Project

General

Profile

Actions

Bug #6457

open

PLMN: 3-digit MNC problem in umts_cell_id

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

Status:
In Progress
Priority:
Normal
Assignee:
Target version:
-
Start date:
05/19/2024
Due date:
% Done:

80%

Spec Reference:

Description

a PLMN of 01-001 is different from 01-01, which is why we have the bool mnc_3_digits in osmo_plmn_id.
struct umts_cell_id in osmo-hnbgw.git however doesn't use osmo_plmn_id, and has no flag like mnc_3_digits.

Instead there seems to be a single, global indicator at g_hnbgw->config.plmn.mnc_3_digits.

Looking at hnbgw_rx_hnb_register_req(), we have the mnc_3_digits flag parsed from HNBAP, and just discard it:

        struct osmo_plmn_id plmn;
        ...
        osmo_plmn_from_bcd(ies.plmNidentity.buf, &plmn);
        ctx->id.mcc = plmn.mcc;
        ctx->id.mnc = plmn.mnc;
        cell_id_str = umts_cell_id_name(&ctx->id);

In consequence, umts_cell_id_name() and umts_cell_id_from_str() cannot properly convey the 2-digit / 3-digit difference.

The global flag is a dirty hack at best. It's unlikely to bother anyone in reality, but it breaks operating mixed 3-digit-mnc and 2-digit-mnc PLMNs, no matter how it is configured.

It would be trivial to just transport the proper 3-digit flag along everywhere, like we already do in our other CNI implementations.

Actions #1

Updated by neels about 2 months ago

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

Also available in: Atom PDF

Add picture from clipboard (Maximum size: 48.8 MB)