|Zigbee Alliance Aiming at IPv6 Support||| Print ||
|Written by Akiba|
|Saturday, 01 March 2008|
The Zigbee Alliance announced that they're forming an "Internet Solutions Initiative" to investigate ways of integrating IP networking into Zigbee. Translation: They're forming a new IP6 group.
Looks like they've taken notice of the work thats going on over at 6LowPAN and Adam Dunkel's Contiki/uIP project . Anyone thats familiar with the Zigbee spec knows that its almost a one to one correspondence with TCP/IP. The Zigbee NWK layer is analogous to the IP layer, the NWK routing protocol, AODV, is analogous to IP's RIP or OSPF, and the Zigbee Application Framework is analogous to the TCP layer (without the TCP state machine and the weird sequence space thing). Zigbee has endpoints, TCP has ports. Zigbee has endpoint grouping, TCP has port binding. The list goes on and on.
One of the main benefits of Zigbee is that the protocol is designed for operation over wireless networks and was basically designed to fit 802.15.4. 6LowPAN on the other hand is doing double-back-handsprings-with-a-twist to get IPv6 to fit into the 802.15.4 frames.
The problem that arises is that IP wasn't meant to be packaged into a 128 byte frame. The IPv6 header alone is a whopping 40 bytes or almost 1/3 of the frame size. If they integrate TCP, they'll have even more overhead to deal with. TCP/IP fits better into ethernet frames where the max frame size is 1580 bytes (I think). In that case, the protocol overhead is a much lower percentage of the overall traffic and they can transport larger amounts of data. In fact, that hits on an important point. TCP/IP is designed for data intensive communications. Zigbee/802.15.4 is designed with the low power/low duty cycle requirements of wireless sensor networking in mind. So thats one of the big challenges of integrating Zigbee and IP, or even IP and 802.15.4. I don't think I will need to access all of my nodes from Firefox. So would it be bad to just use a Zigbee/IP bridge or gateway at the coordinator?
p.s. I wonder how 6LowPAN and ArchRock respond to this?
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