Hu, S., Eastlake, D., Qin, F., Chua, T., and D. Huang, "The China Mobile, Huawei, and ZTE Broadband Network Gateway (BNG) Simple Control and User Plane Separation Protocol (S-CUSP)", RFC 8772, DOI 10.17487/RFC8772, May 2020, <https://www.rfc-editor.org/info/rfc8772>.