Project

General

Profile

Actions

Bug #6152

open

built-in MNCC: forward the @Low layer compatibility I@ IE to the called subscriber

Added by fixeria 6 months ago. Updated 2 months ago.

Status:
In Progress
Priority:
Normal
Assignee:
Category:
Call Control
Target version:
-
Start date:
08/28/2023
Due date:
% Done:

50%

Resolution:
Spec Reference:
Tags:
CSD

Description

The Low layer compatibility I IE is usually present in mobile-originated (CC) Setup messages related to date calls (CSD). According to 3GPP TS 24.008, section 9.3.23.1.7, this IE shall be included in the mobile-terminated (CC) Setup message if the calling user specified it. Currently this IE is simply ignored by the built-in osmo-msc's MNCC and not forwarded to the called party.


Files

osmo_csd_rsl_sign.pcapng.gz osmo_csd_rsl_sign.pcapng.gz 7.44 KB fixeria, 12/20/2023 12:52 PM

Related issues

Related to OsmoMSC - Feature #4394: Circuit Switched Data (CSD) Support in osmo-mscResolvedosmith02/13/2020

Actions
Actions #1

Updated by fixeria 6 months ago

  • Related to Feature #4394: Circuit Switched Data (CSD) Support in osmo-msc added
Actions #2

Updated by laforge 4 months ago

  • Assignee set to jolly
Actions #3

Updated by jolly 3 months ago

  • Status changed from New to In Progress
Actions #4

Updated by jolly 2 months ago

  • % Done changed from 0 to 50

Patches prepared, but not yet pushed to Gerrit.
I have no phone to test it.

Actions #5

Updated by laforge 2 months ago

jolly wrote in #note-4:

Patches prepared, but not yet pushed to Gerrit.
I have no phone to test it.

This is sad, adn we should make sure you have some devices that speaks CSD. Will look into that, but that will take some time.

Unrelated to the above, we generally want to have automatic test coverage, so a TTCN3 MSC test for MO and MT csd should verify the LLC is passed through transparently on MO and MT.

Actions #6

Updated by fixeria 2 months ago

laforge wrote in #note-5:

This is sad, adn we should make sure you have some devices that speaks CSD. Will look into that, but that will take some time.

AFAIU, the problem here is that jolly has no phone that would include the Low layer compatibility I IE in MO SETUP.
I do have a few (Calypso based SE K200/K220 definitely does include it), so I could do some testing if I had patches.

Unrelated to the above, we generally want to have automatic test coverage, so a TTCN3 MSC test for MO and MT csd should verify the LLC is passed through transparently on MO and MT.

We do have TTCN-3 test cases verifying MO and MT data calls in ttcn3-msc-test:

  • TC_lu_and_mo_csd,
  • TC_lu_and_mt_csd.

We can extend those to verify forwarding of the LLC/HLC IEs, but I would go for adding separate testcases for this ticket (re-using the existing code).

Also, some time ago I worked on adding TTCN-3 testcases for osmo-msc, testing MS-to-MS voice and data call with the built-in MNCC.
Currently we only test either the MO or the MT signalling with external MNCC, but not with built-in MNCC.
I will find that WIP code and push it to a branch.

Actions #7

Updated by laforge 2 months ago

On Tue, Dec 19, 2023 at 04:31:26PM +0000, fixeria wrote:

Currently we only test either the MO or the MT signalling with external MNCC, but not with built-in MNCC.
I will find that WIP code and push it to a branch.

yes, that would make sense to have tests covering built-in mncc.

Actions #8

Updated by fixeria 2 months ago

fixeria wrote in #note-6:

I do have a few (Calypso based SE K200/K220 definitely does include it), so I could do some testing if I had patches.

Please find a PCAP attached. The The Low layer compatibility 1 is sent by the calling phone (in frame 125) and being forwarded to the called phone (in frame 197), as expected.

Actions

Also available in: Atom PDF

Add picture from clipboard (Maximum size: 48.8 MB)