description above, it seems like it would help, and so it should only get faster as more people/clients adapt.)

  22. Eduard

    µTP can’t speed up your torrent-client. It’s impossible by design. 🙂
    If it don’t improves your upload speeds, how this can improve others downloads?

    Yes, µTP can improve your bandwidth control, so other application, that require own traffic, can run smoother, but you NEVER get your bittorrent speeds better with it. Noway.

    So, placing words “µTP” and “speed” in one sentence is bad idea.

    To get things clear, I wrote about this article, not about µTorrent team work overall. But I’m very sorry about µTP creation. µTP is designed to create work for µTorrent team. =:} If you need SPEED, you DON’T need µTP. Definitely.

    P.S.: µTorrent 1.7.5 is greatest bittorrent client ever!

    • Simon Morris

      hi Eduard – as a matter of fact we’d disagree with you on this one – uTP is designed to increase the AVERAGE speed at which you download by eliminating the crazy stop-start that happens when networks which rely on TCP get congested and then un-congested. That is the *design* at least. As we are finding out, the internet is a very diverse place and there are certainly edge cases where TCP works faster. We’re making changes to accommodate more and more of those edge cases. If you want to test the difference then its easy enough to switch uTP off – just go to the BitTorrent preferences and deselect the “Enable bandwidth management” checkbox.
      Better still, if you discover some issue then please post details about it in the forums on uTorrent at http://forum.utorrent.com so we can improve things for you.

  23. Eagle

    I was hesitant to update from uTorrent 1.8.5 while the 2.x was still freshly released to avoid the bugs. Now that I have updated uTP has noticeably improved my peer connectivity.

    However, it was noticeably slower in its default setting and did more than halve my average speed. I changed bt.transp_disposition to 5 as suggested above and my download/upload speed went back to normal but with the increased connectivity. Seems uTP doesn’t handle my slow mobile connection at 28 kB/s down and 11 kB/s up with average 250 ms ping.

    Overall I would say I am impressed and optimistic to the new protocol.

  24. Skimoo

    I personally did not have any hesitation to install V 2.0.3 ( had not updated in a while ) especially after reading about uTP ;
    How ever after installing I suffered a dramatic cut down in my DL speed.

    I have read through the previous comments to see if any one had a similar problem, I then turned of uTP to see if I had any improvement.

    How ever the speed did not change. I am from NZ and I can imagine that could be a specific reason but im talking about a 75kb/s drop on a already ridiculously slow DL rate. I was just wondering if anyone had any advice for me?
    It would be gladly appreciated seeing as I don’t want to be slower than I already was.

  25. Chris

    I just recently switched to trying uTP in a Linux-based Torrent program. Interestingly, a torrent I had running at the time that was extremely slow and had found very few seeders suddenly found MANY seeders after switching to uTP. The conclusion I gather from this is that at least some torrent programs are using the uTP protocol exclusively.

    Second, I for one really appreciate uTP’s ability to back off when other programs are trying to use the network… as it means I don’t see lots of lag or have other household members complaining that “the internet is really slow”.

    Third, from an engineering perspective having Torrents work over connectionless UDP makes a whole lot of sense for both throughput and connection latency reasons.

    Bottom line is that uTP is an all-around win, IMHO.

  26. Erv

    About speed, this last download my top speed was988kb/s(not avg.)I got 18gigs overnite.
    that’s not bad.
    Although it may have alot to do with the site.
    I don’t know, I’m a novice(begining to learn).

  27. ether

    Hi. Myself being not the most Comp’ Tech’ literate individual I have a question RE: the uTP vs. TCP. What it is I have to ask may have already been answered (in one way or another) in the above article and/or the comments although it is one of the (above mentioned) comments in particular which has served as (an extra helping of) confusion for myself (to an already ‘it’s all greek to me’ type of scenario, as long as it’s downloadable and only requires a few basic modifications to get it running i.e. uTorrent, I can usually figure it out over time by trial and error but otherwise …). Having said that I am rather intrigued by what I’ve read thus far concerning uTP vs. TCP and My Question relates to the following: I am currently running uTorrent 2.2.1 and read else where that, “µTP is a new lightweight BitTorrent protocol used by µTorrent starting in µTorrent version 2.0”, although above I noted the following, “…. so you’ll have to downgrade to anything below 2.0 to connect”. So I guess what I’m trying to ask is 1. Does my version 2.2.1 already contain this uTP concept (by default, and therefore I need not do anything)? 2. If ‘No’, can the uTP be applied to version 2.2.1 (and if ‘Yes’, How? and if ‘No’, which version do you recommend). While I have you on the line (so to speak) one more question (or 2) if I may, 1. I am connected via Phone Line (Broadcom NetXtreme Gigabit Ethernet, I am unsure of the specs’ to share concerning such so I include this (above) in hopes that it relates some nec’ info’ to you) and when downloading a (1) Torrent (Movie) my avg’ speed is apprx’ between 110-128 kB/s (unless during the wknd and prime-time then drastically lower). Is this a respectable speed? My question 2. relates to the previous question by way of my stated avg’ speed when downloading, however it’s specific to the fact that no matter if I’m downloading 1 Torrent or 2 or 3 at a time my ‘Total’ Speed (kB/s) will never exceed this (max’) avg’ of 110-128kB/s (and the same tends to go if downloading only 1 and the upload is reading (say) 50kB/s, such would then limit my dwnload spd to (around) 70kB/s for again a avg’ total overall kB/s of 120ish (now I know I can limit the upload and thus remedy that certain situation in that manner but I don’t like limiting peoples ‘efficiency’ (unless such is generally nec’ and widely employed and I’m just not aware of these types of ‘mannerisms’)) and also that remedy does not apply to my scenerio including multi’ simultaneous downloads, also I have my Preferences Max’ Download (and Upload) set at ‘0’ aka Unlimited). Now myself not being overly fluent in this type of stuff I don’t know if my numbers are typical (in which case I am perfectly happy with them) or if they are dreadful and you may be able/willing to kindly direct me to 1 or 2 remedial approaches towards bettering (is that a word?) my efficiency. If by chance anyone has hung in long enough to get to this point in my novel I truly do appreciate your time and consideration and would be most grateful for any advise that may come my way. If the length of this is viewed as unacceptable I do apologize (another lesson learned) and, should you be willing to speak to that which I have enquired about albeit without breaching the ‘comment length boundaries’ (as I may have done), please feel free to email me at ether04@hotmail.com
    Again, Thank You Kindly!!!

  28. Blackskunk

    I have been using uTP without knowing it and have not noticed any difference either way as all files download at wildly different rates for various reasons anyway.
    Whilst I cannot completely understand all of the tech stuff, the broad concept of uTP sounds good and makes sense. A bit like slowing cars on a motorway where traffic ahead is dense to prevent being stuck in a traffic jam? Would you agree Simon?
    I am a great fan of uTorrent and have been using this free software for many years. It is a shame when people put a lot of effort into trying to improve stuff for others and get rude comments on forums like this. Unfortunately this is all part of life.
    Constructive criticism should surely be welcomed by all, but there is no need to be rude.
    I think you guys at uTorrent are doing a great job, keep it up.


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