1.
Crossover cable
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A crossover cable connects two devices of the same type, for example DTE-DTE or DCE-DCE, usually connected asymmetrically, by a modified cable called a crosslink. Such distinction of devices was introduced by IBM. e, pCs, linking two or more hubs, switches or routers together, possibly to work as one wider device. Null modem of RS-232 Ethernet crossover cable Rollover cable A loopback is a type of degraded one side crosslinked connection connecting a port to itself, usually for test purposes. A T1 cable uses T568B pairs 1 and 2, so to connect two T1 CSU/DSU devices back-to-back requires a cable that swaps these pairs. Specifically, pins 1,2,4, and 5 are connected to 4,5,1, a 56K DDS cable uses T568B pairs 02 and 04, so a crossover cable for these devices swaps those pairs. Electrical connector wiring Pinout Structured cabling TIA/EIA-568-B
2.
Ethernet
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Ethernet /ˈiːθərnɛt/ is a family of computer networking technologies commonly used in local area networks, metropolitan area networks and wide area networks. It was commercially introduced in 1980 and first standardized in 1983 as IEEE802.3, over time, Ethernet has largely replaced competing wired LAN technologies such as token ring, FDDI and ARCNET. The original 10BASE5 Ethernet uses coaxial cable as a medium, while the newer Ethernet variants use twisted pair. Over the course of its history, Ethernet data transfer rates have increased from the original 2.94 megabits per second to the latest 100 gigabits per second. The Ethernet standards comprise several wiring and signaling variants of the OSI physical layer in use with Ethernet, systems communicating over Ethernet divide a stream of data into shorter pieces called frames. As per the OSI model, Ethernet provides services up to, since its commercial release, Ethernet has retained a good degree of backward compatibility. Features such as the 48-bit MAC address and Ethernet frame format have influenced other networking protocols, the primary alternative for some uses of contemporary LANs is Wi-Fi, a wireless protocol standardized as IEEE802.11. Ethernet was developed at Xerox PARC between 1973 and 1974 and it was inspired by ALOHAnet, which Robert Metcalfe had studied as part of his PhD dissertation. In 1975, Xerox filed a patent application listing Metcalfe, David Boggs, Chuck Thacker, in 1976, after the system was deployed at PARC, Metcalfe and Boggs published a seminal paper. Metcalfe left Xerox in June 1979 to form 3Com and he convinced Digital Equipment Corporation, Intel, and Xerox to work together to promote Ethernet as a standard. The so-called DIX standard, for Digital/Intel/Xerox, specified 10 Mbit/s Ethernet, with 48-bit destination and source addresses and it was published on September 30,1980 as The Ethernet, A Local Area Network. Data Link Layer and Physical Layer Specifications, version 2 was published in November,1982 and defines what has become known as Ethernet II. Formal standardization efforts proceeded at the time and resulted in the publication of IEEE802.3 on June 23,1983. Ethernet initially competed with two largely proprietary systems, Token Ring and Token Bus, in the process, 3Com became a major company. 3Com shipped its first 10 Mbit/s Ethernet 3C100 NIC in March 1981, an Ethernet adapter card for the IBM PC was released in 1982, and, by 1985, 3Com had sold 100,000. Parallel port based Ethernet adapters were produced for a time, with drivers for DOS, by the early 1990s, Ethernet became so prevalent that it was a must-have feature for modern computers, and Ethernet ports began to appear on some PCs and most workstations. This process was sped up with the introduction of 10BASE-T and its relatively small modular connector. Since then, Ethernet technology has evolved to meet new bandwidth, in addition to computers, Ethernet is now used to interconnect appliances and other personal devices
3.
Network interface controller
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A network interface controller is a computer hardware component that connects a computer to a computer network. Early network interface controllers were commonly implemented on expansion cards that plugged into a computer bus, the low cost and ubiquity of the Ethernet standard means that most newer computers have a network interface built into the motherboard. The network controller implements the electronic circuitry required to communicate using a physical layer and data link layer standard such as Ethernet, Fibre Channel. The NIC allows computers to communicate over a network, either by using cables or wirelessly. Although other network technologies exist, IEEE802 networks including the Ethernet variants have achieved near-ubiquity since the mid-1990s, newer server motherboards may even have dual network interfaces built-in. The Ethernet capabilities are integrated into the motherboard chipset or implemented via a low-cost dedicated Ethernet chip. A separate network card is not required unless additional interfaces are needed or some type of network is used. The NIC may use one or more of the techniques to indicate the availability of packets to transfer. Interrupt-driven I/O is where the peripheral alerts the CPU that it is ready to transfer data, also, NICs may use one or more of the following techniques to transfer packet data, Programmed input/output is where the CPU moves the data to or from the NIC to memory. Direct memory access is where some other device other than the CPU assumes control of the bus to move data to or from the NIC to memory. This removes load from the CPU but requires more logic on the card, in addition, a packet buffer on the NIC may not be required and latency can be reduced. There are two types of DMA, third-party DMA in which a DMA controller other than the NIC performs transfers, an Ethernet network controller typically has an 8P8C socket where the network cable is connected. Older NICs also supplied BNC, or AUI connections, a few LEDs inform the user of whether the network is active, and whether or not data transmission occurs. Ethernet network controllers typically support 10 Mbit/s Ethernet,100 Mbit/s Ethernet, such controllers are designated as 10/100/1000, meaning that they can support a notional maximum transfer rate of 10,100 or 1000 Mbit/s. 10 Gigabit Ethernet NICs are also available, and, as of November 2014, are beginning to be available on computer motherboards, multiqueue NICs provide multiple transmit and receive queues, allowing packets received by the NIC to be assigned to one of its receive queues. The hardware-based distribution of the interrupts, described above, is referred to as receive-side scaling, purely software implementations also exist, such as the receive packet steering and receive flow steering. Examples of such implementations are the RFS and Intel Flow Director, with multiqueue NICs, additional performance improvements can be achieved by distributing outgoing traffic among different transmit queues. By assigning different transmit queues to different CPUs/cores, various operating systems internal contentions can be avoided and those NICs support, Accessing local and remote memory without involving the remote CPU
4.
Patch cable
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A patch cable or patch cord or patch lead is an electrical or optical cable used to connect one electronic or optical device to another for signal routing. Devices of different types are connected with patch cords, patch cords are usually produced in many different colors so as to be easily distinguishable, and are relatively short, perhaps no longer than two metres. However, patch cords typically refer only to short cords used with patch panels, patch cord cable differs from standard structured cabling cable in that patch cable is stranded for flexibility, whereas standard cable is solid copper. Because the patch cord is stranded copper construction the attenuation is higher on patch cords than solid cable so short lengths should be adhered to. Patch cords can be as short as 3 inches, to connect stacked components or route signals through a patch bay, as length increases, the cables are usually thicker and/or made with more shielding, to prevent signal loss and the introduction of unwanted radio frequencies and hum. Patch cords are made of coaxial cables, with the signal carried through a shielded core. Each end of the cable is attached to a connector so that the cord may be plugged in, connector types may vary widely, particularly with adapting cables. A pigtail is similar to a cord and is the informal name given to a cable fitted with a connector at one end. In the context of copper cabling, these cables are sometimes referred to as blunt patch cords, optical fiber pigtails, in contrast to copper pigtails, can be more accurately described as a connector than a cable or cord. A fiber pigtail is a single, short, usually tight-buffered, optical fiber that has an optical connector pre-installed on one end, the end of the fiber pigtail is stripped and fusion spliced to a single fiber of a multi-fiber trunk. Splicing of pigtails to each fiber in the trunk breaks out the cable into its component fibers for connection to the end equipment. A variety of cables are used to carry electrical signals in sound recording studios, microphones are typically connected to mixing boards or PA systems with XLR microphone cables which use three-pin XLR connectors. DJs using record players connect their turntables to mixers or PA systems with stereo RCA connectors, to resolve this problem, DJs can either use adapters or special cables. Heavier-gauge cables are used for carrying amplified signals from amplifiers to speakers, ¼ TRS phone connector cables can carry stereo signals, so they are used for stereo headphones and for some patching purposes. The patch bay is a panel of audio connectors where XLR cables. The cables could get tangled or mixed up, and it would be hard to know, when faced with 20 connectors at the end of the cable run, which cable was associated with which microphone or instrument. The patch bay is numbered, so that the engineer can note which microphone or instrument is plugged into each numbered connection, Cable management Crossover cable White Papers - Cable Anatomy
5.
Network switch
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A network switch is a computer networking device that connects devices together on a computer network by using packet switching to receive, process, and forward data to the destination device. Unlike less advanced network hubs, a network switch forwards data only to one or multiple devices that need to receive it, a network switch is a multiport network bridge that uses hardware addresses to process and forward data at the data link layer of the OSI model. Switches for Ethernet are the most common form and the first Ethernet switch was introduced by Kalpana in 1990, Switches also exist for other types of networks including Fibre Channel, Asynchronous Transfer Mode, and InfiniBand. A switch is a device in a network that electrically and logically connects together other devices. Multiple data cables are plugged into a switch to enable communication between different networked devices, Switches manage the flow of data across a network by transmitting a received network packet only to the one or more devices for which the packet is intended. Each networked device connected to a switch can be identified by its network address and this maximizes the security and efficiency of the network. Because broadcasts are still being forwarded to all connected devices, the newly formed network segment continues to be a broadcast domain, an Ethernet switch operates at the data link layer of the OSI model to create a separate collision domain for each switch port. In full duplex mode, each switch port can simultaneously transmit and receive, in the case of using a repeater hub, only a single transmission could take place at a time for all ports combined, so they would all share the bandwidth and run in half duplex. Necessary arbitration would result in collisions, requiring retransmissions. The network switch plays an role in most modern Ethernet local area networks. Mid-to-large sized LANs contain a number of linked managed switches, in most of these cases, the end-user device contains a router and components that interface to the particular physical broadband technology. User devices may include a telephone interface for Voice over IP protocol. Segmentation involves the use of a bridge or a switch to split a larger collision domain into smaller ones in order to reduce collision probability, in the extreme case, each device is located on a dedicated switch port. In contrast to an Ethernet hub, there is a separate collision domain on each of the switch ports and this allows computers to have dedicated bandwidth on point-to-point connections to the network and also to run in full-duplex without collisions. Full-duplex mode has one transmitter and one receiver per collision domain. Switches may operate at one or more layers of the OSI model, including the data link, a device that operates simultaneously at more than one of these layers is known as a multilayer switch. In switches intended for use, built-in or modular interfaces make it possible to connect different types of networks, including Ethernet, Fibre Channel, RapidIO, ATM. This connectivity can be at any of the layers mentioned, while the layer-2 functionality is adequate for bandwidth-shifting within one technology, interconnecting technologies such as Ethernet and token ring is performed easier at layer 3 or via routing
6.
Ethernet hub
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It has multiple input/output 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 layer of the OSI model. Repeater hubs also participate in collision detection, forwarding a jam signal to all if it detects a collision. In addition to standard 8P8C ports, some hubs may also come with a BNC or Attachment Unit Interface connector to allow connection to legacy 10BASE2 or 10BASE5 network segments, hubs are now largely obsolete, having been replaced by network switches except in very old installations or specialized applications. As of 2011, connecting network segments by repeaters or hubs is deprecated by IEEE802.3, a network hub is an unsophisticated device in comparison with a switch. As a multiport repeater it works by repeating bits received from one of its ports to all other ports. It is aware of physical layer packets, that is it can detect their start, a hub cannot further examine or manage any of the traffic that comes through it, any packet entering any port is rebroadcast on all other ports. A hub/repeater has no memory to store any data in – a packet must be transmitted while it is received or is lost when a collision occurs, due to this, hubs can only run in half duplex mode. Consequently, due to a larger collision domain, packet collisions are frequent in networks connected using hubs than in networks connected using more sophisticated devices. The need for hosts to be able to detect collisions limits the number of hubs, for 10 Mbit/s networks built using repeater hubs, the 5-4-3 rule must be followed, up to five segments are allowed between any two end stations. For 10BASE-T networks, up to five segments and four repeaters are allowed between any two hosts, for 100 Mbit/s networks, the limit is reduced to 3 segments between any two end stations, and even that is only allowed if the hubs are of Class II. Most hubs detect typical problems, such as collisions and jabbering on individual ports. Thus, hub-based twisted-pair Ethernet is generally more robust than coaxial cable-based Ethernet, to pass data through the repeater in a usable fashion from one segment to the next, the framing and data rate must be the same on each segment. This means that a repeater cannot connect an 802.3 segment,100 Mbit/s hubs and repeaters come in two different speed grades, Class I delay the signal for a maximum of 140 bit times and Class II hubs delay the signal for a maximum of 92 bit times. In the early days of Fast Ethernet, Ethernet switches were relatively expensive devices, hubs suffered from the problem that if there were any 10BASE-T devices connected then the whole network needed to run at 10 Mbit/s. Therefore, a compromise between a hub and a switch was developed, known as a dual-speed hub and these devices make use of an internal two-port switch, bridging the 10 Mbit/s and 100 Mbit/s segments. When a network device becomes active on any of the physical ports and this obviated the need for an all-or-nothing migration to Fast Ethernet networks. These devices are considered hubs because the traffic between devices connected at the speed is not switched
7.
Medium-dependent interface
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A medium dependent interface describes the interface in a computer network from a physical layer implementation to the physical medium used to carry the transmission. Ethernet over twisted pair also defines a medium dependent interface crossover interface, auto MDI-X ports on newer network interfaces detect if the connection would require a crossover, and automatically chooses the MDI or MDI-X configuration to properly match the other end of the link. The popular Ethernet family defines common medium dependent interfaces, for 10BASE5, connection to the coaxial cable was made with either a vampire tap or a pair of N connectors. For 10BASE2 the connection to the cable was typically made with a single BNC connector to which a T-piece was attached. For twisted pair cabling 8P8C modular connectors are used, for fiber a variety of connectors are used depending on manufacturer and physical space availability. With 10BASE-T and 100BASE-TX separate twisted pairs are used for the two directions of communication, since twisted pair cables are conventionally wired pin to pin there are two different pinouts used for the medium dependent interface. These are referred to as MDI and MDI-X, when connecting an MDI port to an MDI-X port a straight through cable is used while to connect two MDI ports or two MDI-X ports a crossover cable must be used. Conventionally MDI is used on end devices while MDI-X is used on hubs, some network hubs or switches have an MDI port to connect to other hubs or switches without a crossover cable. The terminology generally refers to variants of the Ethernet over twisted pair technology that use a female 8P8C port connection on a computer, the X refers to the fact that transmit wires on an MDI device must be connected to receive wires on an MDI-X device. Straight through cables connect pins 1 and 2 on an MDI device to pins 1 and 2 on an MDI-X device, similarly pins 3 and 6 are receive pins on an MDI device and transmit pins on an MDI-X device. The general convention was for network hubs and switches to use the MDI-X configuration, while all other such as personal computers, workstations. Some routers and other devices had a switch to go back. Thus, connecting MDI to MDI-X requires a straight-through cable, connecting MDI to MDI or MDI-X to MDI-X requires a crossover in the cable to get an odd number. When using more complicated setups through multiple patch panels in structured cabling and it is a good idea to have all necessary crossovers on one side, i. e. either on the central hub/switch or on each secondary hub/switch. The confusion of needing two different kinds of cables for anything but hierarchical star network topologies prompted a more automatic solution, as long as it is enabled on either end of a link, either type of cable can be used. For auto MDI-X to operate correctly, the rate on the interface. Auto MDI-X was developed by Hewlett-Packard engineers Daniel Joseph Dove and Bruce W. Melvin, a pseudo-random number generator decides whether or not a network port will attach its transmitter, or its receiver to each of the twisted pairs used to auto-negotiate the link. When two auto MDI-X ports are connected together, which is normal for modern products, the resolution time is typically <500 ms
8.
Modular connector
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A modular connector is an electrical connector that was originally designed for use in telephone wiring, but has since been used for many other purposes. Many applications that used a bulkier, more expensive connector have converted to modular connectors. Probably the most well known applications of modular connectors are for telephone jacks and for Ethernet jacks, Modular connectors were originally used in the Registration Interface system, mandated by the Federal Communications Commission in 1976 in which they became known as registered jacks. The registered jack specifications define the wiring patterns of the jacks, instead, these latter aspects are covered by ISO standard 8877, first used in ISDN systems. TIA/EIA-568 is a standard for data circuits wired on modular connectors, other systems exist for assigning signals to modular connectors, physical interchangeability of plugs and jacks does not ensure interoperation, nor protection from electrical damage to circuits. For example, modular cables and connectors have used to supply low-voltage AC or DC power. Modular connectors also go by the names modular phone jack/plug, RJ connector, the term modular connector arose from its original use in a novel system of cabling designed to make telephone equipment more modular. This includes the 4P4C handset connector, a very popular use of 8P8C today is Ethernet over twisted pair, and that may be the most well known context in which the name RJ45 is known, even though it has nothing to do with the RJ45 standard. Likewise, the 4P4C connector is sometimes called RJ9 or RJ22, Modular connectors were originally developed and patented by General Cable Corp in 1974. They replaced the hard-wired connections on most Western Electric telephones around 1976, at the same time, they began to replace screw terminals and larger 3 and 4 pin telephone jacks in buildings. Modular connectors have gender, plugs are considered to be male, while jacks or sockets are considered to be female, plugs are used to terminate loose cables and cords, while jacks are used for fixed locations on surfaces such as walls and panels, and on equipment. Other than telephone extension cables, cables with a plug on one end. Instead, cables are connected using an adapter, which consists of two female jacks wired back-to-back. Modular connectors are designed to latch together, a spring-loaded tab on the plug snaps into a jack so that the plug cannot be pulled out. To remove the plug, the latching tab must be depressed, the standard and most common way to install a jack in a wall or panel is with the tab side down. This usually makes it easier to operate the tab when removing the plug, because the person grabs the plug with thumb on top, the modular connector suffers from a design flaw or weakness however, as the fragile latching tab easily snags on other cables and breaks off. When this happens, the connector is still functional, but the crucial latching feature is lost, some higher quality cables have a flexible sleeve called a boot over the plug, or a special tab design, to prevent this. These cables are marketed as snagless
9.
Ethernet over twisted pair
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Ethernet over twisted pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network. Early Ethernet had used various grades of coaxial cable, but in 1984 and this led to the development of 10BASE-T and its successors 100BASE-TX and 1000BASE-T, supporting speeds of 10,100 and 1,000 Mbit/s respectively. All these three standards define both full-duplex and half-duplex communication, however, half-duplex operation for gigabit speed isnt supported by any existing hardware. All these standards use 8P8C connectors, and the cables from Cat3 to Cat8 have four pairs of wires, though 10BASE-T, the Institute of Electrical and Electronics Engineers standards association ratified several versions of the technology. The first two designs were StarLAN, standardized in 1986, at one megabit per second, and LattisNet, developed in January 1987. Both were developed before the 10BASE-T standard and used different signalling, in 1988 AT&T released StarLAN10, named for working at 10 Mbit/s. The StarLAN10 signalling was used as the basis of 10BASE-T, the centralized star topology was a more common approach to cabling than the bus in earlier standards and easier to manage. Using point-to-point links instead of a shared bus greatly simplified troubleshooting and was prone to failure. Exchanging cheap repeater hubs for more advanced switching hubs provided an upgrade path. Mixing different speeds in a single network became possible with the arrival of Fast Ethernet, depending on cable grades, subsequent upgrading to Gigabit Ethernet or faster may be as easy as replacing the network switches. The common names for the standards derive from aspects of the physical media, the leading number refers to the transmission speed in Mbit/s. BASE denotes that baseband transmission is used, the T designates twisted pair cable, where the pair of wires for each signal is twisted together to reduce radio frequency interference and crosstalk between pairs. Where there are standards for the same transmission speed, they are distinguished by a letter or digit following the T, such as TX, referring to the encoding method. Twisted-pair Ethernet standards are such that the majority of cables can be wired straight-through and it is conventional to wire cables for 10- or 100-Mbit/s Ethernet to either the T568A or T568B standards. The terms used in the explanations of the 568 standards, tip and ring, refer to older communication technologies, and equate to the positive and negative parts of the connections. A 10BASE-T or 100BASE-TX node such as a PC uses a connector wiring called medium dependent interfaces, transmitting on pin 1 and 2, an infrastructure node accordingly uses a connector wiring called MDI-X, transmitting on pin 3 and 6 and receiving on pin 1 and 2. These ports are connected using a cable, so each transmitter talks to the receiver on the other side. Nodes can have two types of ports, MDI or MDI-X, hubs and switches have regular ports
10.
Fast Ethernet
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In computer networking, Fast Ethernet is a collective term for a number of Ethernet standards that carry traffic at the nominal rate of 100 Mbit/s. Of the Fast Ethernet standards, 100BASE-TX is by far the most common, Fast Ethernet was introduced in 1995 as the IEEE802. 3u standard and remained the fastest version of Ethernet for three years before the introduction of Gigabit Ethernet. The acronym GE/FE is sometimes used for supporting both standards. Fast Ethernet is an extension of the 10-megabit Ethernet standard and it runs on UTP data or optical fiber cable in a star wired bus topology, similar to 10BASE-T where all cables are attached to a hub. Fast Ethernet devices are backward compatible with existing 10BASE-T systems. Fast Ethernet is sometimes referred to as 100BASE-X, where X is a placeholder for the FX, the standard specifies the use of CSMA/CD for media access control. A full-duplex mode is also specified and in all modern networks use Ethernet switches. The 100 in the type designation refers to the transmission speed of 100 Mbit/s. The letter following the dash refers to the medium that carries the signal. A Fast Ethernet adapter can be divided into a media access controller, which deals with the higher-level issues of medium availability. The MAC may be linked to the PHY by a four-bit 25 MHz synchronous parallel interface known as a media-independent interface, in rare cases the MII may be an external connection but is usually a connection between ICs in a network adapter or even within a single IC. The specs are based on the assumption that the interface between MAC and PHY will be a MII but they do not require it. Repeaters may use the MII to connect to multiple PHYs for their different interfaces, the MII fixes the theoretical maximum data bit rate for all versions of Fast Ethernet to 100 Mbit/s. 100BASE-T is any of several Fast Ethernet standards for twisted pair cables, including, 100BASE-TX, 100BASE-T4, the segment length for a 100BASE-T cable is limited to 100 metres. All are or were standards under IEEE802.3, almost all 100BASE-T installations are 100BASE-TX. In the early days of Fast Ethernet, much vendor advertising centered on claims by competing standards that said vendors standards will work better with existing cables than other standards. Thus most networks had to be rewired for 100 Megabit speed whether or not there had supposedly been CAT3 or CAT5 cable runs, 100BASE-TX is the predominant form of Fast Ethernet, and runs over two wire-pairs inside a category 5 or above cable. Like 10BASE-T, the pairs in a standard connection are terminated on pins 1,2,3 and 6
