стандарт IEEE 802.3 смотри 802.3
The IEEE standard defining the hardware layer and transport layer of (a varient of) Ethernet. The maximum segment length is 500m and the maximum total length is 2.5km. The maximum number of hosts is 1024. The maximum packet size is 1518 bytes. If the upper layer protocol submits a PDU less than 64 bytes, 802.3 will pad the LLC Info field to achieve the minimum 64 bytes. Although it is not technically correct, the terms "packet" and frame are used interchangeably. The ISO/IEC 8802-3 ANSI/IEEE 802.3 Standards refer to MAC sub-layer frames consisting of the Destination Address, Source Address, Length, LLC Info., and FCS fields. The Preamble and SFD are (usually) considered a header to the MAC Frame. This header plus the MAC Frame constitute a "Packet".