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Bug #4614

"bogus channel load sample" when using BS-11, Nokia or Ericsson BTS

Added by laforge 27 days ago. Updated 8 days ago.

Status:
In Progress
Priority:
Normal
Assignee:
Category:
Ericsson BTS
Target version:
-
Start date:
06/15/2020
Due date:
% Done:

30%

Spec Reference:

Description

Mon Jun 15 15:36:12 2020 DRLL chan_alloc.c:208 (bts=0) bogus channel load sample (used=0 / total=0)
Mon Jun 15 15:36:13 2020 DRLL chan_alloc.c:208 (bts=0) bogus channel load sample (used=0 / total=0)

Also, interestingly:

OsmoBSC> show trx
TRX 0 of BTS 0 is on ARFCN 121
Description: (null)
  RF Nominal Power: 24 dBm, reduced by 0 dB, resulting BS power: 24 dBm
  NM State: Oper 'NULL', Admin 'Unlocked', Avail 'Power off'
  RSL State: connected
  Baseband Transceiver NM State: Oper 'NULL', Admin 'unknown 0x0', Avail 'Power off'
  E1 Signalling Link:
    E1 Line 2, Type dahdi: Timeslot 1, Mode RSL
    E1 TEI 1, SAPI 0

I think the problem is that the Siemens BS-11 MO structure is quite unlike what TS 12.21 describes, so the baseband transceiver object is simply never initialized.

The " OC=SIEMENSHW INST=(03,00,00)" might be can idea?

History

#1 Updated by laforge 8 days ago

  • Subject changed from "bogus channel load sample" when using BS-11 BTS to "bogus channel load sample" when using BS-11 BTS or Ericsson BTS
  • Category set to Ericsson BTS

Also appears on RB2308:

<0000> chan_alloc.c:208 (bts=0) bogus channel load sample (used=0 / total=0)

#2 Updated by tnt 8 days ago

On the RBS those should clear up when it's actually running.

#3 Updated by laforge 8 days ago

  • Subject changed from "bogus channel load sample" when using BS-11 BTS or Ericsson BTS to "bogus channel load sample" when using BS-11, Nokia or Ericsson BTS

also appears when using an InSite.

#4 Updated by laforge 8 days ago

  • Status changed from New to In Progress
  • % Done changed from 0 to 30

I think there is a wrong assumption in the code that prints the message. A total count of logical channels of '0' is perfectly valid for any BTS until it is operational.

The code tries to implement this in trx_is_usable() which is not implemented for most BTS models:

bool trx_is_usable(const struct gsm_bts_trx *trx)
{
        /* FIXME: How does this behave for BS-11 ? */
        if (is_ipaccess_bts(trx->bts)) {
                if (!nm_is_running(&trx->mo.nm_state) ||
                    !nm_is_running(&trx->bb_transc.mo.nm_state))
                        return false;
        } else if (is_ericsson_bts(trx->bts)) {
                /* The OM2000 -> 12.21 mapping we do doesn't have separate bb_transc MO */
                if (!nm_is_running(&trx->mo.nm_state))
                        return false;
        }

        return true;
}

Since this is highly BTS model specific, the function should actually likely become part of bts_model_*, where it needs to be implemented for all BTS models. That requires testing on all of those.

An interim patch simply disables the message for the 'total == 0' situation: https://gerrit.osmocom.org/c/osmo-bsc/+/19132

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