Indeed, Xie says, as multimedia becomes more and more dominant on the Internet, demand for P4P implementations will grow, particularly from ISPs seeking to lower the amount of money they need to spend on new fiber and inter-ISP data transmissions. Video and audio streaming from sites such as YouTube and Hulu already accounts for almost 27 percent of global Internet traffic, according to a report by network-management systems vendor Sandvine. Cisco predicts that by 2013, video alone will account for over 60 percent of all consumer Internet traffic. With this kind of increase in high-bandwidth traffic, Levitan says, "we're not going to be able to have the Internet we all want" without P4P, or a similar technology, to help scale the physical networks at a reasonable cost.

Xie and Levitan see two main difficulties for the continued growth of P4P. The first is P2P's association with software, music, and video piracy. ISPs want to make sure that working with P2P companies to improve their service won't make them liable for any illegal file sharing. But Levitan is optimistic that increasing numbers of legal uses for P2P technology will help reform its image. For example, Internet telephony service Skype relies on P2P connections, as does Blizzard Entertainment, maker of the popular online game World of Warcraft. CNN.com began using Octoshape's P2P technology to boost its delivery of live streaming video earlier this year, and the PGA, NBA, and NASCAR all use it to support live webcasts of sporting events.

The other potential problem is perhaps trickier: even though P4P benefits both consumers and ISPs, because it treats P2P traffic differently than other data flowing over the Internet, it could technically violate the Federal Communications Commission's proposed net neutrality regulations. In fact, one of Xie's original motivations in developing the P4P protocols was to help carriers avoid having to limit P2P traffic for cost reasons, as Comcast did--much to consumers' ire--in 2006. He admits that P4P would seem to violate the letter of net neutrality, if not the spirit, by "helping" P2P applications preferentially. "I don't have a good, clear answer to those concerns," Xie says. Still, he and other P4P proponents remain optimistic that the technology's advantages will win the day.

Levitan thinks that the benefits such companies are seeing will allow P4P to move forward. "On a technology basis, and even from a policy basis, I think the FCC could see--wow--this could really help networks, and maybe it changes the network neutrality debate," Levitan says-- because there wouldn't be a scarcity of network capacity anymore.