Wireless Sensor Network (WSN) is an essential part and key enabler of the Internet of Things (IoT), where hundreds or thousands of small smart sensing or control nodes are interconnected to transmit sensing/monitoring information or control instructions. In order to implement sensing/monitoring or control services at a large scale with seamless connection to the Internet, IPv6 would be the best solution due to its many advantages including its highly scalable address scheme, stronger security, and full Internet compliance. Therefore, IPv6 over WSN is getting more and more research and development (R&D) attention from both industry and academia.