Q: Can I deploy slice-specific AMF or say is AMF selection by slice supported?
A: Yes. During NG setup procedure, AMF must convey a list of supported slices to gNB. When AMF selection takes place, gNB may (or may not) exploit this information and select an AMF which is better suited.
Q: in 5GS, can a GBR flow be a default QoS flow?
A: Yes, but it is not recommended. When EPS interworking is required, this PDU session is unlikely to be transferred to EPS successfully. In EPS, a GBR bearer must be a dedicated bearer. A dedicated bearer must be linked to a default bearer. Consequently, the transfer is not supported.
Q: What is the security mechanism of Sx/N4 interface?
A: In a sense, there is none. Of course, a PFCF node may implement an allowed list or disallowed list that screens the peer it would like to talk with. However, this approach does not guarantee the integrity and the confidentiality. So it is not an ideal approach.
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