We have switches purchased in the last few years that use zmodem for firmware upload and recovery.
Annoyingly it still supports a maximum of 115200 baud, even though the serial port on the switch is physically USB-C, so on the one occasion we had a switch brick itself and had to use zmodem "in anger" it took quite a long time to upload the replacement firmware.
Annoyingly it still supports a maximum of 115200 baud, even though the serial port on the switch is physically USB-C, so on the one occasion we had a switch brick itself and had to use zmodem "in anger" it took quite a long time to upload the replacement firmware.