Comcast Throttles BitTorrent Traffic, Seeding Impossible
Over the past weeks more and more Comcast users started to notice that their BitTorrent transfers were cut off. Most users report a significant decrease in download speeds, and even worse, they are unable to seed their downloads. A nightmare for people who want to keep up a positive ratio at private trackers and for the speed of BitTorrent transfers in general.
ISPs have been throttling BitTorrent traffic for almost two years now. Most ISPs simply limit the available bandwidth for BitTorrent traffic, but Comcast takes it one step further, and prevents their customers from seeding. And Comcast is not alone in this, Canadian ISPs Cogeco and Rogers use similar methods on a smaller scale.
Unfortunately, these more aggressive throttling methods can’t be circumvented by simply enabling encryption in your BitTorrent client. It is reported that Comcast is using an application from Sandvine to throttle BitTorrent traffic. Sandvine breaks every (seed) connection with new peers after a few seconds if it’s not a Comcast user. This makes it virtually impossible to seed a file, especially in small swarms without any Comcast users. Some users report that they can still connect to a few peers, but most of the Comcast customers see a significant drop in their upload speed.
The throttling works like this: A few seconds after you connect to someone in the swarm the Sandvine application sends a peer reset message (RST flag) and the upload immediately stops. Most vulnerable are users in a relatively small swarm where you only have a couple of peers you can upload the file to. Only seeding seems to be prevented, most users are able to upload to others while the download is still going, but once the download is finished, the upload speed drops to 0. Some users also report a significant drop in their download speeds, but this seems to be less widespread. Worse on private trackers, likely that this is because of the smaller swarm size
Although BitTorrent protocol encryption seems to work against most forms of traffic shaping, it doesn’t help in this specific case. Setting up a secure connection through VPN or over SSH seems to be the only solution. More info about how to setup BitTorrent over SSH can be found here.
Last year we had a discussion whether traffic shaping is good or bad, and ISPs made it pretty clear that they do not like P2P applications like BitTorrent. One of the ISPs that joined our discussions said: “The fact is, P2P is (from my point of view) a plague - a cancer, that will consume all the bandwidth that I can provide. It’s an insatiable appetite.”, and another one stated: “P2P applications can cripple a network, they’re like leaches. Just because you pay 49.99 for a 1.5-3.0mbps connection doesn’t mean your entitled to use whatever protocols you wish on your ISP’s network without them provisioning it to make the network experience good for all users involved.”
Customers on the other hand like to fully use their connection, and don’t agree that traffic shaping is the correct solution. One reader commented: “If you pay for an internet connection, that’s what you should get from your ISP — an internet connection. Not a connection that will let you browse the web and check email, but little else. If an ISP has issues with the amount of data a customer is transferring, then the ISP needs to address that issue with that customer, and not restrict every user in one class of traffic.”
I guess this battle will go on for a while and I would advise Comcast users to try setting up a VPN connection to get around the traffic shaping, other users who find out that they are throttles might try BitTorrent encryption first, that seems to work quite well in most cases.
More details about the Sandvine application can be found here.
Previously: BitTorrent Anime Downloaders Identified, $3500 Bill in the Mail
Next: TorrentPod Episode 43
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furk.net/bt/ is the solution
[quote comment="148260"]furk.net/bt/ is the solution[/quote]
Not really a solution, and it’s not a free service either.
I’m with Sympatico (Canada), very loose leash as far as I know. :)
Time to find a new ISP then. Sadly, it appers to be a lack of good ISPs in the US. Any suggestions of one that doesn’t throttle any P2P-traffic?
I am as of today the 17th of August a Comcast cable internet subscriber. I’m not sure if this is affecting all Comcast or possibly untrue, but I am currently downloading/seeding without any issues. I seed on timer where day,early evening hours i upload at 32kb/s and late evening early morning at 64 kb/s and have done so for almost 2 years on a 24/7 basis with no problems from Comcast for doing so. I’ve up’d over 500 Terabytes this year so far, and that’s just in bitorrent traffic. I still use my net connection for games and surfing/email as well on top of this. I live in a smaller area so this may be the reason we aren’t affected. I can’t say anything bad about Comcast as of this time period. I had issues with sprint/earthlink dsl and their crap speeds before this but comcast has been reliable and almost always higher than rated speeds.
“P2P applications can cripple a network, they’re like leaches. Just because you pay 49.99 for a 1.5-3.0mbps connection doesn’t mean your entitled to use whatever protocols you wish on your ISP’s network without them provisioning it to make the network experience good for all users involved.”
Funny. Then don’t oversell the lines. What about the BBC story, how ISP’s want money from the BBC for shocking there connections because of the high demand for the BBC’s TV player.
If you sell a 3Mbits line, then you need to be sure, it can handle 3Mbits when everybody is using 3Mbits. They oversell like hell. Overselling = profits. And if people use to much bandwidth, then lets just throttle whatever application they are using.
We have seen this same problem going back almost 7 years? When a local cable isp advertising 10Mbits, but download limit of 10GB/month. Blaming the “rotten” apple’s for consuming to much downloading “illegal” material. We are 7 years later, and yet, its still 10GB/month ( unless you are willing to pay a hefty 1€/GB fee. Then they sky’s the limit ). Funny, when you can have servers with a 1.5TB limit in the neighboring country for only 19€’s month.
ISP’s run behind the facts, and refuse to see that p2p, webtv, youtube, and other bandwidth “devowering” services rule these days, and will so in the future.
I’m on Sympatico too … from back in the days with unlimited downloads. If I were to sign up as a new customer I either have to pay extra for unlimited or get a total of 2GB (that’s for both upload and download) and then pay extra.
With a total monthly transfer (upload and download) of 100GB to 240 GB I’d have to pay a fortune for my connection. Paying for bandwidth is the right way for limiting P2P though.
[quote comment="148279"]Time to find a new ISP then. Sadly, it appers to be a lack of good ISPs in the US. Any suggestions of one that doesn’t throttle any P2P-traffic?[/quote]
I have Verizon FiOS and I love it. No restrictions as far as I know, and I get 15Mb/s down and 2Mb/s up for about $50 a month.. not bad at all.
Unfortunately FiOS isn’t available in most places yet.. but worth looking into.
I was looking at the Azureus wiki and it said you can try the ‘Use lazy bitfield’ option.
iptables -A INPUT -p tcp –dport $TORRENT_CLIENT_PORT –tcp-flags RST RST -j DROP
is the solution, and soon torrent clients / peerguardian and alike hopefully implements it for windows aswell =)
I fucking hate Comcast. I need a new broadband provider. God fucking damn it, this fucks my day over.
Yeah I noticed that. I was seeding a Catalan movie, there are very few of us on the net and I had major problems getting the seed to work, the peers kept going off all the time. Luckily I have a vpn to work where I admin, so I used that to get over this irritation.
first the anime thing now this. i fucking give up.
Use Hamachi to establish giant secure virtual lans on the internet. Its free, cheap, easy.
I personally have the “bogomip” network with a private password using the Hamachi servers. I use that for my personal home to work VPN, took maybe 5 minutes to set up and get working.
If torrent sites would use hamachis P2P encrypted VPN techniques to make a large virtual lan exist, they could privately host their own websites on private networks - outside of the public eye.
“If you sell a 3Mbits line, then you need to be sure, it can handle 3Mbits when everybody is using 3Mbits. They oversell like hell. Overselling = profits.”
You are one clueless moron. Why can’t you understand that “up to 3 Mbps” does not mean “3 Mbps 24/7?” How on Earth do you expect any ISP to keep their doors open if they allow bandwidth hogs to max out connections as they see fit, when a 45 Mbps DS3 connection costs them thousands of dollars per month? Should they only allow 15 customers per DS3 and then charge them $500 or more per month? I’d love to see you pissing and moaning then, you ignorant wanker.
Bottom line — ISP’s are BUSINESSES that have EXPENSES and also need to make some form of PROFIT. If you’re maxing out your connection all the time, you’re not profitable, and therefore your ISP should restrict your ass or just cancel your service all together.
Get a clue.
- Tate
Tate,
Then ISPs need to change the way they advertise. Something like “At least .5mbps, up to 3mbps”.
PYT -
I can accept that. In fact, I’m all in favor of ISP’s using an “up to” rating for speeds as long as they are completely open about the stipulations on the connection. If they’re going to throttle, then that’s their right to do so in order to maintain a good connection for other users. A simple disclaimer on their website stating “P2P traffic is limited to xyz Kbps” or something similar should make everyone happy; the ISP is maintaining network performance, and bandwidth hogs know point blank what their limitations are. Make sense?
There’s also adaptive traffic shaping, such as throttling only during certain peak hours of the day.
Really, there are lots of possibilities if ISP’s are willing to go above and beyond to provide a good product for everyone, yet maintain their profitability.
My $.02 worth.
- Tate
COMCAST IS THE WORST EVER. PRICE KEEPS GOING UP .MY INTERNET GOES OUT ALL THE TIMW . CABEL CHANNELS SUCK . THEY SHOW THE SAME OLD CRAP.
Comcast wants you to quit: If they only have low-usage users who are overpaying for their connections, they win.
Most of you are the techies who know lots of other folks. Instead of leaving Comcast, help your parents, friends, etc upgrade to someone who provides Internet service as opposed to limited IP connectivity.
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