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Harnessing the power of P2P

It may have gotten a bad rap, but peer-to-peer technology is increasingly used as a legitimate distribution tool for high-bandwidth applications like video.

Peer-to-peer technology has gotten a bad rap for years, but a group of Internet service providers led by Verizon Communications is working to harness the technology to reduce network traffic and speed up video downloads on the Web.

Since the days of file-sharing networks like Napster, which allowed people to exchange songs on their computer hard drives with others on the Internet, peer-to-peer technology has been demonized in the press. The entertainment industry has pegged it as a tool for piracy. And recently, ISPs have blamed it for clogging their networks.

But the technology, which was originally developed for the research community to share huge files over the Internet, is increasingly being used by legitimate video distribution services like the BBC's iPlayer, voice over Internet Protocol service Skype, and Internet video start-up Joost. And as more high-bandwidth applications like video make their way onto the Web, peer-to-peer, or P2P as it's commonly called, will be used even more. This means that Internet service providers and content owners will have to find ways to work with the powerful P2P technology--whether they want to or not--if they hope to survive.

"Peer-to-peer has entered the mainstream," said Cynthia Brumfield, president of the market consultancy Emerging Media Dynamics, which is publishing a report on the P2P market next week. "The technology is being used by companies large and small for legitimate commercial purposes and with good reason. It's a very efficient distribution technology. But it has to be managed, and that's what needs to be figured out. "

"Peer-to-peer has entered the mainstream...It's a very efficient distribution technology. But it has to be managed, and that's what needs to be figured out."
--Cynthia Brumfield, Emerging Media Dynamics

In an effort to come up with a solution, Verizon Communications and P2P technology provider Pando Networks joined forces last year with researchers at Yale University to figure out a way to put the file-sharing technology to better use. The companies and the university formed the P4P Working Group (P4PWG) within the Distributed Computing Industry Association (DCIA) . So far the group has signed up nine other members to the cause. These companies include other big telephone companies, such as AT&T and Telefonica, as well as big technology companies like Cisco Systems and Verisign.

Using basic subscriber information from ISPs, researchers claim to have developed a solution that can reduce a provider's P2P bandwidth consumption on their networks by about 60 percent, while also speeding up P2P downloads by nearly a third. This month, Verizon and Pando will start testing the new system on a real network in the U.S. AT&T and Spanish ISP Telefonica also plan to conduct tests.

Assessing the problem
Broadband providers, particularly cable operators, have complained that P2P traffic is eating up too much bandwidth on their networks. They say that the use of P2P, which assembles large data files like video by requesting bits of content from "peers" in the network, is crippling their networks.

And as a result, they have started to take action. Last year Comcast, the largest cable operator in the U.S., was accused of blocking the P2P application BitTorrent on its network. The service provider denied it was blocking traffic and said it had slowed down the BitTorrent packets in an effort to better manage its network.

Subscribers, who didn't like this brute-force solution, became furious. Complaints were filed with the Federal Communications Commission, and the company's practices are currently being investigated by the agency.

Other service providers have also taken action. AT&T says that it is testing content filtering technology to identify copyrighted material to reduce the amount of P2P traffic traversing its network. And Time Warner Cable, the second largest cable operator in the U.S., said it is experimenting with a new business model where heavy bandwidth usage will be metered to reduce P2P usage.

"P2P traffic is a big problem for our network" said Alex Dudley, a spokesman for Time Warner. "But more importantly it can be a nuisance for our customers, because it slows down their service. If a few customers are using an inordinate amount of bandwidth they should pay for it."

The reason that P2P is such a problem for some service providers is that they never designed their networks to allow for massive transfer of data both on the downlink, as well as, the uplink. P2P applications work by leveraging files that are distributed throughout a network.

So instead of broadband subscribers downloading a movie from a central server farm, a P2P application requests pieces of the movie from "peers" on the network who have already downloaded the same movie. This distributed model is a much more efficient and cost effective way for distributing large files than the traditional client-server model, but it requires that users have high-speed uplinks as well as high-speed downlinks.

Broadband networks today, and cable broadband networks in particular, are designed to give much more capacity on the downlink than on the uplink. For example, Time Warner Cable sells a broadband service that allows downloads at up to 10 Mbps but uploads at only 512 kbps. By contrast, Verizon, which has been deploying fiber directly to customers' homes, offers a service with downloads at 15 mbps and uploads at 2 Mbps.

Regardless of whether their infrastructure can support P2P traffic, the floodgates are now open and are not likely to close.

This is especially true as more video comes online. Because P2P leverages "peers" in the network to host pieces of content, media companies and video distribution services don't need to spend millions of dollars building out their own server farms and high-speed infrastructure.

"P2P allows you to deliver content that otherwise would be too expensive to deliver over the Internet, like high-definition video," said Doug Pasko, who represents Verizon and is co-chair of the P4P working group. "And not to sound too Internet altruistic, but keeping the cost down using P2P also helps level the playing field a bit, so if a guy in a garage wants to produce and distribute his own movies, he can do it the same way a big studio can."

Making use of P2P
The cost-effective nature of P2P is why large media companies, such as News Corp., the BBC, and NBC Universal are using P2P to distribute their video content. And because it greatly improves the economics of distributing video, the technology also enables a slew of new companies like Joost and Vuze an opportunity to enter the market.

P2P also offers some potential cost savings for Internet service providers.

"P2P follows similar economics to building a broadcast network," said Marty Lafferty, CEO of the DCIA. "In a broadcast model, the same money is spent to deliver video if there is one viewer or 20 million viewers. But on the Internet, each stream costs the network operator money. P2P allows the file to be downloaded once and shared many times. In fact, distribution actually gets more efficient the more people who want the file."

It is this promise of using the network more efficiently that initially sparked the interest of engineers at Verizon. The company is even considering using P2P on its set-top boxes to more efficiently distribute movies on demand, Verizon's Pasko said.

Even though P2P in its current form offers some benefits to service providers, Pasko said the protocol could be refined to offer even more efficiency.

Today P2P traffic often travels along unnecessarily long routes to its destination. For example, someone downloading an episode of The Office in New York may get part of the file from a peer in Singapore even though there are several peers with the same file just down the street or across the river in New Jersey. The P4P solution adds network intelligence to the peering process, so that the P2P applications can make smarter decisions about where they get content.

"If a P2P service can understand how the network is configured to request the file at the closest peers rather than arbitrarily getting it from a peer across the country or around the globe, it could save a lot of network resources," Pasko said. "Every link that a bit passes through costs something. So if I can get the same bits from a Fios customer locally rather than from someone in Singapore or Taiwan, I don't have to use those network resources across the country and under the Pacific."

What's more, Pasko said, using peers that are closer also helps files download faster, making it a win for the video provider as well as the customers.

But to make this intelligent peering scenario work, companies using P2P to distribute content will have to work with network operators around the globe. Historically, ISPs and other network operators have been leery of sharing network information with each other--let alone third parties.

But Pasko said it only takes sharing general information about the network topology and its customers to see some benefit. And because the information shared is not detailed enough to identify individual subscribers, consumers shouldn't fear that their privacy is being violated.

Pasko said he hopes further real world tests will help convince even more carriers to support the working group. Currently, four major cable operators in the U.S.--Comcast, Time Warner Cable, Cox Communications, and Cablevision--have become observers of the working group. And once the group gets enough support, it will begin trying to standardize what and how information will be shared.

"The carriers we've talked to about our results have been very interested," Pasko said. "I think the perception before was that no one really wanted to talk to anyone about solving the P2P issues. But that isn't really the case."