Introduction
With energy costs on the rise and "green" mandates moving from discussion to public policy, companies are being forced to find better and more efficient ways to manage the buildings they own or occupy. Because rewiring an existing building is costly and often impractical, wireless sensor networks (WSNs) are growing in popularity. WSNs are energy-efficient and provide the ability to monitor places and things that are difficult to instrument. With WSN technology building managers can now know the exact temperature or humidity levels anywhere in a space and then fine-tune energy consumption as needed.

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Some of the WSN solutions being proposed are based on proprietary or ad-hoc networking technologies, while others are built around open standards. Users are increasingly looking to the standards-based solutions because they are far easier to scale, provide the best long-term investment protection, and offer the greatest flexibility in maintenance and management.

Of course, the most open and ubiquitous networking standard of all is the Internet Protocol (IP). But until recently, the use of IP on wireless embedded networks was not considered viable, because IP was deemed too "big" to operate on microcontrollers and low-power links – notably on the IEEE 802.15.4 radio link. The emergence of the IETF 6LoWPAN (RFC 4944) standard for IP communication over low-power radio has changed all that. This low-power wireless IP option offers a new set of longevity, security and ease-of-integration tradeoffs that make it a superior alternative to existing options.

The Need for an IP Alternative
Instrumentation manufacturers have repeatedly grappled with questions of how and when to use IP-based interconnects in place of their more traditional, often proprietary, industrial counterparts. In its favor, IP offers widespread commercial adoption, rapid development cycles and broad interoperability. Ethernet led the way as an alternative to RS485 and other multi-drop busses; and many industrial standards, including BACNet, LonTalk, CIP and SCADA, introduced an “IP option” using either TCP/IP or UDP/IP over Ethernet.

The completion last year of the IETF 6LoWPAN standard for IPv6 communication over 802.15.4 extends these same communication capabilities beyond handhelds to geographically dispersed low-power devices whose battery power must last for months or even years. To be competitive with more limited link-specific protocols, 6LoWPAN utilizes a pay-only-for-what-you-use header-compression scheme. Its built-in support for AES-128 encryption offers the basis for robust authentication and security. And, through direct integration with IP routers, it can take advantage of advanced network security schemes rather than depending on those provided by ad hoc gateways.

Why the Internet Architecture Works
The Internet architecture is defined in layers, with IP being the middle layer that forms a “narrow waist,” allowing diverse applications above to utilize a variety of communication links below in a common, link-independent fashion. Software is highly leveraged, because it is built on TCP/IP or UDP/IP data transports, regardless of the particular physical devices underneath. IP allows different kinds of links to be connected together as a single network, with routers steering each message to its desired destination, crossing different kinds of links along the way. This versatility and independence is one of the primary reasons IP continues to be relevant and pervasive more than 20 years after its initial specification. This has particular significance to anyone making long-term infrastructure choices.

The Many Advantages of IP* for an Automated Building Solution

1. IP is an open standard. The Internet Engineering Task Force (IETF) is the open recognized International Standards Organization (ISO) chartered with standardizing the IP protocol. The IETF was formed in 1986 and is organized into working groups, each with a specific charter and set of milestones. Two working groups are focusing on the use of IP protocols in sensor networks: 6loWPAN (already an approved standard) and ROLL, whose working group is addressing Routing Over Low-power and Lossy Networks).

2. IP is Flexible. IP is used everywhere for a broad set of applications. It provides a flexible, layered architecture that allows for future innovation as solutions and applications evolve. IP is supported by virtually every modern device, from high-end servers to cell phones and low-cost embedded devices.

3. IP is Everywhere. IP is available in most, if not all, operating systems for general-purpose computers and servers. Both commercially licensed and open-source implementations are generally available and most, if not all, networks provide IP access.

4. IP is Scalable. With the global Internet, IP has proven itself to be inherently scalable. No other networking technology has ever been deployed and tested at such an immense scale and with such a large number of devices. The next generation Internet Protocol, IPv6, expands the address space of IP to 2^128. Such a large address space has been said to be enough to provide every grain of sand on the planet with an IP address.

5. IP is Manageable. Management in IP networks is done with a suite of well-understood network management protocols and mechanisms. Leveraging existing standards and management techniques, IP does not need to reinvent the wheel for wireless sensor network applications.

6. IP is time-tested. The IP standard has existed for nearly 30 years and, because IP forms the basis of the Internet, will continue to exist into the foreseeable future. Furthermore, there is a large and experienced pool of developers, administrators, architects, and other IT workers that know IP and have been working with it for years.

7. IP is End-to-End. IP provides end-to-end communication between devices, without the need of protocol translation gateways sitting in between. Gateways are typically complex to design, manage, and deploy. With the success of today’s global Internet, IP's end-to-end architecture has proven itself scalable, stable, and efficient.

IP-based Wireless Sensor products already shipping
Last year, Arch Rock announced the first commercial implementation of the IETF 6LoWPAN standard, which allowed users to create pilot WSNs that run native IP end-to-end, taking the IP protocols beyond their previous boundary at the WSN gateway and out to individual sensor nodes. For the first time, sensor nodes were given the ability to communicate directly with other IP devices, whether those devices were wired or wireless, local or across the Internet, on Ethernet, WiFi, 6LoWPAN or other types of network, and regardless of vendor. 6LoWPAN is a key component of Arch Rock's PhyNet™, the first IP-based WSN to address large-scale enterprise applications, letting users centrally manage collections of those WSNs as an integral part of the enterprise IP infrastructure. PhyNet utilizes a tiered WSN architecture that eliminates the need to co-locate individual sensor networks with the server-based functions that control them by placing a scalable internetworking tier between them. Sensor applications can now reside half a world away, across a corporate campus or in the next room, communicating with any number of WSNs across local-area or wide-area IP networks.

The Industry Converges
In September 2008, a group of leading technology vendors and users formed the IP for Smart Objects (IPSO) Alliance, whose goal is promoting IP as the networking technology best suited for connecting sensor- and actuator-equipped or "smart" objects and delivering information gathered by those objects.

Smart objects are objects in the physical world that – typically with the help of embedded devices – transmit information about their condition or environment (e.g., temperature, light, motion, health status) to locations where the information can be analyzed, correlated with other data and acted upon. Applications range from automated and energy-efficient homes and office buildings, factory equipment maintenance and asset tracking to hospital patient monitoring and safety and compliance assurance.

[an error occurred while processing this directive] Intended to complement the efforts of entities such as the Internet Engineering Task Force (IETF) and the Institute of Electrical and Electronics Engineers (IEEE), which develop and ratify technical standards in the Internet community, the IPSO Alliance will perform interoperability tests, document the use of new IP-based technologies, conduct marketing activities and serve as an information repository for users seeking to understand the role of IP in networks of physical objects. The Alliance seeks to advocate how networks of objects of all types have the potential to be converged onto IP.

Conclusion
With the continued interest and investment in more energy-efficient buildings, the time is right to consider a wireless sensor networking solution to give you greater visibility into your building or space. Furthermore, with the addition of an IP-based solution, integrating these networks into an existing infrastructure is made even easier.

*IP for Smart Objects: Internet Protocol for Smart Objects (IPSO) Alliance White paper #1
Adam Dunkels, PhD, Senior scientist, Swedish Institute of Computer
Science, JP Vasseur, Distinguished Engineer, Cisco Systems, September 2008.

About the Author

Brian Bohlig, Vice President of Marketing, Arch Rock Corporation

Brian Bohlig is responsible for all aspects of marketing at Arch Rock. Prior to Arch Rock, Bohlig was Director of Corporate Marketing at VMware, where he led the company's outbound marketing efforts and was responsible for the creation of VMworld, the industry's largest virtualization conference. While at VMware, Bohlig also served as Director of Workstation Product Management, leading the product planning and go-to-market strategy for the company's award-winning workstation product line. Prior to VMware, he held a number of senior roles in product management, business development and operations at Corio and Sun Microsystems. Bohlig began his career as an investment banker at Montgomery Securities. He holds a BA degree from Dartmouth College and an MBA from the Kellogg School of Management at Northwestern University.

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