6LowPAN

competing code/solutions exists:

6LoWPAN from Contiki - ongoing porting to ARM M0+ by Graeme, tried and tested with olertia Z1's and TelosB

CC1180 radio which includes sensinode's 6LoWPAN stack - proprietary low level but we could possibly live with that - the NAP socket library is certainly worth using

Libelium waspmotes - with moterunner - works OK (even at 868MHz) but we are inexperienced with the development