CITS3002 Computer Networks  
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Ethernet Addressing Schemes

Each 802.3 packet contains the source and destination address, each of 6 bytes (48 bits).

bbb

  • If all 48 destination bits are set to 1, the packet is a broadcast address destined for all stations on a LAN.

  • The high-order bit (bit 47) is used to indicate addressing domains, 0 being for individual addresses and 1 being for multicast addresses (to deliver packets to a group of stations).

  • Bit 46 (high-order less one) indicates whether the address is for the current LAN or for a more global station on another LAN.

  • Using 246 bits (7 * 1013 stations) each device in the world can have a unique Ethernet card number (assigned by the IEEE).

Of course it is up to the Network Layer to determine how to get to other stations not on your LAN.

CITS3002 Computer Networks, Lecture 4, Local Area Networks (LANs and WLANs), p13, 20th March 2024.