Cox users in our forums have been complaining about peer to peer performance being less than optimal&#46 In particular, they’ve been noting that their upstream p2p throughput has been “weak and random,” though so far this has only been showing up in certain markets. We asked regular user Robb Topolski, who was the first to discover Comcast’s traffic shaping practices, to take a look at Cox connectivity a little more closely.

According to Topolski, Cox is in fact using traffic shaping to degrade p2p traffic. In analyzing a user log, he has concluded that Cox is using traffic shaping hardware to send forged TCP/IP packets with the RST (reset) flag set — with the goal of disrupting eDonkey traffic. He’s been unable to tell precisely what hardware Cox is using, but he notes that the technique being used is very similar to Comcast’s treatment of BitTorrent.

“This capture was on the eDonkey network between a Cox user and a user in Tel-Aviv, Israel,” says Topolski. “In this exchange, the non-Cox user connects, handshakes, and then requests parts, at which time the connection is immediately disrupted by an abort signal (TCP flag RST). The same pattern is repeated for all download requests.”

“This is conclusive proof that Cox is interfering with eDonkey uploads by abusing the RST (abort/reset) flag,” he says.

We asked Topolski if the same practice was being used to disrupt BitTorrent traffic. He noted that thus far there’s just “anecdotal reports that are similar but not proven,” but he’s hoping to dig deeper. We asked Cox for an official statement on whether they block or otherwise impede either BitTorrent or eDonkey traffic, but they did not respond by press time. We’ll of course post their position when we receive it.

Cox and Comcast also both employ caps, though the two companies have taken very different approaches to informing their customers about them. Comcast has traditionally denied that any caps exist, despite the fact they do employ monthly consumption limits that vary based on regional congestion. The company threatens to terminate the connections of users who consume too much, but never specifies what “too much” is.

Cox used to take a similarly cryptic approach to informing customers about caps. However, back in 2003, after fielding numerous customer complaints (most of them from our regular users), the company began stating their service limits very clearly. Customers say these limits are only loosely enforced.

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