For this reason, the start delimiter is made up of non-data symbols and zeros. Non-data symbols do not appear within the data portion of the frame. The frame must indicate which station on the shared medium it is intended for and which station it is sent from. This information is provided by the source and destination address fields. These addresses of physical stations on the medium are each 6 octets long.
Data follows the addresses.
Data must be in integral octets up to 8191 in length. The cable and the modem are susceptible to noise, which destroys the data being sent. To guard against frames with corrupted data, the Frame Check Sequence, FCS, is used. As the data bits in the frame are transmitted, the transmitting station calculates the FCS code. The FCS is attached to the end of the frame.