A mechanism by which handoff delay can be minimized while not compromising the IMS/MMD security and also protecting the media if required by certain applications is presented. Methods for mitigating delay during SA re-association and mitigating the IPSec tunnel overhead for signaling and media at the Mobile Node are given. In one embodiment, SA keys can be transferred from the old P-CSCF to new P-CSCF, enabling the establishment of SAs before Mobile Node physically moves to the new subnet in a network. Proactive handover is used. In another embodiment, SA keys are transferred from S-CSCF to new P-CSCF. In this case, the SA keys are transferred to the new P-CSCF by S-CSCF through a context transfer mechanism well in advance so that SAs may be established before Mobile Node physically moves to new subnet. In another embodiment, methods for mitigating IPSec tunnel overhead are presented.