Section: N.2.2 Redundant transmission on N3/N9 interfaces
Content: If the user data redundancy is fulfilled by means of two duplicated N3 tunnels, the redundant packets will be transferred between UPF and RAN via two independent N3 tunnels, which are associated with a single PDU Session, over different transport layer path to enhance the reliability of service. Figure N.2.2-1: Redundant transmission with two N3 tunnels between the UPF and a single NG-RAN node In order to protect the redundant traffic on the N3 reference point, the current mechanism defined in clause 9.3 of the present document shall be reused. The added path for redundancy shall provide equal level of security compared to single path. In case two N9 tunnels are involved to fulfil the redundancy for one NG-RAN, the security mechanism defined in clause 9.9 shall be used for protecting the redundant data transferring via two N9 tunnels as described above.