**1. Introduction**

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The "Internet of Things" semantically means ''a world-wide network of interconnected ob‐ jects uniquely addressable, based on standard communication protocols" [1]. The vision de‐ scribes a world that enables physical objects to act as nodes in a networked physical world [2]. The terms ''Internet of Things" can be attributed to The Auto-ID Labs, a world-wide net‐ work of academic research laboratories in the field of networked RFID and emerging sens‐ ing technologies [2]. Together with EPCglobal®, these institutions have been architecting the Internet of Thing since their establishment. Their focus has primarily been on the develop‐ ment of the Electronic Product Code™ (EPC) to support the wide-spread use of RFID in modern, global trading networks, and to create an industry-driven set of global standards for the EPCglobal Network.

EPCglobal Network was created for "traditional" low-cost tags [3]. The main functionali‐ ty of the EPCglobal Network is to provide data assigned to a specific tag, so that each RFID read event can be stored in a database and applications can be built on this data. Since tags were not originally considered to carry or compute additional data, the EPC‐ global Network does not traditionally provide a mechanism to address remote tags from networked applications.

The data flow in these networks works from tags via readers to a couple of networked serv‐ ers. Passive, low-cost RFID tags are widely available and the EPCglobal Network was de‐ fined to support open-loop supply chain applications. Basically, this is accomplished by allowing servers to communicate over the Internet. Although RFID technology is quite ac‐ cepted in closed-loop applications, the evolution towards open-loop systems using the EPC‐ global Network with distributed databases did not take place as predicted due to problems in the access control layer of such systems.

© 2013 Jensen and Jacobsen; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Jensen and Jacobsen; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

RFID-sensor networks are an emerging part of the Internet of Things [5]. These devices com‐ bine sensing capabilities with an RFID interface that allow the retrieval of sensed data. In fact, they can cooperate with RFID systems to better track the status of things e.g., their loca‐ tion, temperature, movements, etc. A sensor-enabled RFID tag (also known as sensor-tags) is an RFID tag which contains one or more sensors to monitor some physical parameter (e.g., temperature) but also contains the same identification function as a "normal" RFID tag does. This kind of sensor tag may fall into class 2, class 3 or class 4 in EPCglobal's tag classi‐ fication [3]. A fully passive, class 2 sensor-tag can measure physical parameters, i.e., use sen‐ sors, only when powered by a reader. In contrast, class 3 tags are battery assisted. They can work independently of the reader and can be suitable for RFID-sensor networks.

themselves and need a separate power source. A solution where the tags are modified to hold the IPv6 stack on them is discussed by Rahman et al. [4]. The tags EPC, which is its identity, would then be made into a part of the tags IPv6 address due to the design of the tags proposed. This makes these tags too expensive for integration into the Internet of Things since the price of the tags could easily exceed the value of the "things" themselves.

Integrating RFID with IP Host Identities http://dx.doi.org/10.5772/53525 113

Barish et al. [13], describes a somewhat similar setup than the one proposed here. In their approach, a global address manager is used to keep track of tags. The basic idea is that an application sends the EPC to a global server along with the IP address that the tag has been associated with. When a corresponding node wants to communicate with the tagged object, it contacts the last known address. If the tag is in the field of the reader the connection is established and communication can begin. If the tag is not present at the location the request is redirected to the global address server that returns the tag's present address or just redi‐ rects the request to the correct address. In contrast to the proposed solution by Barish et al. [13], the approach described here does not include extra nodes in the network to construct network addresses but adds functionality to the RFID readers residing at the network edge.

Xu et al. [25] proposed a general address mapping scheme based on a proprietary protocol named General Identity Protocol (GIP). The scheme takes all existing RFID systems into ac‐ count, and allows heterogeneous RFID systems to interwork over the Internet. This is ac‐ complished by mapping RFID tag identifiers to IPv6 addresses, constructing a GIP message with details of the RFID systems in use, and finally encapsulating the message in IPv6 and routing the packet over the Internet. This chapter describes a solution that minimizes the

There are a couple of ways to interconnect objects by using RFID with IPv6 [6]. One solution would be to give the tags the ability to communicate via the Internet. The communication can be both reader-initiated and tag-initiated. The latter requires specific tags that require electrical and processing power to be available in the tag such as e.g., EPC class 3 tags. Most of the computational work takes place in the tags, i.e., the tag is reachable and visible as an

Passive RFID tags, such as EPC class 2 tags, do not have the possibility to power a network protocol stack and therefore a network address cannot be directly assigned to the tag's mi‐ crochip. However, the passive tag can be represented by virtual interfaces residing in the

RFID systems are composed of one or more readers and several electronic tags. Tags are characterized by a unique identifier that takes the form as a binary number. They are ap‐ plied to objects and even persons or animals as implants. From a physical point of view, an

IPv6 connected host as long as it is within the electric field of a reader.

need for control protocols.

**3. Enabling technologies**

reader interrogating the tag.

**3.1. Radio Frequency Identification (RFID)**

In this chapter, we will discuss different ways to achieve the Internet of Things vision by internetworking passive RFID tags over IPv6. The chapter is organized as follows: Section 2 presents related works and discusses the novelty of the work presented here. Section 3 intro‐ duces the key technologies for the convergence of RFID and Internet namespaces and to provide an address mapping needed to internetwork passive RFID tags. In Section 4, some common examples of RFID usage are given and discussed in the context of globally net‐ worked tags. Subsequently, Section 5 introduces a testbed built to study the interconnection of passive RFID tags over IPv6. The different strategies that can be used for integrating RFID with IPv6 are discussed in Section 6 and this discussion is followed by mobility considera‐ tions in Section 7. Finally, Section 8 concludes the discussion and outlines anticipated future work in this area.
