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IEEE 802.3 is a collection of IEEE standards defining the physical layer and the media access control (MAC) sublayer of the data link layer of wired Ethernet. This is generally a LAN technology with some WAN applications. Physical connections are made between nodes and/or infrastructure devices (hubs, switches, routers) by various types of copper or fiber cable. 802.3 is a technology that can support the IEEE 802.1 network architecture. The maximum packet size is 1518 bytes, although to allow the Q-tag for Virtual LAN and priority data in 802.3ac it is extended to 1522 bytes. If the upper layer protocol submits a PDU (Protocol data unit) less than 64 bytes, 802.3 will pad the data field to achieve the minimum 64 bytes. Although it is not technically correct, the terms "packet" and "frame" are used interchangeably. The The original Ethernet is called "Experimental Ethernet" today. It was developed by Robert Metcalfe in 1972 (patented in 1978) and was based in part on the wireless ALOHAnet protocol. It is not in use anywhere, but is thought to be the only Ethernet by some purists. The first "Ethernet" that was generally used outside Xerox was the DIX Ethernet. However, as DIX Ethernet was derived from Experimental Ethernet, and as many standards have been developed that are based on DIX Ethernet, the technical community has accepted the term Ethernet for all of them. Therefore, the term "Ethernet" can be used to name networks using any of the following standardized media and functions: What is defined in earlier IEEE 802.3 standards is often confused for what is used in practice: most network frames you will find on an Ethernet will be DIX frames, since the Internet protocol suite will use this format, with the type field set to the corresponding IETF protocol type. IEEE 802.3x-1997 allows the 16-bit field after the MAC addresses to be used as a type field or a length field, so that DIX frames are also valid 802.3 frames in 802.3x-1997 and later versions of the IEEE 802.3 Ethernet standard.
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