I'm having some trouble with a rather simple sensor network application: my goal is to query a sensor node (RIOT) using COAP/UDP over 6lowpan from a RasPi. The Pi is equipped the well known openlabs 802.15.4 transceiver module, it runs latest Raspbian Jessie with a self compiled wpan-enabled Linux-Kernel. The sensor node is an Atmel samr21-xpro for my initial tests I installed the gnrc_networking example from latest RIOT master. I setup a lowpan device on the Pi with same channel and pan-id as the RIOT node.
My initial findings: - ping and data transmission using link local address works fine - ping and data transmission using ULAs doesn't work in any direction - setup ULA as follows: - RasPi `sudo ip addr add fd59:7f5:2065:7622::2/64 dev lowpan0` - RIOT-node `ifconfig 7 add fd59:7f5:2065:7622:0000:0000:0000:0003`
I enabled some debugging under `sys/net/gnrc/network_layer` in `icmpv6`, `ipv6`, and `ndp` to dig a little deeper. Further I used wireshark+dumpcap on the RasPi to sniff lowpan traffic. My observations for pings RasPi <-> RIOT using ULAs:
1. RIOT -> RasPi:
- no packets get out, so no wireless transmission visible on sniffer - packet send fails with "ipv6: error determining next hop's link layer address" in gnrc_ipv6.c:_send 
2. RasPi -> RIOT:
- sniffer sees neighbor solicitation from RasPi for ULA of RIOT node (fd59:7f5:2065:7622::3) - RIOT debug messages show: - NS is received by RIOT - RIOT sets neighbor cache entry for RasPi ULA - RIOT assembles neighbor advertisement (NA) - send of NA fails as before in  - RasPi cannot resolve ULA, thus ping fail
Has anybody (recently) tried a similar setup using RasPi with lowpan module to connect to a RIOT node? In the RIOT wiki I found an old entry for a RasPi border gateway, this looks quite similar though I don't need the forwarding part (yet). Or asking differently: should ping via ULA work as I would expect or is there any reason that this should not work with 6lowpan. The same setup between e.g. Linux and OS X using ULAs works fine: I know 6lowpan is not IPv6 and vis-versa ...
Thanks in advance for any hint on solving this,
: http://openlabs.co/store/Raspberry-Pi-802.15.4-radio : https://github.com/RIOT-OS/RIOT/blob/master/sys/net/gnrc/network_layer/ipv6/gnrc_ipv6.c#L627