IEEE 802.3 is a collection of IEEE standards defining the physical layer and 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 ISO/IEC 8802-3 ANSI/IEEE 802.3 Standards refer to MAC sub-layer frames consisting of the Destination Address, Source Address, Length/Type, data, 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".
Versions of 802.3
The original Ethernet is called "Experimental Ethernet" today. It was developed by Bob Metcalfe 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:
|Experimental Ethernet||1972 (patented 1978)||2.94 Mbit/s over coaxial cable (coax) cable bus|
|Ethernet II (DIX v2.0)||1982||10 Mbit/s over thin coax (thinnet) - Frames have a Type field. The Internet protocol suite use this frame format on any media.|
|IEEE 802.3||1983||10BASE5 10 Mbit/s over thick coax - same as DIX except Type field is replaced by Length and LLC fields|
|802.3a||1985||10BASE2 10 Mbit/s over thin Coax (thinnet or cheapernet)|
|802.3c||1985||10 Mbit/s repeater specs|
|802.3d||1987||FOIRL (Fiber-Optic Inter-Repeater Link)|
|802.3e||1987||1BASE5 or StarLAN|
|802.3i||1990||10BASE-T 10 Mbit/s over twisted pair|
|802.3j||1993||10BASE-F 10 Mbit/s over Fiber-Optic|
|802.3u||1995||100BASE-TX, 100BASE-T4, 100BASE-FX Fast Ethernet at 100 Mbit/s (w/Auto-Negotiation)|
|802.3x||1997||Full Duplex and flow control; also incorporates DIX framing, so there's no longer a DIX/802.3 split|
|802.3y||1998||100BASE-T2 100 Mbit/s over low quality twisted pair|
|802.3z||1998||1000BASE-X Gbit/s Ethernet over Fibre-Optic at 1 Gbit/s|
|802.3ab||1999||1000BASE-T Gbit/s Ethernet over twisted pair at 1 Gbit/s|
|802.3ac||1998||Max frame size extended to 1522 bytes (to allow "Q-tag") The Q-tag includes 802.1Q VLAN information and 802.1p priority information.|
|802.3ad||2000||Link aggregation for parallel links|
|802.3ae||2003||10 Gbit/s Ethernet over fiber; 10GBASE-SR, 10GBASE-LR, 10GBASE-ER, 10GBASE-SW, 10GBASE-LW, 10GBASE-EW|
|802.3af||2003||Power over Ethernet|
|802.3ah||2004||Ethernet in the First Mile|
|802.3ak||2004||10GBASE-CX4 10 Gbit/s Ethernet over twin-axial cable|
|802.3an||in work||10GBASE-T 10 Gbit/s Ethernet over unshielded twisted pair(UTP)|
|802.3ap||in work||Backplane Ethernet (1 and 10 Gbit/s over printed circuit boards)|
|802.3aq||in work||10GBASE-LRM 10 Gbit/s Ethernet over multimode fiber|
|802.3ar||in work||Congestion management|
|802.3as||in work||Frame expansion|
What is defined in earlier IEEE 802.3 standards is often confused for what is used in practice: almost any network frame you can find on a LAN will be an Ethernet II frame, 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 Ethernet II frames are also valid 802.3 frames in 802.3x-1997 and later versions of the IEEE 802.3 Ethernet standard.