MDL-Error in case of OsmocomBB+OpenBTS
246tnt at gmail.com
Tue Jan 8 12:58:31 UTC 2013
The fix Andreas just pushed is what I suspected: A missing 'return'
that made the "ignore" casei, not really ignored.
What seems to happen is:
- We respond to the assignement a bit fast it seems and OpenBTS
doesn't see the first SABM at all (not in the OpenBTS trace at all)
- When OpenBTS sees the SABM, it responds with the UA frame
- OpenBTS doesn't send a new frame until quite a bit later, which
means the UA frame is resent several times by OpenBTS transceiver
application using it's filling table (which is why we see only 1 UA
frame in OpenBTS trace but multiple of them in the OsmocomBB trace)
- OsmocomBB had a bug where it was supposed to ignore the extraneous
UA frame but instead was dropping the connection because of a missing
"return" inside the switch statement.
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