How Comcast is doing blocking

[<rms () computerbytesman com>]

http://news.yahoo.com/s/ap/20071019/ap_on_hi_te/comcast_data_discrimination_
tests_4;_ylt=Alf7jUPUWXfOtUYue4QQqKEE1vAI

 

AP tests Comcast's file-sharing filter 

By PETER SVENSSON, AP Technology Writer 56 minutes ago 

.

Further analysis of the transfer attempt from the Comcast-connected computer
in the San Francisco area revealed that the failure was due to "reset"
packets that the two computers received, carrying the return address of the
other computer.

Those packets tell the receiving computer to stop communicating with the
sender. However, the traffic analyzer software running on each computer
showed that neither computer actually sent the packets. That means they
originated somewhere in between, with faked return addresses.

In tests analyzing the traffic received by a computer on Time Warner Cable
that was trying to download a file from a large "swarm" of BitTorrent users,
more than half of the reset packets received carried the return addresses of
Comcast subscribers, even though Comcast's 12.4 million residential
customers make up only about 20 percent of U.S. broadband subscribers. It
was the only U.S. Internet service provider whose subscribers consistently
appeared to send reset packets (which are occasionally generated
legitimately).

Comcast subscriber Robb Topolski, who discovered the blocking earlier this
year and traced it to reset packets, pointed out that a Canadian company
called Sandvine Inc. sells equipment that promises to save bandwidth for
Internet service providers by managing and redirecting file-sharing traffic.

BitTorrent Inc. President Ashwin Navin said that the interference method on
Comcast's network is consistent with Sandvine's technology. Sandvine did not
respond to a request for comment.

Comcast spokesman Charlie Douglas would not confirm that the company uses
Sandvine equipment.

"We rarely disclose our vendors or our processes for operating our network
for competitive reasons and to protect against network abuse," he said.

 

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