A STUDY conducted by a respected German scientific institute found that the big US cable Internet Service Providers (ISPs) Comcast and Cox are actively blocking about half of all Peer-to-Peer (P2P) requests practically all the time.

Germany's Max Planck Institute noted a Cnet report that Comcast defended its blocking of BitTorrent P2P traffic to the FCC (pdf) "as a necessary practice that is done only during periods of heavy network traffic."

Observing "It is widely known that network traffic exhibits a strongly diurnal pattern," that is, more active during daytime than nighttime hours, researchers collected and analysed data "to see if hosts in Comcast and Cox networks see fewer of their upstream transfers blocked during early morning or weekends (when network load is generally low) than during other times of the day."

The study findings put the lie to the cable ISP companies' claims that they are only engaging in legitimate 'network management' during periods of 'network congestion' caused by high traffic demand. To the contrary, testing found that cable ISPs blocked BitTorrent upload traffic "independent of the time of day."

The Max Planck Institute collected data between March 18 and May 15 from 8,175 unique hosts that ran its BitTorrent tests. Participating hosts were in 90 countries, connected through 1,224 ISPs, and ran the 'Glasnost' testing tool.

The only locations where cable ISPs blocked BitTorrent traffic to a significant extent were in the United States (Comcast and Cox) and Singapore (Starhub).

Tests showed that Comcast blocked at least 30 per cent of BitTorrent upload attempts and, during most hours, Comcast blocked between 50 to 80 percent of BitTorrent traffic. Cox blocked at least 20 per cent of BitTorrent uploads (except for one period at 3 AM where one request wasn't blocked) and, during most hours, Cox blocked between 50 to 100 per cent of all BitTorrent traffic.

The BitTorrent traffic was blocked, not managed. In its report, the Max Planck Institute clearly noted, "ISPs may throttle (rate-limit) BitTorrent traffic without blocking it. The results we present here are limited to hosts whose BitTorrent transfers to our servers are blocked, i.e., interrupted by RST [Reset] packets generated by some ISP along the path."

The Institute found that "All hosts which [the tests] observed blocking did so in the upstream direction (i.e., when the client host attempted to upload data to one of our Glasnost servers). Only a handful of hosts [were] observed blocking for downstream BitTorrent transfers."

It also discovered that only cable ISPs were implicated in blocking BitTorrent traffic. "Both in the U.S. and in Singapore, all hosts that suffered BitTorrent blocking are located in cable ISPs. We did not see any blocking of BitTorrent transfers from DSL hosts in these countries."

According to IT World, Comcast PR spinner Sena Fitzmaurice tried to dismiss the report, saying that P2P traffic comprises 50 to 90 per cent of network load and can occur at any time, meaning that network congestion due to BitTorrent traffic doesn't happen only during daytime hours. She said, "P2P traffic doesn't necessarily follow normal traffic flows."

Fitzmaurice added that the users who participated in the Institute's 'Glasnost' testing might not be representative of Internet users overall. She said they might be "heavy users of P2P." That implies that Comcast might have already targeted those users for more frequent blocking of their BitTorrent activities.

Even in the face of the strong evidence provided by the Max Planck Inst itute's 'Glasnost' study, Comcast continued to defend its heavy-handed P2P blocking practices. It released a statement repeating its contention that it " does not, has not, and will not block any Web sites or online applications."

The statement went on to repeat the company's line that it is merely engaging in 'network management' saying, "We have acknowledged that we manage peer-to-peer traffic in a limited manner to minimize network congestion."

Comcast also provided a vaguely worded assurance that it's endeavoring to mend its ways, stating "While we believe our current network management approach was a reasonable choice, we are now working with a variety of companies including BitTorrent [to] move to a protocol-agnostic network management technique." Comcast announced talks with BitTorrent in March.

Cox had no comment on the study's findings. The results also found some intermittent blocking of BitTorrent traffic by 11 other ISPs besides Comcast, Cox and Starhub, seven of which were in the US, but the Institute said that interference by those other ISPs did not amount to "widespread" blocking.

The Max Planck Institute's 'Glasnost' study results underscore FCC chairman Kevin Martin's recent testimony before a US Senate committee. In April, he told the committee that Comcast appeared to be widely imposing its blocking of P2P traffic. He said that Comcast seemed to "block uploads of a significant portion of subscribers" even during times when its network wasn't congested.

Martin told the Senators that, "Based on testimony we've received thus far, this equipment was typically deployed over a wider geographic area or system, and is not even capable of knowing when an individual ... segment of the network is congested."

That would certainly go a ways towards explaining these cable ISPs' evidently widespread P2P blocking, but at the same time it thoroughly demolishes their la me 'network management' excuse for doing it. If they cannot discern when a particular network segment is congested, then they simply cannot be blocking P2P traffic to manage it but must be doing so randomly, just because they can.

Then there's also that hint by Comcast spokesperson Fitzmaurice that perhaps Comcast blocked 'Glasnost' test participants' BitTorrent uploads because they were "heavy users of P2p." If that's true, it's outrageous, unfair discrimination, especially in view of the cable ISPs' advertisement of unlimited Internet access.

If, as the cable ISPs claim, at least 50 per cent of their network load consists of P2P traffic, and if, as this study indicates, they are blocking 50 per cent of that on average, and if, as both this study and FCC testimony have established, that blocking cannot be justified as necessary for 'network management', then the cable ISPs are in breach of their broadband subscriber contracts for rejecting approximately 25 per cent of their subscribers' network transport requests.

By this logic, Comcast and Cox customers ought to be entitled to 25 per cent reductions in their Internet access charges, plus rebates for past overcharges.

Can Comcast and Cox subscribers spell 'class-action lawsuit'? Attorneys can.

The Open Internet Coalition, Public Knowledge and Free Press have cited the Max Planck Institute's 'Glasnost' study in support of the proposition that the US Congress should enact Network Neutrality legislation that would prohibit ISPs from blocking any Internet traffic or favouring certain types of content, or traffic from specific sources, over other types of content, traffic or sources.

"Consumers have no reason left to trust their cable company," said Ben Scott, policy director of Free Press, in an email to IT World.

Referring to the Institute's 'Glasnost' study, he further said that " sophisticated testing shows that Comcast and Cox block BitTorrent applications at all times of the day -- not just at times of peak traffic. Now is the time to send a clear signal to the market that blocking consumers' access to the lawful Internet content of their choice is out of bounds."

Network Neutrality legislation is clearly needed to rein in these arrogant cable ISPs, because in many US metropolitan area markets they have no competition for broadband Internet access. µ

See Also
Vuze offers help to detect ISP's P2P blockage
Comcast hates FCC chairman - official
Comcast stacked Net Neutrality meeting
FCC to curb ISP 'traffic management'
Net Neutrality bill is introduced in the US Congress
Comcast tried to stonewall the FCC
FCC investigates Comcast
Comcast reported to FCC
Cable vendors could face lawsuits for P2P blocking
Comcast P2P blocking spurs calls for Net Neutrality

L'Inqs
Max Planck Institute
IT World