Section: 13.3.3 Authentication and authorization between SEPP and network functions
Content: NOTE 1: This clause also describes authentication and authorization between SEPP and NRF, because the NRF is a network function. Authentication between SEPP and network functions within one PLMN shall use one of the following methods: - If the PLMN uses protection at the transport layer, authentication provided by the transport layer protection solution shall be used for authentication between SEPP and NFs. - If the PLMN does not use protection at the transport layer, authentication between SEPP and NFs within one PLMN may be implicit by NDS/IP or physical security (see clause 13.1). A network function and the SEPP shall mutually authenticate before the SEPP forwards messages sent by the network function to network functions in other PLMN, and before the SEPP forwards messages sent by other network functions in other PLMN to the network function.