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Computer Network 2021
random-access memory (RAM) when the NIC initializes. Figure 3-15 illustrates the MAC address
format.
Figure 3-14 shown an Ethernet Technologies and the OSI Model
Figure 3-15 shown a MAC Address Format
Without MAC addresses, the LAN would be a group of computers without identifiers, and
it would be impossible to deliver an Ethernet frame. Therefore, at the data link layer, a header
and a trailer are 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. Ethernet and 802.3 LANs are broadcast
networks. All stations see all frames. Each station must examine every frame to determine
whether that station is the desired destination. On an Ethernet network, when one device wants
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