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Bug #2294

T200 values set by OML (TS 12.21) are ignored

Added by laforge about 2 years ago. Updated 11 days ago.

Status:
Resolved
Priority:
High
Assignee:
Category:
-
Target version:
-
Start date:
05/27/2017
Due date:
% Done:

100%

Spec Reference:

Description

When we receive configuration for the T200 timeouts of the LAPDm layer from the BSC, we ignore them, see the following code snippet:

»·······/* 9.4.53 T200 */
»·······if (TLVP_PRESENT(&tp, NM_ATT_T200)) {
»·······»·······payload = TLVP_VAL(&tp, NM_ATT_T200);
»·······»·······for (i = 0; i < ARRAY_SIZE(btsb->t200_ms); i++) {
»·······»·······»·······uint32_t t200_ms = payload[i] * abis_nm_t200_ms[i];
#if 0
»·······»·······»·······btsb->t200_ms[i] = t200_ms;
»·······»·······»·······DEBUGP(DOML, "T200[%u]: OML=%u, mult=%u => %u ms\n",
»·······»·······»·······»·······i, payload[i], abis_nm_t200_mult[i],
»·······»·······»·······»·······btsb->t200_ms[i]);
#else
»·······»·······»·······/* we'd rather use the 1s/2s (long) defaults by
»·······»·······»······· * libosmocore, as we appear to have some bug(s)
»·······»·······»······· * related to handling T200 expiration in
»·······»·······»······· * libosmogsm lapd(m) code? */
»·······»·······»·······LOGP(DOML, LOGL_NOTICE, "Ignoring T200[%u] (%u ms) " 
»·······»·······»·······»·······"as sent by BSC due to suspected LAPDm bug!\n",
»·······»·······»·······»·······i, t200_ms);
#endif
»·······»·······}
»·······}

AFAIR this relates to the T200 values bein in milli-seconds, and shorter than our overall delay between the LAPDm implementation and the actual air interface (L1-L2 queue, radio modem, ...). So the counters would have to be clocked by the GSM time, not by system time?


Related issues

Related to OsmoBTS - Feature #3906: Automatically adjust LAPDm timer values with 'fn-advance' parameterResolved04/06/2019

Related to OsmoBTS - Bug #4037: LAPDm N200 values are incorrectResolved06/02/2019

History

#1 Updated by laforge 22 days ago

  • Assignee set to laforge
  • Priority changed from Normal to High

#2 Updated by laforge 22 days ago

  • Related to Feature #3906: Automatically adjust LAPDm timer values with 'fn-advance' parameter added

#3 Updated by laforge 22 days ago

  • Status changed from New to In Progress

#4 Updated by laforge 22 days ago

  • Related to Bug #4037: LAPDm N200 values are incorrect added

#5 Updated by laforge 20 days ago

  • % Done changed from 0 to 80

See https://gerrit.osmocom.org/c/osmo-bts/+/14337 for a proposd implementation

#6 Updated by laforge 11 days ago

  • Status changed from In Progress to Resolved
  • % Done changed from 80 to 100

patch merged

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