The Desktop Grid technology consists mainly in exploiting personal computer, geographically dispersed, to deliver massive compute power to investigate complex and demanding problems in a variety of different scientific fields. However, as resources number increases, the need for scalability and decentralization becomes more and more essential. Since such properties are exhibited by Peer-to-Peer systems, we aim at using them to create a decentralized desktop grid middleware. Nevertheless, in order to judge the efficiency of such P2P library, an experimental performance evaluation of the provided functionalities is unavoidable. Very few analysis of this kind have been reported, as most evaluations are limited to complexity analysis and to simulations. Such experimental analysis are important, especially when using P2P tools in grid computing context, when applications may have precise efficiency requirement. In this paper, we focus on three libraries: Bonjour, Avahi and Pastry, which provide generic API intended to serve as basis for specialized P2P applications. We perform a performance evaluation of the scalability and their capacity to register and browse an important number of services over 300 hosts in Grid'5000 for recent versions of Pastry, Avahi and Bonjour. We provide detailed analysis explaining the behavior of each library related to two criteria: the elapsed time for registration services and the needed time to discover services. Our aim is to choose the most adequate protocol for creating a decentralized middleware for desktop grid.