The p2pd toolkit is an implementation of The SPP architecture, which is described and analyzed in detail in Evaluation of a comprehensive P2P video-on-demand streaming system and The SPP architecture -- A system for interactive VoD streaming.
The SPP architecture was designed to be a scalable solution for commercial VoD distribution, with support for interactivity, encrypted video, caching, and node clustering. With the exception of encrypted video, the current p2pd implementation includes all the functionality described in the documents above.
It is possible to use p2pd to construct a CDN for HTTP-based VoD streaming (with no P2P component), or to build an integrated low-cost CDN-like system using SPP. For more details, see the usage examples in the documentation page.
The p2pd implementation is distributed as source code under a BSD-like license. It currently runs on UNIX/Linux systems only.