The Design And Implementation Of Routing And Neighbor Discovery Based On 6LoWPAN

The Internet of Thing is considered to be the next big opportunity, and challege,for the Internet engineering community, user of technolopy,companies and society as a whole. It involves connecting embedded devices such as sensors, home appliances and even toys to Internet Protocol(IP) based networks. The number of IP-enabled embedded devices is increasing rapidly, and although hard to estimate,will surely outnumber the number of personal computers(PCs) and servers in the future. IPv6 protocol solve the problem of IPv4 address depletion. It is possible that a large amount of equipment connect to a IP-based network. 6LoWPAN protocol based on IEEE802.15.4 protocol realizes the IPv6 protocol. 6LoWPAN has the potential of working in low-power consumption, it is suitable for application to the handheld devices and apparatus. Built-in AES-128 is strong security guarantee. 6LoWPAN removes the complex gateway and realizes connection with external networks. 6LoWPAN also invented a compression method of IP header. It only sends the essential information of the IPv6 header. Mostly,40 bytes of IPv6 hesder can be compressed into 2 bytes. So the compression method increases the efficiency of data transmission and also reduces the network payload. Therefor 6LoWPAN is the future trend because of its low rate, low-power features.MAC layer and physical layer in the paper use the IEEE 802.15.4 standard. The standard is provided low rate, low power and low-cost features for wireless sensor networks. IEEE 802.15.4 protocol is maded by IEEE 802.15.4 working group. The standard defines standard of connection and communication between devices in wireless personal area network (PAN). The standard uses CSMA/CA to access, and supports for star topology and peer to peer topology. All communications are built on the basis of super-frame. PAN coordinator resolves the time interval of accessing. When need to connect some advanced network, which will be completed by the PAN coordinator. The task in this article is that builds a Adaptation Layer(6LoWPAN) between the network layer(IPv6) and the MAC layer(IEEE802.15.4). he following description is the main function of adaptation layer. First, it is header compression for IPv6 header, TCP header, UDP header, ICMPv6 header. Header compression can reduces the proportion of message header in the total frames, thereby reduces the pressure on network load. Second, it is fragmentation and reassembly of a IPv6 packet. Since the minimum MTU of IPv6 protocol is 1280 bytes, while the maximum length of frame in MAC layer is 127 bytes, so in order to transfer large data, adaptation must defines fragmentation and reassembly. Third, multicast must be defined. Many functions of neighbor discover are used to multicast. Fourth, it is the address allocation and build networks. The final function is to complete the adaptation layer routing.Finally, using Cooja simulation software test the designr for verifying the correctness and feasibility of the design.