What does the trailer of an Ethernet frame consist of?

The trailer of an Ethernet frame consists of the Frame Check Sequence (FCS). The FCS is a vital component of the Ethernet frame, as it provides error detection capabilities. Upon transmission, the sender calculates the FCS using a cyclic redundancy check (CRC) algorithm based on the content of the frame. This calculated checksum is then appended to the end of the frame as the trailer.

When the receiving device gets the frame, it performs the same CRC calculation. If the result matches the FCS in the trailer, it indicates that the frame was transmitted without errors. If there is a discrepancy, the receiving device knows that the frame was corrupted during transmission and can request a retransmission if needed.

The other components listed, such as the Start Frame Delimiter (SFD), Preamble, and Destination Address, are all part of the frame, but they are located in different sections. The Start Frame Delimiter and Preamble are found at the beginning of the Ethernet frame, serving to signal the start of the data link layer frame and prepare the receiving device for the incoming frame. Meanwhile, the Destination Address is part of the frame header, which contains information about the intended recipient of the frame.