8 Jan
2013
8 Jan
'13
3:51 p.m.
Anything OpenBTS is doing wrong?
On Tuesday, January 8, 2013, Pavel Baturko wrote:
Thanks for explanations and fast fix! It seems that
now all works as
should be.
Pavel
On Tue, Jan 8, 2013 at 12:58 PM, Sylvain Munaut <246tnt@gmail.com<javascript:_e({},
'cvml', '246tnt(a)gmail.com');>
wrote:
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.
Cheers,
Sylvain