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does; that's why it's so fast. In principle, peer-to-peer protocols
could help distribute server load across a network, eliminating
bottlenecks. The problem, says Mung Chiang, an associate profes-
sor of electrical engineering at Princeton University (and a member
of last year's TR35), is the mutual ignorance that ISPs and peer-to-
peer networks have maintained in the name of net neutrality.
ISPs don't just rely on the TCP protocol to handle congestion.
They actively manage their networks, identifying clogged links and
routing tra c around them. At the same time, computers running
BitTorrent are constantly searching for new peers that can upload
data more rapidly and dropping peers whose transmissions have
become sluggish. The problem, according to Chiang, is that peer-
to-peer networks respond to congestion much faster than ISPs
do. If a bunch of computers running peer-to-peer programs are
sending tra c over the same link, they may all see their downloads
slow down, so they'll go looking for new peers. By the time the ISP
decides to route around the congested link, the peer-to-peer tra c
may have moved elsewhere: the ISP has e ectively sealed o a wide-
open pipe. Even worse, its new routing plan might end up sending
tra c over links that have since become congested.
But, Chiang says, "suppose the network operator tells the con-
tent distributor something about its network: the route I'm using,
the metric I'm using, the way I'm updating my routes. Or the other
way around: the content distributor says something about the way
it treats servers or selects peers." Network e ciency improves.
An industry consortium called the P4P Working Group---led
by Verizon and the New York peer-to-peer company Pando---is
exploring just such a possibility. Verizon and Pando have tested
a protocol called P4P, created by Haiyong Xie, a PhD student in
computer science at Yale University. With P4P, both ISPs and
peer-to-peer networks supply abstract information about their
network layouts to a central computer, which blends the infor-
mation to produce a new, hybridized network map. Peer-to-peer
networks can use the map to avoid bottlenecks.
In the trial, the P4P system let Verizon customers using the
Fios fiber-optic-cable service and the Pando peer-to-peer net-
work download files three to seven times as quickly as they could
have otherwise, says Laird Popkin, Pando's chief technology o -
cer. To some extent, that was because the protocol was better at
finding peers that were part of Verizon's network, as opposed to
some remote network.
Every technical attempt to defeat congestion eventually runs
up against the principle of net neutrality, however. Even though
BitTorrent Inc. is a core member of the P4P Working Group, its
chief technology o cer, Eric Klinker, remains leery of the idea that
peer-to-peer networks and ISPs would share information. He wor-
ries that a protocol like P4P could allow an ISP to misrepresent its
network topology in an attempt to keep tra c local, so it doesn't
have to pay access fees to send tra c across other networks.
Even David Clark's proposal that ISPs simply charge their cus-
tomers according to usage could threaten neutrality. As Mung
Chiang points out, an ISP that also sold TV service could tier its
charges so that customers who watched a lot of high-definition
Internet TV would always end up paying more than they would
have for cable subscriptions. So the question that looms over every
discussion of congestion and neutrality is, Does the government
need to intervene to ensure that everyone plays fair?
For all Klinker's concerns about P4P, BitTorrent seems to have
concluded that it doesn't. In February, Klinker had joined represen-
tatives of Vuze and several activist groups in a public endorsement
of net neutrality legislation proposed by Massachusetts congress-
man Ed Markey. At the end of March, however, after the Harvard
hearings, BitTorrent and Comcast issued a joint press release
announcing that they would collaborate to develop methods of
peer selection that reduce congestion. Comcast would take a
"protocol-agnostic" approach to congestion management---target-
ing only heavy bandwidth users, not particular applications---and
would increase the amount of bandwidth available to its customers
for uploads. BitTorrent, meanwhile, agreed that "these technical
issues can be worked out through private business discussions
without the need for government intervention."
The FCC, says Clark, "will do something, there's no doubt, if
industry does not resolve the current impasse." But, he adds, "it's
possible that the middle-of-the-road answer here is that vigilance
from the regulators will impose a discipline on the market that
will cause the market to find the solution."
That would be welcome news to Chiang. "Often, government
legislation is done by people who may not know technology that
well," he says, "and therefore they tend to ignore some of the fea-
sibility and realities of the technology."
But Timothy Wu believes that network neutrality regulations
could be written at a level of generality that imposes no innovation-
killing restrictions on the market, while still giving the FCC lati-
tude to punish transgressors. There's ample precedent, he says, for
broad proscriptions that federal agencies interpret on a case-by-
case basis. "In employment law, we have a general rule that says
you shouldn't discriminate, but in reality we have the fact that you
aren't allowed to discriminate unless you have a good reason," he
says. "Maybe somebody has to speak Arabic to be a spy. But saying
you have to be white to serve food is not the same thing."
Ultimately, however, "the Internet's problems have always been
best solved collectively, through its long history," Wu says. "It's held
together by people being reasonable ... reasonable and part of a
giant community. The fact that it works at all is ridiculous."
LARRY HARDESTY IS A TECHNOLOGY REVIEW SENIOR EDITOR.
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