All radio access technologies can not ensure that the Previous mobile access gateway (PMAG) can retrieve the identifier of the New access point (N-AP-ID) as required by the current predictive PFMIPv6. Neither can they ensure that the New MAG (NMAG) can obtain the identifier of the Previous access point (P-AP-ID) as required by the current reactive PFMIPv6. To tackle this problem, a network layer mechanism perceiving AP-ID for PFMIPv6 is proposed. It employs API for the Mobile node (MN) network layer to acquire the information of AP-ID and reuses the existing ICMP messages to convey the information to MAG. Minimum required extension of messages is defined and detailed message sequence charts are elaborated for both predictive and reactive PMIPv6. Technical features and performance analysis are provided. Finally it is concluded that the proposed mechanism is future proof in that it can be used in conjunction with any possible radio access technologies.