I pushed a new commit to the feature-coap-wip branch: https://github.com/Ell-i/Runtime/commit/c4129e26e163c25f4c73c48d58622c1505091318 It has now a standalone test case also for UDP. The UDP sockets seem to work, but something goes wrong when calling the upper layer protocol; the packet doesn't seem to get up right. I'll continue tomorrow, trying to get UDP working and adding a test case for IP. --Pekka