What this means
The IEEE assigned the MA-L block 0021CB to SMS TECNOLOGIA ELETRONICA LTDA. 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 00:21:CB, it is SMS TECNOLOGIA ELETRONICA LTDA hardware.
Frequently Asked Questions
Who owns MAC prefix 0021CB?
0021CB is registered to SMS TECNOLOGIA ELETRONICA LTDA 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. SMS TECNOLOGIA ELETRONICA LTDA's block covers 16,777,216 addresses.
What devices use 0021CB?
Any network device with a MAC address starting 00:21:CB was manufactured by or for SMS TECNOLOGIA ELETRONICA LTDA.