Hi Harald,
Much appreciate the prompt response.
Just try to save a piece of telco history, the Nokia *Site family made the mobile technology widely available in my country. At some point 2 out of the 3 operators complete network was based on Site (and other Nokia PDH/SDH MW) products.
think it would be best to have a pcap file of the LAPD traffic.
Will try to create one tomorrow.
The OML part works correctly, the BTS even tells OMUSIG is up and running, only TRXSIG (RSL) waits for LAPD and nothing happens. And yes: the RSL config is correct on both the BTS and in Osmo-BSC :-)
Now that we talk about it, some faint memory ring a bell about what might go wrong:
The UltraSite bootstrap differs from InSite and MetroSite in a sense that 1. after the NOKIA_BTS_RESET command it takes a lot of time for it come up (we have the "nokia_site bts-reset-timer" to handle that), and 2. even after that the TRX SW is not loaded yet: once the BSC issues "NOKIA_BTS_START_DOWNLOAD_REQ" the SW load starts but that takes another good amount of time, but Osmo-BSC starts the RSL bootstrap right away and times out (obviously, as the RSL link is not yet available as the TRX SW is not loaded yet).
I am pretty sure the above is the issue. I implemented (was more like a nasty hack) a similar timeout for the RSL as the "nokia_site bts-reset-timer" for the OML (it was so big of a hack, I never shared it I believe).
The correct way to handle this would be not via (another) timeout, but a way to poll the BTS if the TRX SW is loaded yet, but I suspect we have no idea nor documentation available to figure out how to do that. So it might be a timeout after all...
Non the less, I think this can be fixed with a bit of help :-)
Regards, Csaba