부산대학교 도서관

IETF IP WAVE Working Group proposes a vehicular mobility management scheme with a shared-prefix model that multiple RSUs share a common prefix. When using a shared-prefix model, a WAVE wireless interface on a vehicle does not need to reconfigure its IPv6 address even if its serving RSU is changed to another RSU in the same prefix domain. We had proposed a vehicular mobility management scheme for a shared prefix model over IEEE WAVE IPv6 networks. However, this still has some weaknesses. Firstly, the workload of an ingress gateway of the WAVE access network increases since it handles all downlink traffic with destination addresses with a shared prefix and all control messages generated by the vehicles served by RSUs in the shared prefix domain. Secondly, an ingress gateway and RSUs in the same prefix domain store similar vehicle information of vehicles in its domain. It increases the number of control messages and the amount of vehicle information to be stored. Lastly, IPv6 address conversion is required at the ingress gateway to forward a message to the current serving RSU of the destination vehicle of the packet. If these weaknesses occur, the processing speed of the ingress gateway will slow down as the workload of the ingress gateway increases. In addition, the memory usage will be wasted because the similar vehicle information is stored in duplicate in RSUs and an ingress gateway. To mitigate these weaknesses, we propose a SDN-based vehicular mobility management scheme. The scheme uses the SDN concept to separate the control plane and data plane. Since all control messages are handled by the SDN controller, the workload of the ingress gateway is reduced. It also makes control messages between RSUs and the ingress gateway unnecessary. The SDN controller centrally stores all vehicle information, so the ingress gateway and RSU no longer need to store vehicle information. The amount of the storage at the SDN controller are also reduced by eliminating the duplicated information at vehicle information of the ingress and the RSUs. Finally, switches in the SDN network may forward packets using SDN flow rules identified by their link-layer addresses. Destination IPv6 address conversion of packets to use the standard IPv6 forwarding mechanism at the ingress gateway and RSUs is unnecessary.