IEEE 802.3

Az IEEE 802.3 egy szabvány gyűjtemény, ami az IEEE szabványokkal meghatározott Ethernet kábelezéssel megvalósított fizikai rétegnek és adatkapcsolati rétegnek megvalósításait tartalmazza. 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".

A 802.3 verziók

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:

Ethernet szabvány	Dátum	Meghatározás
Kísérleti Ethernet	1972 (1978-ben szabadalmaztatták)	2.94 Mbit/s (367 KB/s) koaxiális kábelen kábel busz
Ethernet II (DIX v2.0)	1982	10 Mbit/s (1.25 MB/s) vékony (thin) koaxiális kábelen (thinnet) - A keretekben van Típus (Type) mező. Ez a keretformátum használatos az Internet protocol suite minden Ethernetes formájánál.
IEEE 802.3	1983	10BASE5 10 Mbit/s (1.25MB/s) vastag koaxiális kábelen - azonos a DIX-el, kivéve, hogy a Típus (Type) mezőt a Hossz (Length) helyettesíti, és egy 802.2 LLC keret követi a 802.3 "header"-t
802.3a	1985	10BASE2 10 Mbit/s (1.25 MB/s) vékony koaxiális kábelen (thinnet vagy cheapernet)
802.3b	1985	10BROAD36
802.3c	1985	10 Mbit/s (1.25 MB/s) repeater
802.3d	1987	FOIRL (Fiber-Optic Inter-Repeater Link)
802.3e	1987	1BASE5 vagy StarLAN
802.3i	1990	10BASE-T 10 Mbit/s (1.25 MB/s) csavart érpáron
802.3j	1993	10BASE-F 10 Mbit/s (1.25 MB/s) optikai szálon
802.3u	1995	100BASE-TX, 100BASE-T4, 100BASE-FX Fast Ethernet 100 Mbit/s-re (12.5 MB/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 (12.5 MB/s) alacsony minőségű csavart érpáron
802.3z	1998	1000BASE-X Gbit/s Ethernet over Fibre-Optic at 1 Gbit/s (125 MB/s)
802.3-1998	1998	A revision of base standard incorporating the above admendments and errata
802.3ab	1999	1000BASE-T Gbit/s Ethernet over twisted pair at 1 Gbit/s (125 MB/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
802.3-2002	2002	A revision of base standard incorporating the three prior admendments and errata
802.3ae	2003	10 Gbit/s (1,250 MB/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 (1,250 MB/s) Ethernet over twin-axial cable
802.3-2005	2005	A revision of base standard incorporating the four prior admendments and errata.
802.3an	in work	10GBASE-T 10 Gbit/s (1,250 MB/s) Ethernet over unshielded twisted pair(UTP)
802.3ap	in work	Backplane Ethernet (1 and 10 Gbit/s (125 and 1,250 MB/s) over printed circuit boards)
802.3aq	in work	10GBASE-LRM 10 Gbit/s (1,250 MB/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: 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.

Lásd még

• IEEE 802
• IEEE 802.1, a hálózati architektúra
• IEEE 802.11, the corresponding set of Wireless Ethernet standards

External links

• http://www.ieee802.org/3/ -- The IEEE 802.3 Working Group
• Get IEEE 802.3 LAN/MAN CSMA/CD Access Method -- Download 802.3 specifications.