A Broadband Network Gateway (BNG) in a fixed wireline access network is an
  Ethernet-centric IP edge router and the aggregation point for subscriber
  traffic. Control and User Plane Separation (CUPS) for such a BNG improves
  flexibility and scalability but requires various communication between the
  User Plane (UP) and the Control Plane (CP).  China Mobile, Huawei
  Technologies, and ZTE have developed a simple CUPS control channel protocol
  to support such communication: the
  Simple Control and User Plane Separation Protocol (S-CUSP). S-CUSP is
  defined in this document.

     
  This document is not an IETF standard and does not have IETF
  consensus.  S-CUSP is presented here to make its specification
  conveniently available to the Internet community to enable diagnosis
  and interoperability.