[IEEE 2012 Seventh International Conference on Broadband and Wireless Computing, Communication and Applications (BWCCA) - Victoria, BC, Canada (2012.11.12-2012.11.14)] 2012 Seventh International Conference on Broadband, Wireless Computing, Communication and Applications - The IPSec Security Problems and a Cross-layer Security Mechanism for PMIPv6 Handover when an IPSec Security Association is Established on an L2 Direct Link