Ethernet

A twisted pair cable with an 8P8C modular connector attached to a laptop computer, used for Ethernet
An Ethernet-over-twisted-pair port
Symbol used by Apple on some devices to denote an Ethernet connection.
Accton Etherpocket-SP parallel port Ethernet adapter (circa 1990). Supports both coaxial (10BASE2) and twisted pair (10BASE-T) cables. Power is drawn from a PS/2 port passthrough cable.
An Intel 82574L Gigabit Ethernet NIC, PCI Express ×1 card
Older Ethernet equipment. Clockwise from top-left: An Ethernet transceiver with an in-line 10BASE2 adapter, a similar model transceiver with a 10BASE5 adapter, an AUI cable, a different style of transceiver with 10BASE2 BNC T-connector, two 10BASE5 end fittings (N connectors), an orange "vampire tap" installation tool (which includes a specialized drill bit at one end and a socket wrench at the other), and an early model 10BASE5 transceiver (h4000) manufactured by DEC. The short length of yellow 10BASE5 cable has one end fitted with an N connector and the other end prepared to have an N connector shell installed; the half-black, half-grey rectangular object through which the cable passes is an installed vampire tap.
A 1990s ISA network interface card supporting both coaxial-cable-based 10BASE2 (BNC connector, left) and twisted-pair-based 10BASE-T (8P8C connector, right)
Patch cables with patch fields of two Ethernet switches
A core Ethernet switch
A close-up of the SMSC LAN91C110 (SMSC 91x) chip, an embedded Ethernet chip
The original Ethernet implementation: shared medium, collision-prone. All computers trying to communicate share the same cable, and so compete with each other.
Modern Ethernet implementation: switched connection, collision-free. Each computer communicates only with its own switch, without competition for the cable with others.

Family of wired computer networking technologies commonly used in local area networks , metropolitan area networks (MAN) and wide area networks (WAN).

- Ethernet

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Network switch

Networking hardware that connects devices on a computer network by using packet switching to receive and forward data to the destination device.

Avaya ERS 2550T-PWR, a 50-port Ethernet switch
A modular network switch with three network modules (a total of 24 Ethernet and 14 Fast Ethernet ports) and one power supply.
A 5-port layer-2 switch without management functionality
A rack-mounted 24-port 3Com switch
A couple of managed D-Link Gigabit Ethernet rackmount switches, connected to the Ethernet ports on a few patch panels using Category 6 patch cables (all equipment is installed in a standard 19-inch rack)

Switches for Ethernet are the most common form of network switch.

Ethernet over twisted pair

8P8C modular plug pin positioning
Cat 6A cable with an M12X connector in one end and a modular connector in the other.
Comparison of twisted-pair-based Ethernet technologies

Ethernet over twisted-pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network.

Token Ring

Computer networking technology used to build local area networks.

Two examples of Token Ring networks: a) Using a single MAU b) Using several MAUs connected to each other
Token Ring network
Token Ring network: operation of a MAU explained
IBM hermaphroditic connector with locking clip. Screen connectors are prominently visible, gold-plated signal connectors less so.
The IBM 8228 Multistation Access Unit with accompanying Setup Aid to prime the relays on each port
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Both Token Ring and Ethernet interfaces on the 2210-24M
100 Mbit/s IBM Token Ring Management Adapter with Wake On LAN. Both UTP (RJ45) and STP (IBM Data Connector) interfaces are present.
Assorted full-length Micro Channel Token Ring cards, including a LANStreamer which features multiple RJ45 ports for usage in a Token Ring network.
Token Ring Network Interface Cards (NICs) with varying interfaces from: ISA, PCI and MicroChannel
Madge 4/16Mbit/s TokenRing ISA NIC
A series of multiple 16/4 early Micro Channel Token Ring cards which would have prominently been installed in many Personal System/2 machines.
IBM Data Connectors on the IBM 8228 Multistation Access Unit.
8P8C 'Media Filters' that plug into an IBM Data Connector converting it for use with 8P8C connectors.

Token Ring was a successful technology, particularly in corporate environments, but was gradually eclipsed by the later versions of Ethernet.

MAC address

Unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment.

Label of a UMTS router with MAC addresses for LAN and WLAN modules
The structure of a 48-bit MAC address. The b0 bit distinguishes multicast and unicast addressing and the b1 bit distinguishes universal and locally administered addressing.

This use is common in most IEEE 802 networking technologies, including Ethernet, Wi-Fi, and Bluetooth.

Data link layer

Second layer of the seven-layer OSI model of computer networking.

Communication in the OSI-Model (example with layers 3 to 5)

Examples of data link protocols are Ethernet, Point-to-Point Protocol (PPP), HDLC and ADCCP.

Coaxial cable

RG-59.jpg flexible coaxial cable composed of:1.

In his 1880 British patent, Oliver Heaviside showed how coaxial cable could eliminate signal interference between parallel cables.
Coaxial cable cutaway (not to scale)
Schematic representation of the elementary components of a transmission line
Schematic representation of a coaxial transmission line, showing the characteristic impedance Z_0
RG-6 coaxial cable
RG-142 coaxial cable
RG-405 semi-rigid coaxial cable
High-end coaxial audio cable (S/PDIF)
1+5/8 in flexible line
1-5/8" Heliax coaxial cable
Semi-rigid coax assembly
Semi-rigid coax installed in an Agilent N9344C 20GHz spectrum analyser
Early coaxial antenna feedline of 50 kW radio station WNBC, New York, 1930s
AT&T coaxial cable trunkline installed between East Coast and Midwest in 1948. Each of the 8 coaxial subcables could carry 480 telephone calls or one television channel.

Its applications include feedlines connecting radio transmitters and receivers to their antennas, computer network (e.g., Ethernet) connections, digital audio (S/PDIF), and distribution of cable television signals.

IEEE 802.11

Part of the IEEE 802 set of local area network technical standards, and specifies the set of media access control (MAC) and physical layer (PHY) protocols for implementing wireless local area network (WLAN) computer communication.

This Linksys WRT54GS Wi-Fi router operates on the 2.4 GHz "g" standard, capable of transmitting 54 Mbit/s.
For comparison, this Netgear dual-band router from 2013 uses the "ac" standard, capable of transmitting 1900 Mbit/s (combined).
Graphical representation of Wi-Fi application specific (UDP) performance envelope 2.4 GHz band, with 802.11g. 1 Mbps = 1 Mbit/s
Graphical representation of Wi-Fi application specific (UDP) performance envelope 2.4 GHz band, with 802.11n with 40MHz
Graphical representation of Wi-Fi channels in the 2.4 GHz band
Spectral masks for 802.11g channels 1–14 in the 2.4 GHz band
802.11 non-overlapping channels for 2.4GHz. Covers 802.11b,g,n

The protocols are typically used in conjunction with IEEE 802.2, and are designed to interwork seamlessly with Ethernet, and are very often used to carry Internet Protocol traffic.

PARC (company)

Research and development company in Palo Alto, California.

PARC entrance
Xerox PARC in 1977
Xerox Alto

Xerox PARC has been at the heart of numerous revolutionary computer developments, including laser printing, Ethernet, the modern personal computer, graphical user interface (GUI) and desktop paradigm, object-oriented programming, ubiquitous computing, electronic paper, amorphous silicon (a-Si) applications, the computer mouse, and very-large-scale integration (VLSI) for semiconductors.

Local area network

Computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building.

A conceptual diagram of a local area network using bus network topology.
Twisted pair LAN cable

Ethernet and Wi-Fi are the two most common technologies in use for local area networks.

10BASE5

10BASE5 vampire tap Medium Attachment Unit (transceiver)
10BASE5 transceivers, cables, and tapping tool

10BASE5 (also known as thick Ethernet or thicknet) was the first commercially available variant of Ethernet.