Research of Neighbor Discovery for IPv6 over Low- Power Wireless Personal Area Networks Bingqing Luo; Suning Tang; Zhixin Sun Key Laboratory of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications, Nanjing, China Email: sunzx@njupt.edu.cn Abstract—The Ipv6 neighbor discovery protocol is unable to meet the networking and address configuration requirements of the nodes in the wireless sensor network (WSN). To address this problem, the 6lowpan network architecture is presented in this paper, and based on the architecture, a method for configuring addresses of the 6lowpan nodes and a basic process for interaction during neighbor discovery are proposed. A context management and distributing strategy is also proposed to expanded 6lowpan domain, providing an approach to the standard protocol RFC6775. Simulation results show that the proposed 6lowpan neighbor discovery protocol is highly feasible and effective. Keywords-6LoWPAN; neighbor discovery; context; header compression; address configuration I. I NTRODUCTION The IPv6 in Low-Power Wireless Personal Area Networks (6LoWPAN) [1] is an IPv6-based low-speed wireless personal area network standard. The 6LoWPAN Working Group was created by the Internet Engineering Task Force (IETF) Working Groups to standardize an adaptation layer on top of IEEE 802.15.4 [2] physical (PHY) layer for IPv6 network [3]. The adaptation layer provides header compression and packet fragmentation/reassembly, enabling IPv6 packets to be carried on the WSN. The 6LoWPAN Neighbor Discovery (6LoWPAN-nd) protocol is an indispensable part of the 6LoWPAN standard. It specifies the node address configuration methods, networking process and the neighboring route discovery process. But the standard IPv6 neighbor discovery protocol is unsuited for low- power wireless network and cannot support the operation of the adaptation layer in 6LoWPAN. Therefore, many works have been done to simplify the IPv6 neighbor discovery protocol and incorporate necessary functions [4, 5]. IETF released the latest neighbor discovery protocol RFC6775 [6] in 2012. However, the 6lowpan-nd protocol proposed by Shelby et al. failed to provide detailed schemes for command overhead control, node registration, node acknowledgement and the support for the 6LoWPAN wireless sensor network with multiple border routers. In addition to the 6LoWPAN network architecture, this paper proposes a neighbor discovery protocol for 6LoWPAN, including the design of the address configuration method, the basic protocol for 6LoWPAN neighbor discovery and interaction, and the enhanced context distribution and synchronization strategy for the expanded 6LoWAPN domain. Finally, the 6LoWPAN and neighbor discovery protocols in the kernel of Contiki are improved via Cooja, achieving communication and networking between the 6LoWPAN node and the gateway. The test demonstrates the feasibility and effectiveness of the proposed neighbor discovery protocol. II. DESIGN OF THE 6LOWPAN NETWORK ARCHITECTURE Fig.1 shows the 6LoWPAN network architecture consisting of sensor nodes, routers, 6LoWPAN border routers (6LBRs), resource management platform and several Internet of Things applications. On the sensing layer, the architecture classifies the device nodes with heterogeneous codes or protocols using the virtual domain classification method. Unlike what the Internet gateway means, 6LBRs is on the network layer, meaning that it needs to forward the packets on the network layer and adapt to different sensing networks by performing address configuration and conversion. Due to the diversity, heterogeneity and large number of terminals in the Internet of Things environment, the Internet of Things resource management platform locates and acquires resources effectively via terminal resource addrress. Figure 1 6LoWPAN network architecture WK ($, ,QWHUQDWLRQDO &RQIHUHQFH RQ +HWHURJHQHRXV 1HWZRUNLQJ IRU 4XDOLW\ 5HOLDELOLW\ 6HFXULW\ DQG 5REXVWQHVV 46+,1(   k  ,&67 '2, HDL 