Question: In a 5G System, when an UPF (User Plane Function) redirects a service request to a different UPF instance using HTTP redirection with a 307 Temporary Redirect or 308 Permanent Redirect status code, how is the identity of the new UPF indicated?
Option 1: Via the `3gpp-Sbi-Producer-Id` header in the original service request.
Option 2: Through a separate DNS query for the new UPF instance's IP address.
Option 3: In the `3gpp-Sbi-Target-Nf-Id` header of the 307/308 Redirect response.
Option 4: By embedding the new UPF's ID in the URL path of the redirect location.
Explanation: When an UPF redirects a service request to another UPF instance, it uses HTTP status codes 307 (Temporary Redirect) or 308 (Permanent Redirect). To ensure seamless redirection and maintain service continuity, the identity of the target UPF must be clearly indicated. This is achieved by specifying the new UPF's ID in the `3gpp-Sbi-Target-Nf-Id` header within the redirect response itself, ensuring that the requesting entity can directly address the new UPF instance without additional lookup steps.