Network segment

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A network segment is a portion of a computer network. The nature and extent of a segment depends on the nature of the network and the device or devices used to interconnect end stations. [1]

Contents

Ethernet

According to the defining IEEE 802.3 standards for Ethernet, a network segment is an electrical connection between networked devices using a shared medium. [2] In the original 10BASE5 and 10BASE2 Ethernet varieties, a segment would therefore correspond to a single coax cable and all devices tapped into it. At this point in the evolution of Ethernet, multiple network segments could be connected with repeaters (in accordance with the 5-4-3 rule for 10 Mbit Ethernet) to form a larger collision domain.

With twisted-pair Ethernet, electrical segments can be joined together using repeaters or repeater hubs as can other varieties of Ethernet. This corresponds to the extent of an OSI layer 1 network and is equivalent to the collision domain. [3] [4] The 5-4-3 rule applies to this collision domain.

Using switches or bridges, multiple layer-1 segments can be combined to a common layer-2 segment, i.e. all nodes can communicate with each other through MAC addressing or broadcasts. A layer-2 segment is equivalent to a broadcast domain. Traffic within a layer-2 segment can be separated into virtually distinct partitions by using VLANs. Each VLAN forms its own logical layer-2 segment.

IP

A layer-3 segment in an IP network is called a subnetwork, formed by all nodes sharing the same network prefix as defined by their IP addresses and the network mask. [5] Communication between layer-3 subnets requires a router. Hosts on a subnet communicate directly using the layer-2 segment that connects them. Most often a subnetwork corresponds exactly with the underlying layer-2 segment but it is also possible to run multiple subnets on a single layer-2 segment.

Related Research Articles

A broadcast domain is a logical division of a computer network, in which all nodes can reach each other by broadcast at the data link layer. A broadcast domain can be within the same LAN segment or it can be bridged to other LAN segments.

Ethernet Computer networking technology

Ethernet is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3. Ethernet has since been refined to support higher bit rates, a greater number of nodes, and longer link distances, but retains much backward compatibility. Over time, Ethernet has largely replaced competing wired LAN technologies such as Token Ring, FDDI and ARCNET.

Wireless LAN Computer network that links devices using wireless communication within a limited area

A wireless LAN (WLAN) is a wireless computer network that links two or more devices using wireless communication to form a local area network (LAN) within a limited area such as a home, school, computer laboratory, campus, or office building. This gives users the ability to move around within the area and remain connected to the network. Through a gateway, a WLAN can also provide a connection to the wider Internet.

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

Carrier-sense multiple access with collision detection (CSMA/CD) is a medium access control (MAC) method used most notably in early Ethernet technology for local area networking. It uses carrier-sensing to defer transmissions until no other stations are transmitting. This is used in combination with collision detection in which a transmitting station detects collisions by sensing transmissions from other stations while it is transmitting a frame. When this collision condition is detected, the station stops transmitting that frame, transmits a jam signal, and then waits for a random time interval before trying to resend the frame.

Network topology Arrangement of the elements of a communication network

Network topology is the arrangement of the elements of a communication network. Network topology can be used to define or describe the arrangement of various types of telecommunication networks, including command and control radio networks, industrial fieldbusses and computer networks.

In telecommunications and computer networks, a channel access method or multiple access method allows more than two terminals connected to the same transmission medium to transmit over it and to share its capacity. Examples of shared physical media are wireless networks, bus networks, ring networks and point-to-point links operating in half-duplex mode.

A virtual local area network (VLAN) is any broadcast domain that is partitioned and isolated in a computer network at the data link layer. In this context, virtual, refers to a physical object recreated and altered by additional logic, within the local area network. VLANs work by applying tags to network frames and handling these tags in networking systems – creating the appearance and functionality of network traffic that is physically on a single network but acts as if it is split between separate networks. In this way, VLANs can keep network applications separate despite being connected to the same physical network, and without requiring multiple sets of cabling and networking devices to be deployed.

In the IEEE 802 reference model of computer networking, the logical link control (LLC) data communication protocol layer is the upper sublayer of the data link layer of the seven-layer OSI model. The LLC sublayer acts as an interface between the media access control (MAC) sublayer and the network layer.

The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer. The data link layer provides the functional and procedural means to transfer data between network entities and may also provide the means to detect and possibly correct errors that can occur in the physical layer.

KNX (standard) Standard in building automation

KNX is an open standard for commercial and domestic building automation. KNX devices can manage lighting, blinds and shutters, HVAC, security systems, energy management, audio video, white goods, displays, remote control, etc. KNX evolved from three earlier standards; the European Home Systems Protocol (EHS), BatiBUS, and the European Installation Bus. It can use twisted pair, powerline, RF, or IP links. On this network, the devices form distributed applications and tight interaction is possible. This is implemented via interworking models with standardised datapoint types and objects, modelling logical device channels.

A collision domain is a network segment connected by a shared medium or through repeaters where simultaneous data transmissions collide with one another. The collision domain applies particularly in wireless networks, but also affected early versions of Ethernet. A network collision occurs when more than one device attempts to send a packet on a network segment at the same time. Members of a collision domain may be involved in collisions with one another. Devices outside the collision domain do not have collisions with those inside.

Medium access control Service layer in IEEE 802 network standards

In IEEE 802 LAN/MAN standards, the medium access control sublayer is the layer that controls the hardware responsible for interaction with the wired, optical or wireless transmission medium. The MAC sublayer and the logical link control (LLC) sublayer together make up the data link layer. Within the data link layer, the LLC provides flow control and multiplexing for the logical link, while the MAC provides flow control and multiplexing for the transmission medium.

A multilayer switch (MLS) is a computer networking device that switches on OSI layer 2 like an ordinary network switch and provides extra functions on higher OSI layers. The MLS was invented by engineers at Digital Equipment Corporation.

Service set (802.11 network) Group of all devices on the same wireless network

In IEEE 802.11 wireless local area networking standards, a service set is a group of wireless network devices which share a service set identifier (SSID)—typically the natural language label that users see as a network name. A service set forms a logical network of nodes operating with shared link-layer networking parameters; they form one logical network segment.

Ethernet hub Device for interconnecting Ethernet devices

An Ethernet hub, active hub, network hub, repeater hub, multiport repeater, or simply hub is a network hardware device for connecting multiple Ethernet devices together and making them act as a single network segment. It has multiple input/output (I/O) ports, in which a signal introduced at the input of any port appears at the output of every port except the original incoming. A hub works at the physical layer of the OSI model. A repeater hub also participates in collision detection, forwarding a jam signal to all ports if it detects a collision. In addition to standard 8P8C ("RJ45") ports, some hubs may also come with a BNC or an Attachment Unit Interface (AUI) connector to allow connection to legacy 10BASE2 or 10BASE5 network segments.

Network bridge Device that creates a larger computer network from two smaller networks

A network bridge is a computer networking device that creates a single, aggregate network from multiple communication networks or network segments. This function is called network bridging. Bridging is distinct from routing. Routing allows multiple networks to communicate independently and yet remain separate, whereas bridging connects two separate networks as if they were a single network. In the OSI model, bridging is performed in the data link layer. If one or more segments of the bridged network are wireless, the device is known as a wireless bridge.

Computer network Network that allows computers to share resources and communicate with each other

A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are made up of telecommunication network technologies, based on physically wired, optical, and wireless radio-frequency methods that may be arranged in a variety of network topologies.

Shortest Path Bridging (SPB), specified in the IEEE 802.1aq standard, is a computer networking technology intended to simplify the creation and configuration of networks, while enabling multipath routing.

The 5-4-3 rule, also referred to as the IEEE way, is a design guideline for Ethernet computer networks covering the number of repeaters and segments on shared-medium Ethernet backbones in a tree topology. It means that in a collision domain there should be at most 5 segments tied together with 4 repeaters, with up to 3 mixing segments. Link segments can be 10BASE-T, 10BASE-FL or 10BASE-FB. This rule is also designated the 5-4-3-2-1 rule with there being two link segments and one collision domain.

References

  1. ↑ "Network Segment Definition". 2 October 2005. Retrieved 3 September 2010.
  2. ↑ "1.4.318", 802.3-2008 Part 3: Carrier sense multiple access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications, IEEE, 26 December 2008, segment: The medium connection, including connectors, between Medium Dependent Interfaces (MDIs) in a CSMA/CD local area network.
  3. ↑ "Segment (Network)" . Retrieved 3 September 2010.
  4. ↑ "Segment" . Retrieved 3 September 2010.
  5. ↑ "What is a Network Segment?" . Retrieved 3 September 2010.
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