in layer23 apps

we open local unix socket in layer23 app and one in osmocon another socket to communicate in between.

now in layer23 we just send (write) or receive (read) msg.

but we handle actual communication with phone is handled in osmocon. now flow of functions is main ->register_tool_server->tool_accept->un_tool_read->hdlc_send_to_phone->sercomm_sendmsg

then sercomm handles all transmission in details

then layer1 accept all data via

so i wanted to ask that how does rssi firmware is sending data directly to l1 -l2 and i would also like to ask what is actual protocol used in communication between l1 and l2