The purpose of the FCS field is to transmit the extra checksum characters added to a frame in "xyz" protocol for error detection. The most popular algorithm I've used is the CRC (cyclic redundancy check) employed in things like ethernet or PPP on a routed network.
Keep in mind that ethernet defines that the errored frame should be discarded, but ethernet takes no action to cause the frame to be retransmitted. Typically most tech's see it as unnecessary overhead and opt to rely on CSMA\CD or CSMA\CA if the route is not deemed to carry time sensitive data.
Hope that clears things up a bit.
Each Ethernet frame contains a trailer with a cyclic redundancy check (CRC) of the frame contents. After reception of a frame, the receiving node creates a CRC from the bits in the frame to compare to the CRC value in the frame trailer. If these two CRC calculations match, the frame can be trusted as being received without error. The trusted frame will then be processed. A frame received with bad, nonmatching CRC's will be discarded.
14 bytes for the header and 4 bytes for the FCS (Frame Check Sequence) for a total of 18 bytes.
frame check sequence field
header trailer Data
An Ethernet frame has a 14 byte header, a data section, and a 4 byte trailer 14 byte header consist of destination address, source address and type The trailer is for CRC (Cyclic redundancy Check) An Ethernet frame can contain an IP and TCP PDU. IP header most important parts consists of (Version,IHL, Total length,Protocol, source and destination address) In details (Version,Header length,Differentiated services field, total Length, Identification, Flags, fragment offset, Time to live, protocol, header checksum, source and destination address). TCP header most important parts consists of (Source port, Destination port and header Length) In details (Source Port, Destination Port, Sequence number, Acknowledgment number, Header length,Flags,Window and check sum). The details of the IP and TCP header have been taken from a Network protocol Analyzer Wireshark on my own pc.
--CORRECTION--from Network+ Guide To Networks, fifth edition. This marks the end of the frame. The "trailer" indicates the frame check sequence number. It is used for error control in a frame.
Error detection at data link level is achieved by using a Frame Check Sequence (FCS) method like Parity, Checksum Calculation or Cyclic Redundancy Check (CRC).
Frame Check Sequence
frame check sequence. Network + Guide To Networks Review Question Chapter 6 #11
the ethernet frame what it concist of
c) Check frame sequence. The FCS (4 bytes in length) field is used to detect errors in a frame
Each Ethernet frame contains a trailer with a cyclic redundancy check (CRC) of the frame contents. After reception of a frame, the receiving node creates a CRC from the bits in the frame to compare to the CRC value in the frame trailer. If these two CRC calculations match, the frame can be trusted as being received without error. The trusted frame will then be processed. A frame received with bad, nonmatching CRC's will be discarded.
The FCS (Frame Check Sequence) Component of an ethernet frame permits the end recipient to check for, and correct, errors in the packet. It is a checksum that is checked against the packet for data integrity, to put it simply. When the number does not check out properly, the frame is thrown out and a replacement packet is requested.
The information found in the Ethernet frame trailer would be the error checking code.
The vin is generally stamped into the trailer tongue frame or stamped on a metal plate that is welded to the trailer tongue frame.
Frame Header - Network Header - Transport Header - Data - Frame Trailer
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