00:1A:2B:3C:4D:5E (This format is commonly used on most of the network, Linux and Unix like devices) 00-1A-2B-3C-4D-5E (This format is commonly used on Windows based systems) 001.A2B.3C4.D5E (This format is commonly used on Cisco routers and switches)
What is OUI? OUI (Organizationally Unique Identifier) is a 24-bit number that uniquely identifies a vendor or manufacturer. They are purchased and assigned by the IEEE. The OUI is basically the first three octets of a MAC address. For example, these are examples of OUI:00:50:73 -- this is owned by Cisco Systems. Inc 00-50-BA -- this is owned by D-Link Corporation