Ethernet MAC Frames

As shown in Figure 4.3, an Ethernet MAC frame starts with a header that includes its destination and source MAC addresses. It ends in a frame check sequence (FCS) field that contains a CRC code that is used to detect transmission errors.

Figure 4.3. General format of an Ethernet frame.

Preamble and Start Frame Delimiter Patterns

A station transmits two special bit patterns—a preamble and a start frame delimiter—prior to sending a MAC frame. Figure 4.4 shows a MAC frame preceded by its preamble and start frame delimiter.

Figure 4.4. Preamble, start frame delimiter, and MAC frame.

The preamble pattern tells ...

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