China Mobile Futurewei Technologies Huawei Technologies China Mobile China Mobile Singapore Telecommunications ZTE This document specifies the Simple Control Plane (CP) and User Plane (UP) Separation Broadband Network Gateway (BNG) control channel Protocol (S-CUSP) for communications between a CP and a UP. S-CUSP is designed to be flexible and extensible so as to easily allow for the addition of further messages and data items to meet future requirements.