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Networking The Internet

Ask Slashdot: How Can I Prove My ISP Slows Certain Traffic? 203

Long-time Slashdot reader GerryGilmore is "a basically pretty knowledgeable Linux guy totally comfortable with the command line." But unfortunately, he lives in north Georgia, "where we have a monopoly ISP provider...whose service overall could charitably be described as iffy." Sometimes, I have noticed that certain services like Netflix and/or HBONow will be ridiculously slow, but -- when I run an internet speed test from my Linux laptop -- the basic throughput is what it's supposed to be for my DSL service. That is, about 3Mbps due to my distance from the nearest CO. Other basic web browsing seems to be fine... I don't know enough about network tracing to be able to identify where/why such severe slowdowns in certain circumstances are occurring.
Slashdot reader darkharlequin has also noticed a speed decrease on Comcast "that magickally resolves when I run internet speed tests." But if the original submitter's ultimate goal is delivering evidence to his local legislators so they can pressure on his ISP -- what evidence is there? Leave your best answers in the comments. How can he prove his ISP is slowing certain traffic?
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Ask Slashdot: How Can I Prove My ISP Slows Certain Traffic?

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  • by locopuyo ( 1433631 ) on Sunday March 18, 2018 @03:39AM (#56278627) Homepage
    They might not be slowing down specific traffic but instead just have a poor connection to those popular services and it gets saturated.
    • Alternatively: (Score:5, Informative)

      by Anonymous Coward on Sunday March 18, 2018 @03:56AM (#56278655)

      Find a free vpn service, like vpngate, and run your connection over to a site (other than netflix, due to geoblocking) that normally runs slow for you. If your speed sees an increase, then yes they are throttling traffic to certain websites. If your speed is the same or less then no your connection to the outside world is just shitty. That is the #1 benefit to vpns for the consumer imho. Unless it is a specific service they are degrading they can't tell who your vpn connects to, and either they throttle all vpns, which commercial users would frown upon, or they throttle none of them beyond regular bandwidth limits and you can find out if that is where the problem lies.

      • Re: Alternatively: (Score:5, Informative)

        by saloomy ( 2817221 ) on Sunday March 18, 2018 @04:09AM (#56278673)

        Not necessarily. The internet is comprised of a bunch of networks. If you are getting slow service to Netflix, it may be that you are traversing a saturated peer (maybe your ISP's peer, maybe their upstream provider's peer).

        When you use a VPN, you are routing to a different site, which might have no saturated peers in the chain. Then from that site, you have a decent link to a Netflix node.

        You are routing around using the VPN.

        Also, 3mbps isn't great for streaming. When you say it's slow to Netflix but fast for sites, consider the volume of traffic. Netflix needs 5mbps for HD content, so you probably do t have a slow connection to one site, just in general.

        • Re: Alternatively: (Score:5, Interesting)

          by silas_moeckel ( 234313 ) <{moc.proc-cnimsd} {ta} {salis}> on Sunday March 18, 2018 @08:57AM (#56279157) Homepage

          If your ISP has a constantly saturated peer that is in effect throttling. We have seen ISP's use BGP traffic engineering to try and push all netflix traffic through a specific peer and then let it saturate the links as a bargaining tool. This should not be allowed. Realy any link that's saturated anywhere inside an ISP or with peers and transit providers should not be allowed in the long term.

        • by skids ( 119237 )


          The proper tool to try to figure out where packets are being dropped or delayed is called "paratrace"

          You kind of need to know what you are doing to use it properly... you have to find the connection that is being slowed and jump on it.

          Also, and this goes for traceroute, too, if a single transit node has high loss or delay, but the nodes beyond it do not, then that node should not be blamed... returning packets due to TTL exhaustion may be CPU-bound or control-plane-policed on a transit node, which is no

        • by Kludge ( 13653 )

          When you use a VPN, you are routing to a different site, which might have no saturated peers in the chain.

          If your VPN can take a faster route than your Netflix, your ISP could choose, if they wanted to, to route your Netflix that way too. By choosing not to, they are in effect throttling your internet.

          • No. BGP doesn't work that way. It is not a load balancing routing engine. It picks the shortest path first, and sends traffic that way. Also, different paths that he may be traversing might be significantly less congested but much smaller. Sending the traffic that way could overwhelm the other peer.

      • That doesn't prove it at all, by using a VPN you are going via different routes, possibly routes that are not as congested so you can get faster or slower speeds naturally through such a test. The reality is though services like Netflix et al do slow down considerably during peak viewing times as all ISP's have high congestion ratios, some worse than others.
        • by dwywit ( 1109409 )

          That's a big issue with the National Slowband Network in Oz. The resellers aren't buying enough capacity from NBN Co - so everyone experiences "buffering" from 5 - 10pm (or thereabouts).

          I'm not going to sign an NBN contract that doesn't guarantee a minimum speed of at least 25MBit/s down - wish me luck.

          There's a 5G network being rolled out on the Gold Coast to support the imminent Commonwealth Games - let's see what happens afterwards, shall we? After people have been been able to watch sports in 4K (and lo

          • Re:Alternatively: (Score:4, Insightful)

            by ColaMan ( 37550 ) on Sunday March 18, 2018 @05:54AM (#56278857) Journal

            It's not "buffering" or a "slowdown", it's advertised as "evening speeds".

            As if it's a perfectly natural thing to experience congestion during the evening.

          • if you don't want the slowdowns or at least for them to not be as bad then go with one of the providers that promises much lower contention ratios like Aussie Broadband. though the reality is the only way to absolutely guarantee you have 100% bandwidth is to buy a dedicated bandwidth, but then you better add at least another zero to your monthly bill.
            • Solution is:

              Rent the CD with the movie you want to see from Netflix.

              Use the program 123 Copy DVD Platinum to rip it to your disk.

              Watch the movie from your disk. No buffering.


          • That's not true for all ISPs.

            Avoid anyone selling "unlimited internet", that'll never work with the CVC costs and the leaches it attracts.

            I'm on a $69 for 1TB a month on a 100Mbps plan and always get over 80Mbps.

            Shop around and ignore the big guys, they're all shit.

            Go to whirlpool and checkout Telecube and then thank me later.

            • Re: (Score:3, Interesting)

              by Anonymous Coward
              I'm paying $50/m for a 150/150 dedicated fiber with dedicated bandwidth in the USA, at my home. I get 150/150 to nearly every datacenter in the world at every time of the day. They literally advertise ~"We're not like that other ISP. We sell *dedicated bandwidth. You will never experience any slow downs...*Dedicated through out network and to our transit provider".

              When I first got services from them, I talked to the manager of network operations, asked them how they could afford dedicated bandwidth. He s
            • by dryeo ( 100693 )

              Not everyone lives in a small highly populated country with actual choices for an ISP.

      • by pnutjam ( 523990 )
        You can also try a speed test specific to the service you want to use.
        Netflix has one: []
      • by lsllll ( 830002 )

        Find a free vpn service, like vpngate, and run your connection over to a site (other than netflix, due to geoblocking) that normally runs slow for you. If your speed sees an increase, then yes they are throttling traffic to certain websites. If your speed is the same or less then no your connection to the outside world is just shitty. That is the #1 benefit to vpns for the consumer imho. Unless it is a specific service they are degrading they can't tell who your vpn connects to, and either they throttle all

    • by baomike ( 143457 )

      I think you have that right. I try to download files from GB prior to 1800 PDT as after that time the rate drops like a rock. What takes 5 minutes at 1600 takes 30-60 minutes at 2000. These are not netflix files but it would seem that in the evening netflixs flood the system.

    • BS (Score:5, Insightful)

      by PortHaven ( 242123 ) on Monday March 19, 2018 @08:15AM (#56282827) Homepage

      Comcast deliberately and specifically used to slow down Netflix traffic. Prior to Netflix paying them for peering.

      I had Comcast's 25mbps speed package, but couldn't stream Super or 3D content. Bandwith was too slow. Dropped my service down to 3mbps. Netflix and Comcast signed peering agreement. Suddenly, the very next day my 3mbps connection was fast enough to stream 3D content from Netflix.

      Ya....don't give me the congestion BS. The telcos very knowingly throttle certain content.

  • You can't really (Score:4, Informative)

    by Njovich ( 553857 ) on Sunday March 18, 2018 @03:46AM (#56278635)

    Traffic slowed by your ISP, and traffic slowed further down the chain - for instance by poor peering - are indistinguishable. With some help from hops further along like Netflix (or within the ISP) you may be able to pinpoint the exact problem. However, given that so many providers are capable of routing Netflix at acceptable speeds it also doesn't matter, it's obviously your ISP's responsibility.

    • he can try fiddling with ttl values and send duplicate packets and measure their roundtrip.
      not easy, i know
    • you can... (Score:4, Informative)

      by johnjones ( 14274 ) on Sunday March 18, 2018 @04:12AM (#56278677) Homepage Journal

      its not that hard

      but you have to have at least two connections to compare the traffic

      a study that was funded by a USA national science award does exactly this :

      simply download a app and run it []

      you can thank me on twitter if you like []

      • I don't have a Twitter machine so I am thanking you here instead :)

    • by Greyfox ( 87712 )
      Back in the day you'd fire up a tool like traceroute (or mtr) and see which hops are causing the problem. For me, it was always a sprint border router in Atlanta dropping all my packets on the floor. Seems like a lot of Linux distributions don't bundle traceroute by default anymore. In these days of generally-installing-everything-properly ubuntu (et al) distributions, you don't really need to be a sysadmin with a lot of networking know-how to run a networked Linux machine. Just get the wifi-enabled cable-m
  • by Anonymous Coward

    Until the government ensures a quality service on ISPs to make them similar to land-line phones (common-carrier), it doesn't really matter if you complain about small things you find. I have had VOIP blocked by the ISP due to their competing service, and have had speed issues that looked better with the speed test, but it really can't get resolved until the government cares about the Internet as critical infrastructure which can easily damage the economy.

  • wireline might be a problem. Before the ISP side of the network.
    Streaming services will often consider a users connection and change their streaming service to what they think will offer the best experience.

    Long term support any innovative new community broadband network and see how the different networks do networking?
    Freedom of choice.
    Support a better new network.
  • (Score:5, Informative)

    by Anonymous Coward on Sunday March 18, 2018 @03:57AM (#56278657)

    This site uses the same servers as the Netflix streaming service so it should be a clear indicator. You should note though that 3Mbps isnâ(TM)t very fast when it comes to playing streaming video. An HD stream from Netflix can easily hit 7 or 8 Mbps.

    • (Score:5, Informative)

      by Sarten-X ( 1102295 ) on Sunday March 18, 2018 @04:13AM (#56278679) Homepage

      It's disappointing that this is currently scored 0. This is the right answer for this scenario.

      With strong Net Neutrality laws, there are limits to how sophisticated ISP throttling can be and still pretend to be legitimate. With that essentially eliminated now, the only meaningful test is to use actual traffic. Netflix has preempted this need for their own services by creating [] to look identical, going to Netflix servers over the same ports and protocols as normal Netflix traffic. It will be subject to the same throttling, and thus allows you to measure the speed you get when working with Netflix.

      I'd love to see other services hosting similar tools, but for now Netflix is the only major company I know of offering their own user-accessible performance test.

      • The problem with that is that by going over the same network and peering links all you will see is your actual current speed with no indication about whether you are being slowed down by contention/congestion or through throttling.
        • Both are gamed by the ISP and have the same result. It doesn't really empower me one way or the other to know the difference

          • The question asked was "how can I prove my ISP Slows certain traffic", the site mentioned does not provide a solution the ability to discern that.
            • Both are the ISP slowing traffic. Intentional sabotage of peering link capacity is no different effectively than throttling.

      • Indeed. My ISP is pretty good (I'm the one throttling Netflix traffic here at my house... wife and 3 kids eat up a lot of bandwidth and I need some reserved for me to do homework) so it hasn't been a concern for me but I've wondered why there haven't been content provider supplied speed tests. Of course, I didn't know about either...

      • It's disappointing that this is currently scored 0.

        It's disappointing that you think 16 minutes (including the time it took for you to type your post) is too long for an anonymous post to get modded up. I'm rather glad that AC posts don't just start at Score:2 for no good reason. The post in question is proof that the moderation system is working correctly and effectively, even if not instantly.

        • Eh... groupthink and vitriolic anti-corporate shitposts get bumped up in far less than 16 minutes, but I digress.

          When a good comment that perfectly responds to the topic at hand (and with good information) sits at 0 because it happened to come from someone unregistered, what's really disappointing to me is that there is no good solution. Heuristics to guess an expected score can be gamed. Tracking users without accounts is a privacy minefield. Assuming an initial score and letting the mods do their thing le

    • (Score:5, Informative)

      by Athanasius ( 306480 ) <(gro.yggim) (ta) (todhsals)> on Sunday March 18, 2018 @07:16AM (#56278969) Homepage

      I was going to post if no-one else had.

      There's also a list of other tests on []

    • All the major streaming services offer their own speedtest. There's an Apple App (yes, it was approved. It was only delayed while apple confirmed it wasn't snakeoil) that will check all the video services speedtest sites. I don't know if it's open source, but there was a slashdot article on it a while ago. Or you can build your own script.

    • Except if I was an ISP and we throttled Netflix, I'd specifically whitelist (and other speed tests). I wouldn't use this as any sort of proof that throttling is or is not happening.
      • by suutar ( 1860506 )

        you mean you'd specifically throttle, right? Otherwise you're just making it really blatant that you're treating netflix traffic differently...

        • No, I'd let those speedtests run at full speed.

          The implication is that is owned by Netflix, and if that operates at full speed, Netflix obviously operates at full speed. If results are consistently lower than others, THAT would imply that Netflix traffic is being treated differently. And this way I, as an asshole ISP, could say " is run by Netflix, if it's showing you good speed, and videos aren't playing well, then it must be an issue with Netflix's servers"

  • by Anonymous Coward

    1. Get job working for ISP
    2. Slow certain traffic
    3. Film yourself
    4. Post video to youtube

  • Many ISPs large and small explicitly add rules prioritizing speed test servers over normal traffic. To this day it baffles me why ISPs are getting away not only with blatant violation of NN by prioritizing specific destinations over others but with what is essentially intentionally misleading their customers with bogus results as a consequence of prioritizing speed tests. The trick to obtain meaningful results is in finding much less known speed test servers or just downloading large files from a sampling

    • Far be it from me to defend a carrier or telco, but you're not being realistic.

      ISPs have routes to other peers. Inside their own realm, they may or may not have links or even hosted content distribution networks to ease the traffic on their core routers. Netflix, along with Akamai and plentiful others allow peering agreements to boost the QoS of their delivery to end nodes.

      This in turn, is a bit different than how LTE carriers deliver their own feeds. Some people NEVER watch a movie on their phone, and othe

    • by pnutjam ( 523990 )
      If you have access to a server elsewhere, you can use iperf []. That's usually my gold standard for testing links.
  • Streaming is a complex game and it can get disrupted in many ways. Packet loss, jitter, reordering, buffer-bloat, brief interruptions on traffic spikes, etc. all things that are no so bad with TCP can really, really mess up streaming. My guess would be that the streaming services all use a very similar set of parameters for their protocols that in general work reasonably, but with your connection does not work well at all. The solution to that would ordinarily be to just download the files and then play loc

  • by Ambrose Carracho ( 3020985 ) on Sunday March 18, 2018 @04:31AM (#56278707)
    Many devices allow you to check your connection speed within the Netflix app. (I would presume HBONow offers a similar utility.) The Netflix Page explaining how to do this is here: []. On the same Netflix page are their internet download speed recommendations for playing TV shows and movies: 0.5 Megabits per second - Required broadband connection speed 1.5 Megabits per second - Recommended broadband connection speed 3.0 Megabits per second - Recommended for SD quality 5.0 Megabits per second - Recommended for HD quality 25 Megabits per second - Recommended for Ultra HD quality Remember that these figures are per stream, so concurrent streaming to multiple devices is bandwidth additive.
    • by dargaud ( 518470 )
      Also, do some speed tests. Then load up a VPN (one you pay for, not a free one), and do the test again. If the speed jumps up, something fucky's definitely afoot.
  • I'm not an expert on these things, but maybe do it from the outside? Set up an internet facing server on your network and then push and pull data using a known honest provider.

  • by jrumney ( 197329 ) on Sunday March 18, 2018 @05:41AM (#56278813)
    Can one of the editors explain why a high 6 digit Slashdot reader qualifies for the honorific title "long term", but a low 4 digit Slashdot reader does not?

    Has darkharlequin done something to displease the editors?

  • Matt's TraceRoute (Score:5, Informative)

    by jrumney ( 197329 ) on Sunday March 18, 2018 @05:53AM (#56278851)
    A good way to find where a connection is being slowed is to use MTR [], or on Windows WinMTR []. It's a combination of ping and traceroute that can show where the network becomes slow, or error rates become high between you are the server you are using.
  • by meerling ( 1487879 ) on Sunday March 18, 2018 @06:20AM (#56278899)
    For many years I've tested my connection on comcast.
    If it's a popular or well publicized test site, comcast gives back great numbers.
    On the other hand, if you use any of the various ways to obfuscate the address, or just use one comcast doesn't have on it's script yet, then you'll see MUCH lower speeds.
    Yes, there are ways to verify that the obfuscation isn't causing the slowdown.

    Short version, comcast slows you down unless they know they're being tested, then they give you a higher bandwidth. I've tested them for close to 10 years now, and it's always the same.
  • where the people live and breath this stuff 24/7/365. []
  • This will sound odd, but try a VPN over the same connection.

    I found my ISP was slowing down all traffic, apart from to and other speed testing sites.
    However, they were not slowing down VPN traffic.

    After running all my traffic for a month over a VPN, my speeds were 10x faster and not slowing down at peak times.
    Then I received a call from my ISP kindly asking me to leave. I'm now with a decent ISP.

  • If you're a Windows user, sometimes the system will switch back to the default ISP's DNS for certain programs (Edge browser *cough cough*) and not just p2p/torrent stuff because, and like we Linux users keep trying to say, they are evil, assuming that all the ads and tracking doesn't give you away or if Micro$oft itself made a deal to throttle on behalf of the ad related conpitition. How else can Cortana give Micro$oft their untainted data fix if your lying to her or get you to use Bing instead of Google? S
  • It tests using Netflix so you can compare to other speed testers. []

  • by pgn674 ( 995941 )
    If you have an Android or iOS device, then download the Wehe [] app and run it while you're connected to your home WiFi. It was developed by university researchers to detect slowdowns of certain streaming services.
  • My ISPs dirty little secret is that it routes all http(s) traffic through a proxy cache server, so most popular websites run load great but everything else is often slow.
  • by alexo ( 9335 )

    You are welcome [].

  • I can't use SFTP to access my Godaddy account over Roger's infrastructure in Canada. I have ISP accounts with Carrytel and Tecksavvy both using Rogers cable infrastructure and my traffic is blocked. However when I use Bell everything works fine. Godaddy support was good, Tecksavvy is always amazing but we couldn't resolve it and rogers was completely unhelpful.

    Has anyone else experienced this and been able to resolve it?
  • Last night netflix movies would simply get to 20% (of the way to starting the movie) and stop, meaning the movie never actually started. In every case it got to 15% or up to 23% further. I tried several times on each of several movies.

    Switched to amazon prime and no delay, fast response, worked fine right away.

    I was asking myself how I could check on comcast (the only ISP available here).

    It's a TV, so no obvious way to run a speed test on it.

  • by jd ( 1658 )

    1. Use pchar to establish the bandwidth and packet loss ICMP sees between endpoints.

    2. Craft packets that contain magic numbers or magic strings, I'm pretty sure that's hping, and see if there are behaviours that only occur with given sequences regardless of endpoints.

    3. Traverse the same segment of net using an encrypted tunnel, as encryption is slow. If this causes a massive acceleration, then it cannot be explained by a change in path, only by a change in visibility.

    4. Use a proxy that is on the other si

  • Your ISP probably doesn't slow down anything. It's just that they didn't partner with the content delivery networks of some popular services. There are often disagreements on who is going to pay... As a result, all Netflix or whatever traffic goes through small pipes that are not designed to handle such heavy loads.

    If you notice that speeds vary during the day, with prime time being the slowest, than that's must be what happens. The mitigation is to force the data to take a different path, one that is not s

  • by GerryGilmore ( 663905 ) on Monday March 19, 2018 @12:14AM (#56282101)
    ....let me say that I very much appreciate the feedback from the /. community. As usual, a varied mix of great input, doom-mongering and nonsense. What I love about /. !!
  • Comcast has more lobbyists and lawyers than you. You'll never win. Ever.

    Unless you just want to prove the point for argument's sake.

    Then I bid you godspeed, sir.

No problem is so large it can't be fit in somewhere.