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Top1. Introduction
With the extensive use of low-power devices and the emergence of various new applications, it is necessary for low-power devices to access the Internet to satisfy demands for new applications. IPv6 over Low-Power Wireless Personal Area Networks (6LoWPAN) might be an ideal solution to connecting these devices to the Internet. In 6LoWPAN, each low-power device can use the IPv6 protocol to achieve communications with the Internet.
Before 6LoWPAN can achieve correct communications with the Internet, two key issues, namely addressing and routing, must be addressed (Liu, Xu, Wu et al., 2015). Two independent 6loWPAN standards (Shelby, Chakrabarti, Nordmark et al., 2012; Winter et al., 2012) separately address these two issues. That is, 6LoWPAN first performs the standard (Shelby et al., 2012) to achieve the addressing. After the addressing is complete, 6LoWPAN fulfils the standard (Winter et al., 2012) to implement the routing. Therefore, in the standards, addressing and routing are achieved serially by two independent processes. In order to improve the performances of addressing and routing, some addressing-based routing solutions (Liu et al., 2015; Wang & Qian, 2013; Tsai & Tseng, 2012; Wang, Zhong & Zhou, 2012) are proposed. In these solutions, via the addressing process, 6LoWPAN is constructed into a special topology which is usually a tree. After the addressing process is complete, the routing can be achieved through this special topology without route discovery. Since the addressing and routing are achieved only via the addressing process, their performances are improved. However, these addressing-based routing solutions usually connect 6LoWPAN to the Internet via a single gateway and typically organize 6LoWPAN into a tree topology (Liu et al., 2015; Wang & Qian., 2013; Wang et al., 2012) where the gateway is the root, so they might suffer from the following deficiencies:
- 1.
The tree specified by the sole gateway usually has a large depth, and as a result the lengths of the routing paths along the tree are relatively large.
- 2.
The sole gateway has to forward all the messages to the Internet, so the resources of the gateway and the nodes around the gateway are excessively consumed and the links around the gateway also become congested.
- 3.
If an intermediate node fails, its descendants must rejoin the tree and be reconfigured with a new address. During the address reconfiguration process, the descendants are unable to communicate with the Internet.
- 4.
If the gateway fails, then all the nodes in the tree cannot communicate with the Internet.
Anycast is suitable for the communication paradigm in both the IPv6 network (Wang, X., 2008) and low-power networks (Kostin, Fanaeian & Al-Wattar, 2015; Khianjoom & Usaha, 2014; Ohta & Makita, 2013; Kim, Lin, Shroff et al., 2010) because it can effectively improve the communication performance. In order to overcome the above deficiencies, this paper introduces anycast to 6LoWPAN and proposes an anycast-tree addressing-based routing scheme for 6LoWPAN. This paper has the following contributions: