IEEE 802.3 is the IEEE standard defining the physical layer and transport layer of (a variant 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, although to allow the Virtual LAN tag 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 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".
Versions of Ethernet
This original Ethernet, today, is called "Experimental Ethernet". It is not in use anywhere, but is thought to be the only Ethernet by purists. However, as many standards have been developed that are based on Experimental Ethernet - the technical community has accepted the term Ethernet for all of them. Therefore, Ethernet can be used to name any of the following:
| Ethernet Standard |
Date |
Description |
| 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)
|
| 802.3b |
1985 |
10BROAD36 |
| 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 |
| 802.3y |
1998 |
100BASE-T2 100 Mbit/s over low quality twisted pair
|
| 802.3z |
1998 |
1000BASE-X Gigabit Ethernet over coax at 1 Gbit/s |
| 802.3ab |
1999 |
1000BASE-T Gigabit Ethernet over twisted pair at 1 Gbit/s
|
| 802.3ac |
1998 |
Max frame size extended to 1522 bytes (to allow VLAN tag)
|
| 802.3ad |
2000 |
Link aggregation for parallel links |
| 802.3ae |
2003 |
10 Gigabit Ethernet over fiber |
|
802.3af
|
2003 |
Power over Ethernet
|
| 802.3ah |
2004 |
Ethernet in the First Mile |
| 802.3ak |
2004 |
10GBASE-CX4 10 Gigabit Ethernet over twin-axial cable |
| 802.3an |
in work |
10GBASE-T 10 Gigabit Ethernet over twisted pair |
| 802.3ap |
in work |
Backplane Ethernet (1 and 10 Gb/sec over printed circuit boards)
|
| 802.3aq |
in work |
10GBASE-LRM 10 Gigabit Ethernet over multimode fiber |
| 802.3ar |
in work |
Congestion management
|
| 802.3as |
in work |
Frame expansion |
What is defined in the IEEE 802.3 standard 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.
See also
References
External links
- http://www.ieee802.org/3/ -- The IEEE 802.3 Working Group
