Question: Upon receiving a PFCP Session Establishment Request with rules that the UP Function cannot fully store or apply, but both CP and UP Functions support the PSUCC feature, how should the UP Function proceed?
Option 1: Store and apply as many rules as possible, return a partial acceptance response with the Rule ID of the first failed rule.
Option 2: Discard all received rules, do not create any PFCP session context, and return an error cause value with the Rule ID of the first failed rule.
Option 3: Request the CP Function to resend the rules after a specified timeout, without returning any immediate response.
Option 4: Automatically trigger a PFCP Association Update procedure to renegotiate supported features.
Explanation: According to the described UP Function behavior, when both CP and UP Functions support PSUCC, the UP Function should attempt to partially accept the request if possible. This involves storing and applying as many rules as it can from the PFCP Session Establishment Request, while returning a response indicating partial acceptance with details of the first error-causing rule (Rule ID), maximizing session utility within the UP Function's capabilities.