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Tests reveal Comcast meddles with P2P network connections

Independent testing performed by the AP has revealed that Comcast actively interferes with peer-to-peer traffic going to and from its high-speed internet subscribers, by impersonating users’ machines and sending fake disconnect signals.
While traffic shaping – the act of throttling a given piece of Internet traffic based on its type, like BitTorrent or VOIP – is becoming increasingly common amongst ISPs interested in preserving quality of service, it seems that Comcast is one of the first companies that actively impersonate individual connections. Most providers will simply slow down some traffic in favor of others, or block a protocol’s port number to prevent it from functioning.
According to the report, Comcast’s technology affects users across many different networks, including e-Donkey, Gnutella, and BitTorrent. Robb Topolski, a former software quality engineer at Intel and Comcast subscriber, began to notice unexplainable performance problems with his P2P software. Posting to the popular forum, he collected similar reports from other Comcast users around the country.
In the case of BitTorrent, Comcast’s technology only kicks in when a user’s client has a complete copy of the file and is uploading it to other users, and not while downloading.
Comcast spokesman Charlie Douglas would not comment directly on the matter, instead only saying, “Comcast does not block access to any applications, including BitTorrent.”
There are currently very few regulations regarding traffic shaping, and none that specifically cover Comcast’s particular use. The FCC says that while consumers are entitled to run the applications and services of their choice, they are subject to measures of “reasonable network management” by their ISPs. The closest directive governing Comcast’s behavior – which still doesn’t directly apply – would be found in AT&T’s conditions for acquiring BellSouth, where it had to agree not to manipulate traffic in any way based on its origin – not service type.
Comcast’s “traffic discrimination” has important ramifications for the growing number of services that are leveraging P2P as a means to distribute large files quickly and cheaply. A company like Blizzard Entertainment, who relies on BitTorrent for distributing World of Warcraft updates that often measure hundreds of megabytes in size, may have trouble reaching its players if it or they are behind a Comcast internet connection. This problem will only worsen if other ISPs decide on a similar course of action.
Ashwin Navin, co-founder and president of BitTorrent Inc. confirmed the AP’s findings, and noted that he has seen similar practices from several Canadian ISPs.
“They're using sophisticated technology to degrade service, which probably costs them a lot of money. It would be better to see them use that money to improve service,” said Navin.

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Just testing
By SunAngel on 10/19/2007 10:31:40 PM , Rating: 2
My uneducated guess is Comcast is testing how their filters will react once pay-per-usage fees are in favor of unlimited service. Assuming BT become popular to the point of commonman using it to download Vongo, MovieLink and what-nots this would be an effect way to ensure constant and fair traffic for all.

However, if there are 50+ subscribers on the same bus and everyone is online at 7PM grabbing yesterday's HDTV CSI episode, it makes sense Comcast should limit certain MACs if other MACs can't reach their destinations or retrieve their information. What do you think? Holler back.

RE: Just testing
By ted61 on 10/19/2007 10:48:46 PM , Rating: 5
That is the reason I use a slow dsl connection. I do not like Comcast limiting my bandwidth for any reason. If they sell me X amount of bandwidth for X amount of money, they should supply what they sell. If they sell you unlimited upload at 3mbps they should deliver 3mbps for the whole month with no caps. Unlimited means unlimited.

RE: Just testing
By Spivonious on 10/22/2007 9:13:00 AM , Rating: 2
They don't sell you that though.

Actual speeds may vary and are not guaranteed. Many factors affect download speed.
- taken from
Comcast's website.

RE: Just testing
By Christopher1 on 10/22/2007 11:46:00 AM , Rating: 3
Actually, they do sell you that. That means that OTHER factors outside of Comcast's control will affect downloading speeds...... NOT things Comcast themselves are doing.

RE: Just testing
By mindless1 on 10/20/2007 2:40:33 AM , Rating: 2
What we all think is Comcast is spending money to reduce full use of the subscriber's accounts instead of spending that money towards the bandwidth the system needs if a lot of users were to d/l CSI at once.

There is no evidence of this though, that it's only being done when their lines are saturated. On the contrary if this were the case people would be reporting overall problematic usage not just bt failures.

RE: Just testing
By TomCorelis on 10/20/2007 3:41:45 AM , Rating: 1
If BT is working right and preferentially selecting peers based on ping (does it do that?), a lot of that download traffic wouldn't leave Comcast's network or even the neighborhood, as all the neighborhood peers would hopefully help each other out.

"And boy have we patented it!" -- Steve Jobs, Macworld 2007

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