Check reflection filter

[Noki]

On a core router setup with an additional AP mesh interface we see reflections that should be mostly filtered out by our reflection filter but we still see the following errors in the log:

Fri Mar  6 08:31:22 2026 daemon.err bird: bgpdisco_2_switch0_22: Error: Bad BGP identifier: 0a1fd401
Fri Mar  6 08:31:22 2026 daemon.debug bird: bgpdisco_2_switch0_22: State changed to stop
Fri Mar  6 08:31:22 2026 daemon.debug bird: bgpdisco_2_switch0_22: State changed to flush
Fri Mar  6 08:31:22 2026 daemon.debug bird: bgpdisco_2_switch0_22: State changed to down
Fri Mar  6 08:31:22 2026 daemon.debug bird: bgpdisco_2_switch0_22: Starting
Fri Mar  6 08:31:22 2026 daemon.debug bird: bgpdisco_2_switch0_22: State changed to start
Fri Mar  6 08:31:22 2026 daemon.err bird: bgpdisco_4_wlan5_mesh: Error: Bad BGP identifier: 0a1fd401
Fri Mar  6 08:31:22 2026 daemon.debug bird: bgpdisco_4_wlan5_mesh: State changed to stop
Fri Mar  6 08:31:22 2026 daemon.debug bird: bgpdisco_4_wlan5_mesh: State changed to flush
Fri Mar  6 08:31:22 2026 daemon.debug bird: bgpdisco_4_wlan5_mesh: State changed to down
Fri Mar  6 08:31:22 2026 daemon.debug bird: bgpdisco_4_wlan5_mesh: Starting
Fri Mar  6 08:31:22 2026 daemon.debug bird: bgpdisco_4_wlan5_mesh: State changed to start

0a1fd401 translates to 10.31.212.1 and is the Router ID (birdc show status). The check for the error looks as follows:

  956   /* RFC 6286 2.2 - router ID is nonzero and AS-wide unique */
  957   if (!id || (p->is_internal && id == p->local_id))
  958   { bgp_error(conn, 2, 3, pkt+24, -4); return; }

We should look into the following:

• Is this really log noise we should tolerate or is there an issue we should address?
• Is this something we can now filter since we introduced deterministic random MAC addresses for mesh interfaces with 0833565
• Rewrite the reflection filter comment to match the current state with deterministic random MAC addresses

[Noki]

Idea: With the deterministic MAC addresses generated by bbb-configs that are based on host and interface name, we should now be able to filter based on these, without the need to learn addresses at all.