The address field (AF) is the control field of a transmission frame( block, data packet, datagram, etc.) for holding station, connection and network addresses. It contains the identification of the data station in which the sequence control is executed during data transmission.
All transport-oriented protocols have one or more address fields, for the source address and/or the destination address. In the case of LAN data packets, the address field contains two address fields: that of the destination address and that of the source address. Each address field consists of 8 bytes. The first bit of the Destination Address field is used to define the address as a single or group address. The second bit of the Send Address is used to distinguish between locally and globally managed addresses.