By Marguerite Reardon , CNet News.com
Mar 13, 2008

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A real-world Internet test reveals that "intelligent" routing of peer-to-peer traffic can drastically reduce network utilization and speed up downloads for subscribers, according to a new study.

Verizon Communications, which participated in the study headed by researchers at Yale University, plans to release the data on Friday at the Distributed Computing Industry Association's P2P Market Conference in New York City.

Using network topology data from Verizon and Telefonica, Yale University tested a software enhancement to the peer-to-peer protocol that it developed with software developer Pando Networks.

What the researchers discovered was that when using the so-called P4P software they were able to reduce the impact of peer-to-peer traffic on Verizon's network by more than 50 percent. This is significant because peer-to-peer traffic makes up roughly half of all traffic traveling over Verizon's network.

Traditionally, the P2P protocol has requested bits and pieces of content randomly, without considering the physical location of the data. This often results in some pieces of the content traveling over long distances across the network. For example, a user in New Jersey downloading a movie might get some bits of the file from New York and others from China or California.

The P4P software enhancements add intelligence to this process so that the bits are served from local hosts.

Douglas Pasko is Verizon senior technologist and co-chair of the P4P Working Group, which was formed by Verizon, Pando Networks, and the university to develop P4P. He said that when the P4P software was used on the Verizon network it found that 58 percent of its peer-to-peer network traffic stayed local. Using regular P2P technology, only 6 percent of the traffic stayed local.

Pasko said that keeping the traffic local is important because every link that a bit passes through costs the operator something. This means that if a Fios subscriber in New Jersey can get bits of content from Verizon customers in New York City instead of getting them from Singapore or Taiwan, Verizon can save money.

The key is reducing the number of routers or hops the traffic has to go through to get to its destination. On average, Pasko said that regular P2P traffic makes 5.5 hops to get its destination. Using the P4P protocol, those same files took an average of 0.89 hops.

Reducing hops means that Verizon can cut its network costs. Exactly how much the company saves depends on the individual links, but Pasko said the savings are significant.

Verizon broadband subscribers also saw a benefit when the P4P protocol was used. Customers using Verizon's all-fiber network called Fios saw movies downloading on average twice as fast as when they used the traditional P2P software. Some customers saw as much as a 6x improvement in download speeds, Pasko said.


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