What this means
The IEEE assigned the MA-L block 409151 to Espressif Inc.. Every network interface they manufacture under this block has a MAC address beginning with these digits, followed by a unique per-device identifier. If a device on your network shows a MAC starting 40:91:51, it is Espressif Inc. hardware.
Frequently Asked Questions
Who owns MAC prefix 409151?
409151 is registered to Espressif Inc. in the IEEE MA-L registry.
What does the MA-L registry type mean?
An MA-L assignment, the IEEE's original OUI format, gives the vendor the first three octets and 16,777,216 device addresses under them. Espressif Inc.'s block covers 16,777,216 addresses.
What devices use 409151?
Any network device with a MAC address starting 40:91:51 was manufactured by or for Espressif Inc..