CC2538DK as SLIP/BR is missing packets

Hey guys,

I am using CC2538DKs and OpenMotes with RIOT for my DTLS examples. However I'm facing the following problem: I am using the gnrc_border_router image on one CC2538DK that is acting as SLIP and connected to a virtual machine via USB/UART. That works fine in general. However one of my testing examples involves a client on another board that is first waiting until it gets an IP address assigned and then starts a DTLS connection to the server (that is behind the border router on the same system). I am seeing two different different behaviours with different boards that is giving me a hard time:

1. CC2538DK: I need to reset the SLIP and then the client CC2538DK board a couple of times. Every 3rd to 5th time the connection (CLIENT_HELLO) works fine. However I am tracing "in the air" and at the tap0 interface with wireshark: The CLIENT_HELLO is successfull on the air nearly every time - but not on the tap0 interface. I am using the fd00::/64 and sending to "fd00:dead:beef::1". So it looks like the SLIP radio is not receiving every packet although it's correctly addressed and on the air.

2. OpenMote: Same procedure: I need to reset the SLIP first and then the mote a couple of time. I am seeing the CLIENT_HELLO in the air and here also most of the time on the SLIP/tap 0 interface. My DTLS Server is also receiving the CLIENT_HELLO and answers with the CLIENT_VERIFY packet which is then resent around ~25 times. I can see those packets on the tap0 interface - but I never see them in the air. So in this case it looks like the SLIP radio is not sending every packet.

Has anyone any idea why this could happen to me? I've already tried using fixed global adresses but that doesn't improve much. To run my tests I'm now constantly resetting everything which is a very time consuming and frustrating task. Any idea is appreciated. (Screenshot available here:


Bye, Michael