By Ryan Paul, Ars Technica
Mar 14, 2008

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The Distributed Computing Industry Association's P4P workgroup is devising a new protocol for what researchers describe as carrier-grade peer-to-peer file transfer systems. Verizon reports that a recent test it conducted revealed that the new protocol provides a significant boost in download performance while simultaneously reducing network congestion.

P4P, which stands for Proactive network Provider Participation for P2P, ultimately aims to decrease backbone traffic and bring down network operation costs by enabling service providers to communicate information about network conditions to client applications for the purpose of facilitating improved P2P file transfer performance. Instead of selecting peers at random, the P4P protocol leverages network topology data so that peers can be selected in a manner that increases routing efficiency.

Ars spoke with Verizon senior technologist and P4P workgroup co-chair Doug Pasko, who tells us that Verizon observed download performance improvements of approximately 200 percent during tests conducted with Pando. The performance boost can climb as high as 600 percent in some cases. Verizon believes that P2P technology is moving into the mainstream and is being legitimized for large-scale commercial content delivery. The company sees P4P as a way to enable broader commercial adoption of P2P tech while unclogging the tubes and relieving network congestion.

Since the efficacy of the P4P protocol largely relies on the availability of network topology information, Verizon and the P4P workgroup aim to make the new protocol an industrywide standard and convince other carriers to share their own data and participate. "Quite frankly, any carrier should benefit from this," Pasko told Ars. The initiative has drawn support from a number of ISPs, including Comcast, which is currently facing scrutiny for impeding peer-to-peer traffic on its own network.

In a paper published by the P4P group, "P4P: Explicit Communications for Cooperative Control Between P2P and Network Providers," researcherslook at some of the unique advantages of P4P compared to other solutions. The report notes that traffic-shaping technologies that rely on deep packet inspection to throttle P2P are easily thwarted by client applications that encrypt traffic and use dynamic ports to evade identification. Without the cooperation of the actual P2P services, the report says, no solution will succeed. "It remains unclear whether in the long run traffic shaping can effectively control the bandwidth consumption of P2P applications and reduce provider's operational costs," the paper's authors note. "By enabling explicit communication between P2P and the network, P4P can enable applications to use network status information to reduce backbone traffic and lower operation costs."

The implication is quite clear: network operators can more effectively cut costs by enabling better P2P rather than trying to impede it. The question that remains is whether this solution will be extended to all P2P traffic, or just services favored by ISPs and Big Content. Verizon condemns illegal filesharing and says that the new protocol is intended for adoption by legal commercial services, but also reiterates thatunlike AT&Tthe company has no intention of policing its own network. Regardless of the implications for piracy, Verizon believes that P4P is an important step towards solving the problems that peer-based file transfer technologies pose to network management.

Further reading

* P4P workgroup: P4P: Explicit Communications for Cooperative Control Between P2P and Network Providers (PDF)
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