Bug #4364
open
osmo-bts-trx configured with 2 TRX and osmo-trx with 1 TRX -> bad behavior
Added by pespin over 4 years ago.
Updated almost 4 years ago.
Description
Configure osmo-bsc + osmo-bts-trx to run with 2 TRX, and osmo-trx to run with only one TRX (chan 0).
Current behavior: the network runs fine (of course only using TRX0) and osmo-bts is lots of times per second printing the error message:
20200114161445605 DTRX <000b> trx_if.c:1110 phy0.1: send() failed on TRXD with rc=-1 (Connection refused)
So there seems to be several flaws here:
- If that log line is printed, it means the TRX1 is seen as ON (
trx_if_powered(l1h) is returning true), but it's not since osmo-trx doesn't use it, so it shouldn't be on
- Upon that failure, osmo-bts-trx should either: A) continue running but tell BSC over OML that the TRX is down, or B) stop the process (exit).
The second point on the task description has already been fixed since a while ago (bts exits now). I still need to look at what's the current status for the first point.
If that log line is printed, it means the TRX1 is seen as ON (trx_if_powered(l1h) is returning true), but it's not since osmo-trx doesn't use it, so it shouldn't be on
Ah, there is an interesting detail. In a multi-trx setup POWERON/POWEROFF commands are sent only to the first transceiver (TRX0), not to all TRX1..N. That's why osmo-bts-trx thinks that your second transceiver is powered on. There's basically no way to know on the BTS side how many transceivers are actually enabled in osmo-trx. But still... osmo-bts-trx sends RXTUNE/TXTUNE and SETSLOT commands to each transceiver individually, and obviously it would not get any response for TRX1..N in your case.
Upon that failure, osmo-bts-trx should either: A) continue running but tell BSC over OML that the TRX is down
I think A) is the correct approach. This is what the A-bis specifications require us to do.
I started by sanitizing the code by using an FSM. From there, we can start adding states or query state of other TRXs:
https://gerrit.osmocom.org/c/osmo-bts/+/19167 bts-trx: introduce TRX provisioning FSM
We can now more easily for instance have a "trx_if_powered()" well implemented really per trx and not per phy_link.
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