1. INtroduction
One of the critical issues in Next Generation Networks (NGN) development is resource management. This issue has forced clear-sighted organizations such as ITU and ETSI to propose some models and architectures for provision of resource management in NGN networks. An architecture which has been introduced by ITU-T for the sake of resource management is called RACF (Resource and Admission Control Function), whose simplified structure is indicated in Fig. 1 [1]. ETSI has also recommended a model for resource and admission control in NGN that is envisaged as an instance of ITU RACF for fixed access networks [2].