What does 'SFD' stand for in an Ethernet header?

The term 'SFD' in an Ethernet header stands for 'Start Frame Delimiter'. In an Ethernet frame, the SFD is a specific sequence of bits that indicates the start of the frame's data payload. It helps the receiving device recognize where the data begins after the preamble, which is a series of bits used for synchronization.

Specifically, the SFD is defined as the first byte immediately following the preamble and is represented as the hexadecimal value 0xAB. This is crucial for proper framing and ensuring that the data can be accurately interpreted by the receiving hardware. The SFD indicates that the actual data field of the frame is about to begin, which is essential for maintaining the integrity of the information being transmitted over the network.

Understanding the role of the SFD is important in Ethernet framing and overall data communication, helping to troubleshoot issues related to data transmission and ensuring that devices communicate efficiently and correctly. This clarity in frame structure is part of what allows networking equipment to process incoming data accurately.