The move to bring IPv6 to wireless sensors networks, making them part of the next-generation Internet, got a boost this week with new products from two vendors, and an Internet group taking the next step in standardizing the protocol for these low-power networks.
Both the products and the advancing standard are adding fuel to a controversy over whether the Internet protocol suite is suitable for short-range, low-power networks, especially with a variety of other protocols, such as ZigBee, being adopted by vendors for a growing range of vendors.
Meeting in Prague, Czech Republic, earlier this week, the Internet Engineering Task Force’s IPv6 Low Power Wireless Personal Area Network working group (6LoWPAN) took another step toward a final standard.
The group’s goal is to implement IPv6 so that the protocol stock can run on small, usually battery-powered, sensor devices that are linked via low-power, short-range radios, in this case based on the IEEE 802.15.4 standard. Each node on such a network would become another IP node, directly addressable by another sensor node or by a node on another IP net.
At Monday’s meeting, the working group made three tweaks to the draft protocol. “These three items should not delay the document from progressing on the standards track, and they’re trivial [to change] for any of the companies that have already implemented it,” says Geoff Mulligan, an independent consultant and co-chairman of 6LoWPAN. Mulligan says the document is poised to enter the final stage of becoming an IETF “Internet standard.”
But vendors are already moving. Arch Rock has added IPv6 to its Primer Pack, now dubbed Primer Pack/IP, which combines an IP gateway server to connect to enterprise networks; the Arch Rock Bridge Node with a 802.15.4 wireless interface to connect to the sensor networks; six battery-powered sensor nodes; and a set of Web services and gateway server APIs. The company claims to be the first to offer IPv6, based on the emerging 6LoWPAN standard, for this class of networks.
Arch Rock has incorporated a database to collect and manage sensor data on the gateway and then synchronize it with a back-end database.
IP protocols let these devices interoperate with other IP-based networks, but also with existing gateways, with existing industrial interconnect standards, says David Culler, CTO and co-founder of Arch Rock. They can exploit existing Internet proxy architectures for authentication, VPNs and the like, and can be managed via Internet standards such as SNMP.
Primer Pack/IP is priced at $4,995. It’s nearing the end of beta testing, and will ship as early as April 2007.
Augusta Systems has added to its product a gateway appliance, called SensorPort, that’s designed to integrate an array of non-IP sensor nets into an IP infrastructure, including IPv6, and do pre-processing of sensor data on the edge of the network, before forwarding it on to other servers or applications.
SensorPort can be fitted with various wireless Interfaces, such as ZigBee or Wi-Fi, to communicate with the sensors, and has an Ethernet port to link to the enterprise LAN. “Any type of processing you can do on a PC, we can perform on SensorPort,” says Patrick Esposito, Augusta’s president and COO. The appliance can calculate average values from the data received for example, run a third-party data application, and filter the data flood from the sensors. “You’re not just streaming data to a server in the data center,” Esposito says.
SensorPort can convert non-IP data to IP, and IPv4 information to IPv6.
Augusta’s flagship product is SensorBridge, which is a set of software components and tools that plug into the Microsoft Visual Studio toolset. Software developers use these components to capture sensor data, manage and structure it, and then integrate it with back-end databases and applications, for both IPv4 and IPv6 networks.
The move to embrace IPv6 for sensors offers a lot of benefits, says David Green, vice president of R&D for Command Information, a start-up formed in 2006 to focus entirely on IPv6 networking. Typically, today’s sensor networks, including building automation controls and security devices, run proprietary protocols and software, making them difficult to integrate with IP infrastructures, he says.
“As we ‘IPv6’ these devices, we give them the ability to communicate directly with the Internet, without special gateways, or protocols,” Green says. Command Information has been working with Augusta’s original SensorBridge software components to build a range of prototype IPv6-enabled applications, such as peer-to-peer first responder nets. “The auto-discovery, peer-to-peer capability, and other features of IPv6 are ideal for this, when you’re creating a net quickly, without a lot of server infrastructure,” he says.
The new SensorPort gateway will let Command’s developers bring non-IP sensors into an IPv6 network.
“Never bet against IP,” advises Harry Forbes, senior analyst with ARC Advisory Group, a consulting and market research company. With IP in both the sensor networks and enterprise networks, integration, management and operations are simpler, he says.
“The sensor net doesn’t support any of the IP services,” Forbes says. “You have to build an embedded service inside the gateway to manage the sensor network. It’s labor intensive and it doesn’t scale well.”
Yet he doesn’t expect IPv6 to take over the industrial and manufacturing worlds any time soon. Companies like British Petroleum, for example, have invested heavily in replacing wired sensor connections with wireless -- in BP’s case, with 802.15.4. “They’ve had huge savings just from this wireless piece…so IPv6 won’t necessarily help with those applications,” Forbes says. “IPv6 is not a huge breakthrough [in these areas] at this time, but it certainly is one of the more interesting things we’ve see in this space for a while.”
But it’s not a trivial thing. The 6LoWPAn group had to define a new, more efficient header that could work with different types of sensor networks, from simple to complex. It borrowed the “stacked header” design from IPv6, which allows additional headers to be defined if, and when, they are needed. A second major issue was how to compress the IPv6 header to fit efficiently into the 802.15.4 frame. The group devised a technique that packs the normal 40 bytes of a full IPv6 packet into just 1 byte for traffic between personal-area networks.
Finally, the 6LoWPAN protocol works with any mesh network, from ZigBee to open protocols such as the Ad hoc On Demand Distance Vector and the Optimized Link State Routing Protocol, both for mobile, ad hoc networks.
“The 6LoWPAN effort has a long way to go,” says Bob Heile, Chairman of the ZigBee Alliance, an industry group of more than 200 companies focused on running the ZigBee protocol over 802.14.5. “They’re starting from scratch; they have to look at discovery techniques and all the rest.”
ZigBee addresses all that today, Heile says. “[The idea of] ‘IP in everything’ is a religious war,” he says. “It’s not something we didn’t think about. We looked at it carefully. Putting an IP stack in every $2 switch was not the most cost-effective way to go.”
“TCP/IP gives you interoperability and compatibility,” says Dave Retz, president of Comware International, a developer of Internet and Web software. Retz was one of the original ARPANET engineers and has been involved in the Internet since 1969. “I’ve really come to appreciate the ubiquity of TCP/IP,” he says.
Comware works with the Arch Rock platform and has just got the beta version of Primer Pack/IP. “Those little [sensor] motes are running IP,” Retz says. “They have SNMP, NetStat, Echo, all the Telnet-like functions are running on those motes. You can grab data directly from them.”
“The IP standard will accelerate the sensor network market,” Retz says.
With its early implementation of 6LoWPAN, these nodes now interoperate with existing IP-based networks and, via gateways, with ZigBee and other sensors networks, he says.