Control-Plane and User-Plane Separation BNG Simple Control Channel Protocol

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, should requirements be expressed in the future.