P2P Getting Harder to Stop

BASINGSTOKE, U.K. -- Defensive strategies to control peer-to-peer file sharing that rely on traditional traffic management techniques will soon be outmoded, and may already be obsolete. That's the key finding of a new analysis by Sandvine Incorprated. Available today at www.sandvine.co.uk, "Port hopping and challenges to traffic control methodology" explains how the speed and ingenuity of P2P software development has wrong-footed conventional router and switch technologies. Though service providers are understandably keen to manage the upsurge in peer-to-peer traffic across their networks, the most popular file-sharing clients have evolved features that quickly sidestep traditional techniques to block or throttle their communications. In the past, applications transported via TCP connections have been assigned a specific TCP port, making the traffic easy to identify. But P2P developers have re-designed their applications to use random dynamic ports -- any one of the tens of thousands available. Often referred to as "port hopping," this capability renders traditional port-based P2P blocking and shaping solutions ineffective; and in some cases entirely obsolete. "The range of P2P defenses available to service providers has suddenly become very limited," said Marc Morin, co-founder and chief technology officer, Sandvine Incorporated. "Managing the way this generation of P2P application impacts the network requires techniques that are nimble enough to facilitate easy re-engineering. They must evolve in lockstep with future versions of P2P clients and changes to their underlying protocols." Sandvine's white paper is an adjunct to its well-publicized September 2002 study, "The Impact of P2P on Service Provider Networks." Both are available at www.sandvine.co.uk. Sandvine Ltd.