What is the Internet of Things in practice? Maybe the simplest definition is that the Internet of Things encompasses all the embedded devices and networks that are natively IP-enabled and Internet-connected, along with the Internet services monitoring and controlling those devices. Figure 1.2 shows an illustration of the Internet of Things vision.
Figure 1.2 The Internet of Things vision.
Today's Internet is made up of a core Internet of backbone routers and servers, including millions of nodes (any kind of network device) in total. The core Internet changes rarely and has extremely high capacity. The vast majority of today's Internet nodes are in what is sometimes called the fringe Internet. The fringe Internet includes all the personal computers, laptops and local network infrastructure connected to the Internet. This fringe changes rapidly, and is estimated to have up to a billion nodes. In 2008 it was estimated that the Internet had approximately 1.4 billion regular users, and Google announced that over a trillion unique URLs existed in their search indexes. The growth of the fringe is dependent on the number of Internet users and the personal devices used by them.
The Internet of Things, sometimes referred to as the embedded fringe, is the biggest challenge and opportunity for the Internet today. It is made up of the IP-enabled embedded devices connected to the Internet, including sensors, machines, active positioning tags, radio-frequency identification (RFID) readers and building automation equipment to name but a few. The exact size of the Internet of Things is hard to estimate, as its growth is not dependent on human users. It is assumed that the Internet of Things will soon exceed the rest of the Internet in size (number of nodes) and will continue growing at a rapid rate.
The long-term potential size of the Internet of Things is in trillions of devices. The greatest growth potential in the future comes from embedded, low-power, wireless devices and networks that until now have not been IP-enabled – the Wireless Embedded Internet. In 2008 the IP Smart Objects (IPSO) Alliance [IPSO] was formed by industry leaders to promote the use of Internet protocols by smart objects and the Internet of Things through marketing, education and interoperability.
The Wireless Embedded Internet is a subset of the Internet of Things, and the main subject of this book. We define the Wireless Embedded Internet to include resource-limited embedded devices, often battery powered, connected by low-power, low-bandwidth wireless networks to the Internet. 6LoWPAN was developed to enable theWireless Embedded Internet by simplifying IPv6 functionality, defining very compact header formats and taking the nature of wireless networks into account [6LoWPAN].