An interactive service- oriented P2P networks architecture (ISPNA) is proposed in this paper.  Based on the further analysis on the service demand of distributed P2P applications,  and considering the characteristics of P2P networks such as loose-coupled,  self-organizing,  and scalability,  the key availability enhancing issues of P2P networks are resolved by several different layers in ISPNA,  of which mutual relations are to analyzed.  From the architecture point of view,  to synthetically take into account the omnifarious factors that affect the availability of structure P2P networks and to analyze the causes of their formation should be helpful to put the questions in right perspective.