Thanks for your detailed and generous explanation. I am a beginner on openBSC, looking forward to your guidance.

There are some files in the attachment, i don't know whether they are enough.

1. The config files of osmo-trx, osmo-bts-trx and osmo-nitb. They are the original files downloaded from git repository, and i select one of them to run the application, i don't know whether they are correct, and i don't know how to modify it.

2. config.log files of osmo-trx, osmo-bts-trx and osmo-nitb. I don't know whether they are the logs you mentioned in your reply.  I guess not, but i don't know how to get the complete logs, Maybe you give me some tips ?

3. pcap file which includes the data package whose src ip and dst ip are the 127.0.0.1, these packages were captured using wireshark.

I guess there are some problems on the config file osmo-nitb-ipa.cfg , i select it as the config file without reason, because i don't know how to config the file.

thanks for your help again.

Hi,

the problem is not in osmo-bts-trx <-> osmo-trx, that's working fine so
far on your setup (sending a POWEROFF at startup is fine since then it
makes sure the osmo-trx is powered off before configuring it and finally
running POWERON on it). It won't be configured until the BSC (in your
case osmo-nitb) instructs osmo-bts-trx on how to do it through Abis OML
connection.

The problem is here:

On 5/9/20 3:15 AM, cruise wrote:

*_/About one minutes later, the osmo-bts-trx will exit automatically,
and the following messages was printed./_*

<0012> e1_input.c:243 abis_sendmsg: msg->dst == NULL: 0c 12 01 90 0f 00 c8
<0012> e1_input.c:243 abis_sendmsg: msg->dst == NULL: 0c 12 01 88 12 06
00 00 00 00 00 00
<000d> abis.c:143 Signalling link down
<0001> bts.c:293 Shutting down BTS 0, Reason Abis close
Shutdown timer expired

The  Abis connection, be it OML or RSL, between the BTS and the BSC (in
your case osmo-nitb) fails at some point. Unfortunately unless you
provide config files, complete logs and pcap files it's difficult to
tell you more. Please next time provide those while reporting.

*3. osmo-nitb*

FYI, osmo-ntib is deprecated and not maintained since years ago.
Please better use new software stack:
https://osmocom.org/projects/cellular-infrastructure/wiki