MACsec 802.1AE header (SecTAG)

The MACsec 802.1AE header includes a security TAG (SecTAG) field that contains the following:

• association number within the channel

• packet number to provide a unique initialization vector for encryption and authentication algorithms as well as protection against replay attack

• optional LAN-Wide secure channel identifier

The security field, which is identified by the MACsec Ethertype, conveys the following information:

• TAG Control Information (TCI)

• Association Number (AN)

• Short Length (SL)

• Packet Number (PN)

• Optionally-encoded Secure Channel Identifier (SCI)

Figure: SecTAG format shows the format of the SecTAG.

Figure: SecTAG format