What is the IEEE standard for Ethernet

IEEE 802.3 / Ethernet basics

Ethernet is a family of network technologies that are mainly used in local networks (LAN), but also to connect large networks (WAN).
There are a number of standards for Ethernet, for which the Institute of Electrical and Electronics Engineers (IEEE) is responsible.

The original concept of Ethernet was to network office equipment. Ethernet is now synonymous with a local network. The specifications proposed and standardized under the 802.3 working group encompass a large number of variants and use cases.

  • Ethernet for LAN in homes and data centers
  • Carrier Ethernet for MAN and WAN
  • Industrial Ethernet for production environments
  • Ethernet in vehicles

Classification in the OSI layer model

2802.1
Internet working
802.2
Logical Link Control (LLC)
802.1
Media Access Control (MAC)
1802.3
Ethernet
802.4
Token bus
802.5
Token ring
802.11
Wireless LAN

In the case of Ethernet, one speaks of a packet-switching network technology whose standards on layers 1 and 2 of the OSI layer model define the addressing and access control to different transmission media. The user data already come in data packets from the protocols above. For example from TCP / IP. These data packets are provided with a header and then transmitted in the Ethernet network.
The Ethernet standards on OSI layer 2 are the LLC and MAC sublayers. They are independent of Ethernet and are also used for other transmission technologies. For example Bluetooth (IEEE 802.15) or WLAN (IEEE 802.11).

All Ethernet variants have one thing in common: They are based on the same principles that were originally defined in the 802.1, 802.2 and 802.3 standards. Ethernet is standardized under 802.3 and is based on 802.1 and 802.2.

Historical background

Ethernet was originally developed in the 1970s at PARC (Palo Alto Research Center), the research laboratory of the Xerox company. In cooperation with the companies DEC and Intel, Ethernet later became an open standard. This standard then formed the basis for the official 802.3 standard of the IEEE (Institute of Electrical and Electronics Engineers).

In addition to Ethernet, there were several networking technologies. For example Token Ring (based on coaxial cable) and FDDI (based on fiber optic cable). At some point in the 1990s, Ethernet caught on. In particular, the simple and cost-effective structure of an Ethernet network ensured that it spread rapidly all over the world. Arcnet, Token Ring, FDDI or even ATM and SDH are hardly mentioned any more. Today almost all networks in the LAN and WAN are implemented with Ethernet technology.

Technical background

One of the forerunners of Ethernet was a wireless network called ALOHA that linked the Hawaiian Islands. Here the transmission medium was air (ether or ether). Ethernet was developed to allow many hosts to share a transmission medium. While there was no air for ALOHA, a coaxial cable was chosen as the transmission medium for Ethernet, which connected the computers to one another in a bus topology.
For transmission technology, this means that there is only one transmission channel that only one can use. An access method or transmission protocol must therefore work according to the Listen-Before-Talk (LBT) principle.
It all started in the 1980s with 10 megabit Ethernet over coaxial cable. Various further developments followed for twisted pair cables and fiber optic cables with lower and higher transmission rates on longer and shorter cables.

Transmission medium and network topology

The original Ethernet is based on a coaxial cable as the transmission medium. Several stations were connected one behind the other to form a chain with a cable. The network topology has been referred to as a bus.
Further Ethernet variants for backplanes, twinax cables, fiber optics and twisted pairs were later developed.

The decisive breakthrough of Ethernet in the LAN came with the change from shared to switched media (from bus to star topology) in connection with structured cabling. At the same time, the consistent backward compatibility has meant that investments remain sustainable to a certain extent. Old components for 10 and 100 Mbit / s can be combined with components for 1 Gbit / s. In case of doubt, all you need is a media converter.

Transmission technology

Ethernet transports data in packets without a fixed access grid. This distinguishes Ethernet from other packet-oriented systems, which can guarantee each participant a minimum bandwidth with a fixed time frame. This is why Ethernet poses problems for all types of time-critical applications. With Ethernet there is no guarantee that the data will reach the recipient within a certain time. This means that the success of a transfer is not certain. It is only subject to a certain probability. Ethernet components discard data packets if there is not enough bandwidth available.
Because of the unreliable transmission technology, Ethernet is dependent on error handling of higher protocols. This is also one of the reasons why other networking techniques are still preferred in certain areas today. In comparison, Ethernet is a networking technology that is easy to implement and has proven itself and established itself over decades in local networks.

Transmission speed

The actual transmission speed (net data rate) of Ethernet depends on the speed level and the TCP connection quality.

  • Fast Ethernet with 100 Mbit / s achieves just under 0.094 Gbit / s, i.e. approx. 10 Mbyte / s.
  • With Gigabit Ethernet with 1 GBit / s you reach almost 0.94 GBit / s, i.e. approx. 100 MByte / s.
  • With Gigabit Ethernet with 2.5 GBit / s you can achieve almost 2.4 GBit / s, i.e. almost 300 MByte / s.
  • With Gigabit Ethernet with 10 GBit / s you get a net 9.4 GBit / s, i.e. a little over 1,100 MByte / s.

These speed specifications roughly correspond to the throughputs to be expected for HTTP connections, FTP downloads and Windows shares.
The difference between the gross and net data rate is added to the protocol headers on layers 2 and 3.

For comparison, the transmission speed of PC interfaces:

  • USB 2.0: approx. 40 MB / s
  • USB 3.0: approx. 450 MB / s
  • SATA hard disks: approx. 500 MB / s
  • PCIe SSDs: over 3,000 MB / s

Extensions

Extensions transform the initially collision-prone transmission protocol into a safe, redundant, versatile and fast networking technology.

  • Energy Efficient Ethernet (EEE)
  • high resolution time synchronization (IEEE 1588v2)
  • Encryption at MAC level (MACSec)
  • Power supply up to 100 watts (PoE)
  • Trunking or link aggregation
  • Transmission on just one wire pair (single pair)
  • Use as a fieldbus
  • Storage connection

Overview: Ethernet technology

Overview: standards and transmission speed

Other Ethernet standards:

Other related topics:

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