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Bug #6324

open

Making a data call results in B0RKEN lchans

Added by keith about 2 months ago. Updated about 2 months ago.

Status:
New
Priority:
Normal
Assignee:
Category:
-
Target version:
-
Start date:
01/05/2024
Due date:
% Done:

0%

Spec Reference:

Description

I made a data call from a GSM modem and ended up with a CHAN NACK from osmo-bts (as is to be expected, I suppose)

Should we enhance osmo-bsc's NACK handling to do something a little more helpful than just B0RK the channel?


Files

data_call_nack_b0rken.pcapng data_call_nack_b0rken.pcapng 3.09 KB keith, 01/05/2024 08:30 PM
Actions #1

Updated by laforge about 2 months ago

the strange part is why you can make that call in the first place.

IMHO:
  • osmo-bts-sysmo should not advertise CSD capabilities to osmo-bsc (only osmo-bts-trx does)
  • osmo-bsc should hence reject any assignment for CSD it receives from the MSC, and it should never even get to he point where it tries to activate unsupported channel modes on Abis.

This is exactly what would happen in case of unsupported audio codecs, so I'm surprised it behaves differently for CSD. Looking at the code, it seems it was forgotten to even add a BTS_FEAT_ flag? Maybe there is some other mechanism that I don't spot immediately?

Actions #2

Updated by laforge about 2 months ago

  • Assignee set to osmith
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