Controlling false packet acceptance

A method comprising:

• receiving from a network device, at a physical coding sublayer (PCS) unit in a network interface of a transmitting device, an Ethernet packet;
• encoding, by the PCS unit using a 64B/66B line code, the Ethernet packet into a transmission frame, wherein the transmission frame includes (i) a first set of bit fields corresponding to contents of the Ethernet packet, and (ii) a second set of bit fields forming a terminating block of the transmission frame and including control information for the 64B/66B encoding;
• computing, by the PCS unit, a validity value of the transmission frame, wherein the validity value includes a length value of the transmission frame, and wherein the length value indicates a number of bits in the first set of bit fields included in the transmission frame;
• inserting, by the PCS unit, the validity value into the second set of bit fields of the terminating block, wherein the second set of bit fields in the terminating block includes a type bit field, and wherein insertion of the validity value into the second set of bit fields comprises
• determining a position of a 64B/66B end of packet (EOP) bit field in the terminating block, and
• inserting the validity value into one or more idle bit fields that are adjacent to the 64B/66B EOP bit field in the terminating block, wherein the inserting of the validity value into the one or more idle bit fields comprises updating the type bit field in the terminating block to indicate adjusted location of the 64B/66B EOP bit field in the terminating block;
• processing, by the PCS unit, the transmission frame for sending to a receiving device over a physical medium;
• and
• transmitting the transmission frame from the network device to the receiving device to enable the receiving device to (i) perform a validity check on the transmission frame based on the length value, and (ii) accept the frame based on the validity check.

A network device comprising:

• a network interface that includes a physical coding sublayer (PCS) unit, wherein the PCS unit is configured to
• receive an Ethernet packet,
• encode, using 64B/66B line code, the Ethernet packet into a transmission frame, wherein the transmission frame includes (i) a first set of bit fields corresponding to contents of the Ethernet packet, and (ii) a second set of bit fields forming a terminating block of the transmission frame and including control information for the 64B/66B encoding,
• compute a validity value of the transmission frame including computing a length value of the transmission frame, wherein the length value is encoded as 14-bit data or 16-bit data,
• insert the validity value into the second set of bit fields of the terminating block, wherein insertion of the validity value into the second set of bit fields comprises
• determining a position of a 64B/66B end of packet (EOP) bit field in the terminating block, and
• inserting the validity value into one or more idle bit fields that are adjacent to the 64B/66B EOP bit field including inserting the length value into two of the one or more idle bit fields,
• process the transmission frame for sending to a receiving device over a physical medium;
• and
• transmitting the transmission frame from the network device to the receiving device to enable the receiving device to (i) perform a validity check on the transmission frame based on the length value, and (ii) accept the frame based on the validity check.