Microsoft eyes a meaner, 'greener' P2P for Windows 7

Windows Vista already includes a P2P-enabling technology known as Teredo. But for the forthcoming Windows 7, Microsoft is contemplating adding such features as metered connections, distributed hash tables, and something called 'green P2P.'

NEW YORK CITY (BetaNews) - For the Xbox 360 game Halo 3, P2P technology is "key to the whole experience," said See-Mong Tan, Microsoft's director for P2P networking. Now, Tan tells us, the company is pursuing more options that could bring new legitimacy to a technology that is still berated today for its heritage in anonymous file-sharing.

P2P technologies now being considered for the next edition of Windows include "Green P2P," metered connections, and distributed hash tables, Tan said, in a talk at DCIA's P2P Market Conference on Friday.

Tan told attendees at the conference in New York that many Web sites today offer "P2P experiences" even without relying on P2P technologies. On Wikipedia, for instance, "everyone can either edit or read." On YouTube, "anybody can post or watch videos."

But P2P technology, on the other hand, calls for the use of "computer sharing [across a] whole community grid," he said.

Initially, P2P was used for distributing free music over networks such as Napster, and then for unlicensed sharing of movies over eDonkey. "Now we're going to use it to sell movies," according to Tan. "The next thing goes to trying to sell bandwidth [at a] much cheaper rate than CDNs [content delivery networks]."

Also on the near horizon is the use of P2P networks as an advertising platform, said Tan.

Meanwhile, the Xbox 360 is already "one of the most successful" P2P platforms out there today, according to Microsoft's director for P2P networks. "Halo 3 is actually one of the most compelling (P2P games)," he contended.

In Halo 3, he said, the XBox 360 platform works as a "broker" to match up players in ways intended to ensure high quality of service (QoS). "Players communicate in P2P," said Tan. "P2P is actually key to the whole experience."

Xbox 360 communication between players takes place over the Xbox Live network, which has connections with Windows Live services. Microsoft also "continues to invest" in P2P technologies for Windows, Tan added. Microsoft is "letting protocols in Windows do the heavy lifting" for P2P.

Teredo was designed in 2003, and later implemented in Vista, as a novel approach for moving network traffic where packets use IPv6 protocol and addresses, across a firewall that uses an IPv4 network address translator. NAT is the most common method for any firewall to mask computers within a subnet. Each of those computers is given an IPv4 link-local address, usually beginning with the prefix 192.168.x.x.

But with Windows Server 2008, which premiered late last month, utilizing IPv6 as a default alternative addressing scheme for the first time, Vista had to be ready to support it as well. So rather than tunnel underneath the firewall, Teredo builds a kind of for-the-nonce P2P bridge over it, while still letting the NAT do the job of forwarding packets to their final IPv4 link-local destinations.

Another of the new technologies being considered for Windows 7 is given the timely name "Green P2P." It's a power management system for letting "PCs go to sleep and wake up only when addressed" over a P2P network.

Microsoft is also thinking about adding metered connections so as to reduce network "chattiness" over P2P links.

As another improvement, Microsoft is contemplating distributed hash tables (DHT), both for enterprise data centers and broad Internet use, said Tan. DHTs are aimed at supporting scalability on P2P and CDN networks to very large numbers of nodes.

Since P2P networks are decentralized by design, what appears to any one peer to be a catalog of all the accessible files in those networks are actually piecemeal composites of the pieces of shared directories from all the peers put together. When one peer goes down unexpectedly, the integrity of that entire patchwork can be jeopardized. A DHT can remedy that problem by building hash tables that contain remnant data from the entire catalog, and then broadcast those tables among multiple peers, so in the case of one peer going down, the catalog can more easily be reconstructed.

Other technologies now being contemplated for Windows 7 would help to maintain QoS and reduce network delays in media streaming delivery, according to the Microsoft exec.