It is the combination of the OUI and the vendor-assigned number that ensures that no two network adapters have the same MAC address. The vendor-assigned portion of the MAC address is just that, the alphanumeric identifier assigned by the vendor. The OUI is administered by the IEEE and identifies the vendor of the network adapter.

The OUI is 00-08-a1, and the vendor-assigned number is 08-c8-13. This MAC address is used for the Fast Ethernet adapter on the computer in question. The MAC address on a computer might look like this: 00-08-a1-08-c8-13. It is 48 bits (6 bytes) long and is made up of two parts: the organizational unique identifier (OUI) and the vendor-assigned address, as illustrated in Figure 5-1. Ethernet Numbers: Ethernet numbers include the 48-bit media access. MAC Addresses Each Ethernet interface is assigned a unique MAC address at the time of manufacture. For this discussion of LAN environments, the physical address (also known as the Media Access Control address) is relevant.Ī MAC address is the physical address of the device. The first 24 bits of the MAC address consist of an Organizationally Unique Identifier (OUI) assigned to a vendor by the IEEE, which is why they are also called vendor codes.

Two types of addresses are found in a network: the logical (OSI model Layer 3, network) and the physical (OSI model Layer 2, data link). To be a part of any network, you must have an address so that others can reach you. The MAC address is the unique serial number burned into each network adapter that differentiates the network card from all others, just as your house number is unique on your street and identifies your home from all others.

Mac address vendor codes.