I just recently learn about openbsc, and still in the phase of

compiling and try to run the osmo-nitb app.

1st problem 

The problem is one of my teammate said the osmo-nitb will also started/call

the osmo-sgsn program, but after examine the code, I still don't know how the 

osmo-sgsn is called from osmp-nitb, may be I was wrong, anyone can help me with this, how can I activate osmo-sgsn from osmo-nitb, with extra arguments?

2nd problem

Another question, when I try to compile osmo-sgsn, the gtp lib is missing, as define in the makefile:

I don't know where to get this lib, so I modified by adding osmo-sgsn to the else clause as-well to have osmo-sgsn compiled. I still can run osmo-sgsn, but it show error about the gtp socket, i think the configuration is not correct, but not because of missing gtp lib, should this be a problem?

Best regards,

Dai