SNAP header

The Sub-Network Attachment Point header (SNAP header) is an IEEE-defined layer 2 encapsulation header format for Ethernet and similar network packets. It is used at the logical link control layer of the IEEE 802.3 communications protocol stack, as a trailer to the IEEE-defined ARP and IP packet encapsulation, the Organization Code is set to zero, and the EtherType information is stored in the 16-bit Local Code field.

Thus, the LLC/SNAP headers are 8 bytes long in total. This reduces the size of the available payload for protocols such as the Internet Protocol to 1492 bytes, compared to the use of the J. Postel and J. Reynolds, A Standard for the Transmission of IP Datagrams over IEEE 802 Networks, []

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