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Bug #5926

closed

codec_pref.c prohibits running a BTS only on TCH/F with only 12k2 AMR

Added by neels 12 months ago. Updated 3 months ago.

Status:
Resolved
Priority:
Normal
Assignee:
Category:
-
Target version:
-
Start date:
02/28/2023
Due date:
% Done:

100%

Spec Reference:

Description

In osmo-bsc.cfg, I have only TCH/F timeslots configured.
I want to force 12k2 AMR, hence I have

amr tch-f modes 7

and I figure this makes sense too:

msc 0
 codec-list fr3
 amr-config 12_2k allowed
 amr-config 10_2k forbidden
 amr-config 7_95k forbidden
 amr-config 7_40k forbidden
 amr-config 6_70k forbidden
 amr-config 5_90k forbidden
 amr-config 5_15k forbidden
 amr-config 4_75k forbidden

Now codec_pref.c tells me on BSC startup:

20230228033728416 DMSC FATAL network amr tch-h mode config of BTS 0 does not intersect with amr-config of MSC 0 (codec_pref.c:496)
20230228033728416 DMSC FATAL network amr tch-h mode config of BTS 1 does not intersect with amr-config of MSC 0 (codec_pref.c:496)
20230228033728416 DMSC ERROR Configuration contains mutually exclusive codec settings -- check configuration! (osmo_bsc_main.c:988)
20230228033728416 DMSC ERROR You should really fix that! However, you can prevent OsmoBSC from stopping here by setting 'allow-unusable-timeslots' in the 'network' section of the config. (osmo_bsc_main.c:991)

Pointless when there are no physical channel configurations that could possibly run TCH/H at all.
I could add 'allow-unusable-timeslots', but a) there aren't any and b) i would switch off sanity checking for my TCH/F timeslots.

Related, I cannot configure 'tch-h modes' to be empty.

So I have to allow at least one tch/h capable AMR rate

network
 bts 0
  amr tch-f modes 7 
  amr tch-h modes 0

msc 0        
 codec-list fr3
 amr-config 12_2k allowed
 amr-config 10_2k forbidden
 amr-config 7_95k forbidden
 amr-config 7_40k forbidden
 amr-config 6_70k forbidden
 amr-config 5_90k forbidden 
 amr-config 5_15k forbidden
 amr-config 4_75k allowed

So for tch-f I am allowing only 7 (12k2) as I want to achieve for testing,
but I still have to configure some tch-h and allow one of its rates for osmo-bsc to start without complaining.

In codec_pref.c, we should probably ignore TCH/H when there is no TCH/H capable timeslot present in a BTS.
Also we should ignore TCH/F when no TCH/F capable timeslot is present.
In extension, if a BTS has no TCH timeslots at all, we should not check codecs at all.


Files

osmo-bts-0.cfg osmo-bts-0.cfg 1.59 KB cfg without TCH/H timeslots, where osmo-bsc complains about TCH/H codecs being impossible neels, 02/28/2023 02:47 AM
Actions #1

Updated by laforge 4 months ago

  • Assignee set to jolly
Actions #2

Updated by jolly 3 months ago

  • Status changed from New to In Progress
  • % Done changed from 0 to 80

This is an easy one. I will provide a patch to Gerrit, to skip the AMR on half rate, if there is no half rate time slot and no dynamic time slot assigned.

Actions #3

Updated by jolly 3 months ago

To make it complete, we want to skip any check for full rate AMR support, if no full rate time slot is configured.

Actions #4

Updated by jolly 3 months ago

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

Patch has been merged. Neels and me verified that it works in our test setups.

Actions

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