MAC address formatter
Reformat a MAC address between colon, dash, Cisco dot-quad and bare-hex notation, and report the multicast/locally-administered bits.
MAC address formatter takes one MAC in any common notation and prints bare hex, Cisco dot-quad, dash and colon forms, with bare hex repeated in uppercase. It also reads the first octet, reporting the multicast and locally-administered bits, which need no database. No vendor is named here; that lookup lives in MAC / OUI vendor lookup.
Questions
Which notations does it accept and produce?
It accepts colon, dash, bare hex and Cisco dot quad, in any case, by stripping the separators and requiring 12 hex digits. It prints all four notations, plus bare hex in uppercase, so you can copy whichever your switch, hypervisor or config file wants.
What are the multicast and locally administered bits?
Two flags in the first octet. The low bit set means a multicast or group address rather than one interface; clear means unicast. The next bit set means the address was assigned locally rather than out of a vendor OUI block. Both are read straight from the bits, so they are correct without any vendor database.
Why did it reject my address?
It needs exactly 12 hex digits once colons, dashes, dots and whitespace are removed. Anything else gives a message saying it is not a MAC address, naming the 12 hex digit expectation and quoting what you typed. A missing digit or a stray letter is the usual cause.
Does it tell me the vendor?
No, that is the MAC / OUI vendor lookup tool, which checks the first three bytes against a small bundled table. This one does formatting and the two RFC defined bits in the first octet, both of which are read straight from the address and need no database at all.
Does it look the address up anywhere?
No. It parses the text you typed and prints it back in other notations, with the multicast and locally administered bits reported from the first octet. There is no network request, nothing is stored, and the whole thing runs in this tab, so it works with the network switched off.