On Some Fundamental Properties of P2P Push/Pull Protocols

The peer-to-peer communication paradigm is changing the way the Internet works, and the perspective network and service providers are looking at the telecommunication business. P2P applications and networks are taking foot by the day, and new systems are proposed continuously with ever novel features and better performances. In spite of attention and success, however, there is still a lack of fundamental analysis and understanding of the elementary properties of these systems. In this paper we consider a class of P2P protocols suitable both for content delivery (file-based communications) and for high-bandwidth media streaming like video and TV, and explore its fundamental properties. The class considered is known as mesh-based swarming push-pull systems or interleave protocols. They split the content in pieces and alternate continuously two phases: One where the peer pushes a piece to another peer to percolate information in the system, and the other when it pulls a piece trying to retrieve missing information. We compare synchronous and asynchronous models and explore the impact of protocols parameters, such as the dimension of the active neighborhood, trying to identify the efficiency of these very simple protocols in different scenarios, gaining insight to design the next protocol generation with performance and efficiency in mind.