|  | 6.3 | MAC Addressing
| 6.3.1 | Data link layer MAC identifiers
Without MAC addresses, we would have a group of nameless computers on your LAN. Therefore, at the data link layer, a header, and possibly a trailer, is added to upper layer data. The header and trailer contain control information intended for the data link layer entity in the destination system. Data from upper layer entities is encapsulated in the data link layer header and trailer. To learn more about how these OUIs are assigned, and to search for current address assignments, go to:
| Web Links
| OUIs Frequently Asked Questions