Historically, the role of telecommunication has evolved from that of plain information exchange to a multi-service field, with "Value Added Services (VAS)" integrated with various discrete networks like PSTN, PLMN, Internet Backbone etc. However, with decreasing average revenue per user and increasing demand for VAS has become a compelling reason for the service providers to think of the convergence of these parallel networks into a single core network with service layers separated from network layer. Next-generation networking is such a convergence concept which according to ITU-T is: