lowpan devices are an IPv6 virtual interface on top of a 6loPAN (wpan) device. The lowpan interface takes care of fragmentation, protocol handling,
The project is called linux-wpan (zigbee is avoided for TM reasons and because it’s more than zigbee). A rework is in progress to give it a netlink framework (nl802154). Crypto layer is ongoing and also the frame parsing and creation is only partially implemented (only data). The new framework cherry-picks the good things from the WLAN stack. Default interface naming: wpan#; interface type registration: node, monitor, coordinator (todo); iwpan userspace tool with same commands as iw, which uses the netlink framework nl802154; soft-MAC implementation cfg802154. Copying ideas from 802.11 is still ongoing.
nl802154 framework was introduced because of familiarity for WLAN users; before there was a custom netlink interface. Old interface still needs to be removed.
Next Header Compression (NHC) feature: allows to remove the info from headers when it stays the same anyway, e.g. IPv6 extension headers, UDP ports. NHC framework is simple: kernel module per compression function, with callback for compression and decompression. Only UDP exists at the moment; the others are already registered so a Not Implemented warning is kprinted. Also a netlink interface for configuring NHC has to be created (e.g. for UDP you can choose a shorter CRC).