Throttling P2P traffic is shortsighted, experts say

Throttling is a short-sighted strategy to deal with peer-to-peer (P2P) traffic congestion, computer science experts say.

Instead, they say, a new model for file sharing on P2P networks would not only result in faster download times for users, but also offer relief to bandwidth-strapped carriers.

Bell Canada is currently waiting to hear the Canadian Radio-Television Commission’s (CRTC) verdict on its traffic-shaping practices.

The Commission is reviewing a petition by the Canadian Association of Internet Providers’ (CAIP) that Bell Canada “cease and desist” its traffic throttling practices.

Bell counters that this practice is necessary as there’s just not enough bandwidth to allow P2P traffic to go unchecked.

But now research out of the University of Washington and Yale University suggests there might be a solution.

On Thursday computer scientists presented a paper in Seattle that describes a test conducted on a protocol that takes a new approach to P2P traffic.

The protocol is dubbed “P4P” by researchers to reflect its upgrade.

But a more accurate name comes from U.S. carrier Verizon, says Lawrence Surtees, vice-president at Toronto-based consulting firm IDC Canada.

Verizon and other companies interested in the protocol call it “P2P with intelligent routing.”

“I like that phrasing better because it’s another iteration of application network routing technology, similar to when digital routing really took off,” he says.

To solve the P2P deployment problem, carriers simply have to take a page from a book telecom network operators already wrote two decades ago.

P2P allows a user to download a large file in smaller chunks from many different sources simultaneously.

The approach to fixing P2P is a simple concept – location, location, location.

Right now, only six per cent of file sharing is done locally, say researchers, but with their new algorithms that can be increased to 58 per cent. With fewer hops between different servers, the traffic will become more efficient.

Users downloading P2P files would find either the same performance or a 20 per cent increase in speed. But the real difference is made with the carrier, as P4P could reduce network load – making it five times less than that used by P2P.

The success of the new approach depends on the willingness of ISPs to cooperate with content providers, say study co-authors, Arvind Krishnamurthy from the University of Washington and Richard Yang from Yale.

“I don’t think throttling is a good approach because it’s not good for the applications, and the consumers have a bad experience,” Yang says.

P4P offers a much better solution, he adds. It could reduce resources needed by the ISP to support the traffic, and lower costs while benefiting content providers with faster download speeds. So it’s in the carrier’s interest to co-operate and make P4P work.

P2P applications will need to infer various types of network information such as topology, congestion status, cost and policies, the study says. “Reverse engineering of such information – in particular cost and policy information – is challenging if not impossible.”

Networks would have to provide a communications channel to content providers to improve the traffic flow, it adds.

Interfaces are built into P4P to do this anonymously with a view to protecting the privacy and confidentiality of carrier’s information.

But carriers working with P2P content providers isn’t the norm in Canada.

The file-sharing protocol gets a bad rap because it is popular among software pirates. Bell has decided to throttle all P2P traffic, claiming that five per cent of users are hogging almost all of the network bandwidth.

The study’s authors decry the use of deep packet inspection for use in traffic shaping. The technique should be reserved for controlling edge traffic demands only, they say.

“Unilateral rate limiting by ISPs can be considered strong handed and may lead to P2P reactions such as encryption and dynamic ports to avoid being identified,” the study says.

But Verizon’s interest in the protocol could signal a turning point in the telecom industry’s approach to P2P, Surtees says.

The U.S. company, he notes, has broken ranks with the rest of the sector, saying it supports a technology that allows users to get faster download speeds.

Surtees predicts the technology will emerge as more popular over the next five years, and ISPs like Bell will need to change their game plan.

P2P file-sharing is emerging from the pirate underground and into the mainstream already.

Broadcasters have started releasing TV shows through torrents, with the CBC releasing an episode of Canada’s Next Great Prime Minister. Select musical talents have also shown interest in the medium, such as Trent Reznor, front-man for Nine Inch Nails, who gave away a free album to fans via torrent.

“P2P is finding commercial applications today,” Surtees says. “So I think it behooves ISPs around the world not just to live with it, but to harness it.”

The Abilene network hosted a P4P test.

Researchers tested a P4P infrastructure on the Abilene network in the U.S., an Internet backbone used by many educational institutions. Using P2P technology, an Abilene client on the West coast many choose to download a file from a user on the East coast even if it could find a closer option.

“Such long distance peering is not only inefficient to the network but might also lead to lower application performance,” the study says. “Clearly, this inefficiency should be avoided by choosing a low-latency or small hop-count peering, and the resulting locality could reduce the network load.”

In tests using the BitTorrent application on the network, the P4P version outperformed a native P2P version. Downloads were completed up to 20 per cent faster and the bottleneck traffic was also reduced by three times.

P2P traffic accounts for as much of 80 percent of all Internet traffic (half by other accounts). But everyone agrees it is growing.

Meanwhile, a Canadian ISP is currently working with the researchers to conduct a test of the technology, Yang says. The name of the company won’t be revealed right now, but “it’s one of the largest ISPs in Canada.”

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