6LoWPAN Fragment Forwarding

Low-power wireless technologies have been applied to industrial fields not only to monitor facilities but also to control them. There is a legitimate requirement to integrate low-power wireless networks with existing IP-enabled networks such as the Internet. The 6LoWPAN standard makes this happen easily by enabling low-power wireless networks to transport IPv6 packets. A challenge is that an IPv6 packet might not fit in a link-layer frame. The answer is fragmentation: the IPv6 packet is cut into fragments, each fitting in a frame. In a typical implementation, the IPv6 packet is fragmented and reassembled at every hop. Such per-hop reassembly causes low endto- end reliability and high end-to-end latency. This article presents a new implementation technique that results in fragment forwarding without changing any of the standards. Simulation results show how, when going from per-hop reassembly to fragment forwarding, end-to-end reliability goes from 40 percent to 100 percent, memory requirements go from 1280 B to 160 B, and end-to-end latency is halved.