EM7455 multiple mac addresses

IoT Modules
1

Hello All,

Edit: I posted this same message in Debian forums. Am hoping someone can explain why each module shows three different mac addresses,just out of curiosity.
Is it /dev/ttyUSB0 , /dev/ttyUSB1, /dev/ttyUSB2 has one,each? Don’t seem right.

Debian Bullseye

Setting up a dual / failover wwan setup that is using two identical Sierra Wireless modems.
To circumvent the wwan# from changing from one to the other when making a NetworkManager connection,I placed entries for each at /etc/systemd/network/10-interface#.link
[Match]
MACAddress=
[Link]
Name=wwan0

When i do this,reboot, each of the two wwan modules comes up in 'ip a; with a totally different mac address showing.
Each one will show three different mac addresses if i keep making another entry in /etc/systemd/network
I am missing something I’m sure.

Thanks

2

The mac address is a random one generated by the OS/driver. It will change with every boot as you’ve noticed. The module transports raw IP packets without any L2 header, so it has no knowledge of any mac addresses at all.

You should ignore the mac address. Match on some persistent module attribute (serial number, IMEI, bus connection, attached SIM, other?) if you need to create a fixed mapping of some sort.

3

Thank You dl6162

I never knew of this,mac address changing, until trying to do the mapping thing for the module.
I learned something from this.
OK will use the IMEI as the identifier.

Thanks again