1.
Intel
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Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California that was founded by Gordon Moore and Robert Noyce. It is the worlds largest and highest valued semiconductor chip makers based on revenue, and is the inventor of the x86 series of microprocessors, Intel supplies processors for computer system manufacturers such as Apple, Lenovo, HP, and Dell. Intel Corporation was founded on July 18,1968, by semiconductor pioneers Robert Noyce and Gordon Moore, the companys name was conceived as portmanteau of the words integrated and electronics. The fact that intel is the term for intelligence information made the name appropriate. Intel was a developer of SRAM and DRAM memory chips. Although Intel created the worlds first commercial microprocessor chip in 1971, during the 1990s, Intel invested heavily in new microprocessor designs fostering the rapid growth of the computer industry. The Open Source Technology Center at Intel hosts PowerTOP and LatencyTOP, and supports other projects such as Wayland, Intel Array Building Blocks, and Threading Building Blocks. Client Computing Group – 55% of 2016 revenues – produces hardware components used in desktop, data Center Group – 29% of 2016 revenues – produces hardware components used in server, network, and storage platforms. Internet of Things Group – 5% of 2016 revenues – offers platforms designed for retail, transportation, industrial, buildings, non-Volatile Memory Solutions Group – 4% of 2016 revenues – manufactures NAND flash memory products primarily used in solid-state drives. Intel Security Group – 4% of 2016 revenues – produces software, particularly security, programmable Solutions Group – 3% of 2016 revenues – manufactures programmable semiconductors. In 2016, Dell accounted for 15% of Intels total revenues, Lenovo accounted for 13% of total revenues, in the 1980s, Intel was among the top ten sellers of semiconductors in the world. In 1991, Intel became the biggest chip maker by revenue and has held the position ever since, other top semiconductor companies include TSMC, Advanced Micro Devices, Samsung, Texas Instruments, Toshiba and STMicroelectronics. Competitors in PC chip sets include Advanced Micro Devices, VIA Technologies, Silicon Integrated Systems, however, the cross-licensing agreement is canceled in the event of an AMD bankruptcy or takeover. Some smaller competitors such as VIA Technologies produce low-power x86 processors for small factor computers, however, the advent of such mobile computing devices, in particular, smartphones, has in recent years led to a decline in PC sales. Since over 95% of the worlds smartphones currently use processors designed by ARM Holdings, ARM is also planning to make inroads into the PC and server market. Intel has been involved in disputes regarding violation of antitrust laws. Intel was founded in Mountain View, California in 1968 by Gordon E. Moore, a chemist, and Robert Noyce, arthur Rock helped them find investors, while Max Palevsky was on the board from an early stage. Moore and Noyce had left Fairchild Semiconductor to found Intel, Rock was not an employee, but he was an investor and was chairman of the board
2.
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
3.
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
4.
Optical fiber cable
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An optical fiber cable, also known as fiber optic cable, is a cable containing one or more optical fibers that are used to carry light. The optical fiber elements are typically coated with plastic layers. Different types of cable are used for different applications, for long distance telecommunication. Optical fiber consists of a core and a layer, selected for total internal reflection due to the difference in the refractive index between the two. In practical fibers, the cladding is coated with a layer of acrylate polymer or polyimide. This coating protects the fiber from damage but does not contribute to its optical waveguide properties, individual coated fibers then have a tough resin buffer layer and/or core tube extruded around them to form the cable core. Several layers of protective sheathing, depending on the application, are added to form the cable, rigid fiber assemblies sometimes put light-absorbing glass between the fibers, to prevent light that leaks out of one fiber from entering another. This reduces cross-talk between the fibers, or reduces flare in fiber bundle imaging applications, for indoor applications, the jacketed fiber is generally enclosed, with a bundle of flexible fibrous polymer strength members like aramid, in a lightweight plastic cover to form a simple cable. Each end of the cable may be terminated with an optical fiber connector to allow it to be easily connected and disconnected from transmitting and receiving equipment. For use in more environments, a much more robust cable construction is required. In loose-tube construction the fiber is laid helically into semi-rigid tubes and this protects the fiber from tension during laying and due to temperature changes. Loose-tube fiber may be dry block or gel-filled, dry block offers less protection to the fibers than gel-filled, but costs considerably less. Instead of a tube, the fiber may be embedded in a heavy polymer jacket. Tight buffer cables are offered for a variety of applications, Breakout cables normally contain a ripcord, two non-conductive dielectric strengthening members, an aramid yarn, and 3 mm buffer tubing with an additional layer of Kevlar surrounding each fiber. The ripcord is a cord of strong yarn that is situated under the jacket of the cable for jacket removal. Distribution cables have an overall Kevlar wrapping, a ripcord, and these fiber units are commonly bundled with additional steel strength members, again with a helical twist to allow for stretching. A critical concern in outdoor cabling is to protect the fiber from contamination by water and this is accomplished by use of solid barriers such as copper tubes, and water-repellent jelly or water-absorbing powder surrounding the fiber. Finally, the cable may be armored to protect it from environmental hazards, in September 2012, NTT Japan demonstrated a single fiber cable that was able to transfer 1 petabit per second over a distance of 50 kilometers
5.
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
6.
Conventional PCI
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Conventional PCI, often shortened to PCI, is a local computer bus for attaching hardware devices in a computer. PCI is the initialism for Peripheral Component Interconnect and is part of the PCI Local Bus standard, the PCI bus supports the functions found on a processor bus but in a standardized format that is independent of any particular processors native bus. Devices connected to the PCI bus appear to a bus master to be connected directly to its own bus and are assigned addresses in the address space. It is a bus, synchronous to a single bus clock. Attached devices can take either the form of an integrated circuit fitted onto the motherboard itself or a card that fits into a slot. The PCI Local Bus was first implemented in IBM PC compatibles and it has subsequently been adopted for other computer types. Typical PCI cards used in PCs include, network cards, sound cards, modems, extra ports such as USB or serial, TV tuner cards, PCI video cards replaced ISA and VESA cards until growing bandwidth requirements outgrew the capabilities of PCI. The preferred interface for video cards then became AGP, itself a superset of conventional PCI and these have one locating notch in the card. Version 2.0 of the PCI standard introduced 3.3 V slots, universal cards, which can operate on either voltage, have two notches. Version 2.1 of the PCI standard introduced optional 66 MHz operation, a server-oriented variant of conventional PCI, called PCI-X operated at frequencies up to 133 MHz for PCI-X1.0 and up to 533 MHz for PCI-X2.0. An internal connector for laptop cards, called Mini PCI, was introduced in version 2.2 of the PCI specification, the PCI bus was also adopted for an external laptop connector standard – the CardBus. The first PCI specification was developed by Intel, but subsequent development of the standard became the responsibility of the PCI Special Interest Group, Conventional PCIs heyday in the desktop computer market was approximately 1995–2005. PCI and PCI-X have become obsolete for most purposes, however, they are common on modern desktops for the purposes of backwards compatibility. Many kinds of devices available on PCI expansion cards are now commonly integrated onto motherboards or available in USB. Work on PCI began at Intels Architecture Development Lab c. 1990, a team of Intel engineers defined the architecture and developed a proof of concept chipset and platform partnering with teams in the companys desktop PC systems and core logic product organizations. PCI was immediately put to use in servers, replacing MCA, in mainstream PCs, PCI was slower to replace VESA Local Bus, and did not gain significant market penetration until late 1994 in second-generation Pentium PCs. By 1996, VLB was all but extinct, and manufacturers had adopted PCI even for 486 computers, EISA continued to be used alongside PCI through 2000. Apple Computer adopted PCI for professional Power Macintosh computers in mid-1995, the 64-bit version of plain PCI remained rare in practice though, although it was used for example by all G3 and G4 Power Macintosh computers
7.
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
8.
Hewlett-Packard
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The Hewlett-Packard Company or shortened to Hewlett-Packard was an American multinational information technology company headquartered in Palo Alto, California. The company was founded in a garage in Palo Alto by William Bill Redington Hewlett and David Dave Packard. HP was the worlds leading PC manufacturer from 2007 to Q22013 and it specialized in developing and manufacturing computing, data storage, and networking hardware, designing software and delivering services. HP also had services and consulting business around its products and partner products.4 billion in 2008, in November 2009, HP announced the acquisition of 3Com, with the deal closing on April 12,2010. On April 28,2010, HP announced the buyout of Palm, on September 2,2010, HP won its bidding war for 3PAR with a $33 a share offer, which Dell declined to match. On October 6,2014, Hewlett-Packard announced plans to split the PC and printers business from its enterprise products, the split closed on November 1,2015, and resulted in two publicly traded companies, HP Inc. and Hewlett Packard Enterprise. William Redington Hewlett and David Packard graduated with degrees in engineering from Stanford University in 1935. The company originated in a garage in nearby Palo Alto during a fellowship they had with a past professor, Terman was considered a mentor to them in forming Hewlett-Packard. In 1939, Packard and Hewlett established Hewlett-Packard in Packards garage with a capital investment of US$538. Hewlett and Packard tossed a coin to decide whether the company they founded would be called Hewlett-Packard or Packard-Hewlett, HP incorporated on August 18,1947, and went public on November 6,1957. Of the many projects they worked on, their very first financially successful product was an audio oscillator. This allowed them to sell the Model 200A for $54.40 when competitors were selling less stable oscillators for over $200, the Model 200 series of generators continued until at least 1972 as the 200AB, still tube-based but improved in design through the years. They worked on technology and artillery shell fuses during World War II. Hewlett-Packards HP Associates division, established around 1960, developed semiconductor devices primarily for internal use, instruments and calculators were some of the products using these devices. HP partnered in the 1960s with Sony and the Yokogawa Electric companies in Japan to develop several high-quality products, the products were not a huge success, as there were high costs in building HP-looking products in Japan. HP and Yokogawa formed a joint venture in 1963 to market HP products in Japan, HP bought Yokogawa Electrics share of Hewlett-Packard Japan in 1999. HP spun off a company, Dynac, to specialize in digital equipment. The name was picked so that the HP logo hp could be turned upside down to be a reverse image of the logo dy of the new company
9.
Twisted pair
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It was invented by Alexander Graham Bell. In balanced pair operation, the two wires carry equal and opposite signals, and the destination detects the difference between the two and this is known as differential mode transmission. Noise sources introduce signals into the wires by coupling of electric or magnetic fields, the noise thus produces a common-mode signal which is canceled at the receiver when the difference signal is taken. This problem is especially apparent in telecommunication cables where pairs in the same cable lie next to each other for many miles, one pair can induce crosstalk in another and it is additive along the length of the cable. Twisting the pairs counters this effect as on each half twist the wire nearest to the noise-source is exchanged, providing the interfering source remains uniform, or nearly so, over the distance of a single twist, the induced noise will remain common-mode. Differential signaling also reduces electromagnetic radiation from the cable, along with the associated attenuation allowing for greater distance between exchanges, the twist rate makes up part of the specification for a given type of cable. When nearby pairs have equal twist rates, the conductors of the different pairs may repeatedly lie next to each other. For this reason it is specified that, at least for cables containing small numbers of pairs. In contrast to shielded or foiled twisted pair, UTP cable is not surrounded by any shielding, UTP is the primary wire type for telephone usage and is very common for computer networking, especially as patch cables or temporary network connections due to the high flexibility of the cables. The earliest telephones used telegraph lines, or open-wire single-wire earth return circuits, in the 1880s electric trams were installed in many cities, which induced noise into these circuits. Lawsuits being unavailing, the telephone companies converted to balanced circuits, as electrical power distribution became more commonplace, this measure proved inadequate. Two wires, strung on either side of cross bars on utility poles, within a few years, the growing use of electricity again brought an increase of interference, so engineers devised a method called wire transposition, to cancel out the interference. In wire transposition, the wires exchange position once every several poles, in this way, the two wires would receive similar EMI from power lines. This represented an early implementation of twisting, with a twist rate of about four twists per kilometre, such open-wire balanced lines with periodic transpositions still survive today in some rural areas. Twisted-pair cabling was invented by Alexander Graham Bell in 1881, by 1900, the entire American telephone line network was either twisted pair or open wire with transposition to guard against interference. UTP cables are found in many Ethernet networks and telephone systems, for indoor telephone applications, UTP is often grouped into sets of 25 pairs according to a standard 25-pair color code originally developed by AT&T Corporation. A typical subset of these colors shows up in most UTP cables, for urban outdoor telephone cables containing hundreds or thousands of pairs, the cable is divided into small but identical bundles. Each bundle consists of twisted pairs that have different twist rates, the bundles are in turn twisted together to make up the cable
10.
Computer network
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A computer network or data network is a telecommunications network which allows nodes to share resources. In computer networks, networked computing devices exchange data with other using a data link. The connections between nodes are established using either cable media or wireless media, the best-known computer network is the Internet. Network computer devices that originate, route and terminate the data are called network nodes, nodes can include hosts such as personal computers, phones, servers as well as networking hardware. Two such devices can be said to be networked together when one device is able to exchange information with the other device, Computer networks differ in the transmission medium used to carry their signals, communications protocols to organize network traffic, the networks size, topology and organizational intent. In most cases, application-specific communications protocols are layered over other more general communications protocols and this formidable collection of information technology requires skilled network management to keep it all running reliably. The chronology of significant computer-network developments includes, In the late 1950s, in 1960, the commercial airline reservation system semi-automatic business research environment went online with two connected mainframes. Licklider developed a group he called the Intergalactic Computer Network. In 1964, researchers at Dartmouth College developed the Dartmouth Time Sharing System for distributed users of computer systems. The same year, at Massachusetts Institute of Technology, a group supported by General Electric and Bell Labs used a computer to route. Throughout the 1960s, Leonard Kleinrock, Paul Baran, and Donald Davies independently developed network systems that used packets to transfer information between computers over a network, in 1965, Thomas Marill and Lawrence G. Roberts created the first wide area network. This was an precursor to the ARPANET, of which Roberts became program manager. Also in 1965, Western Electric introduced the first widely used telephone switch that implemented true computer control, in 1972, commercial services using X.25 were deployed, and later used as an underlying infrastructure for expanding TCP/IP networks. In July 1976, Robert Metcalfe and David Boggs published their paper Ethernet, Distributed Packet Switching for Local Computer Networks, in 1979, Robert Metcalfe pursued making Ethernet an open standard. In 1976, John Murphy of Datapoint Corporation created ARCNET, a network first used to share storage devices. In 1995, the transmission speed capacity for Ethernet increased from 10 Mbit/s to 100 Mbit/s, by 1998, Ethernet supported transmission speeds of a Gigabit. Subsequently, higher speeds of up to 100 Gbit/s were added, the ability of Ethernet to scale easily is a contributing factor to its continued use. Providing access to information on shared storage devices is an important feature of many networks, a network allows sharing of files, data, and other types of information giving authorized users the ability to access information stored on other computers on the network
11.
Category 5 cable
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Category 5 cable, commonly referred to as Cat 5, is a twisted pair cable for carrying signals. This type of cable is used in structured cabling for computer networks such as Ethernet, the cable standard provides performance of up to 100 MHz and is suitable for 10BASE-T, 100BASE-TX, 1000BASE-T, and 2. 5GBASE-T. Cat 5 is also used to other signals such as telephony. This cable is connected using punch-down blocks and modular connectors. Most Category 5 cables are unshielded, relying on the balanced twisted pair design. Category 5 was superseded by the Category 5e specification, and later category 6 cable, the specification for category 5 cable was defined in ANSI/TIA/EIA-568-A, with clarification in TSB-95. These documents specify performance characteristics and test requirements for frequencies up to 100 MHz, cable types, connector types and cabling topologies are defined by TIA/EIA-568-B. Nearly always, 8P8C modular connectors are used for connecting category 5 cable, the cable is terminated in either the T568A scheme or the T568B scheme. The two schemes work equally well and may be mixed in an installation so long as the scheme is used on both ends of each cable. Each of the four pairs in a Cat 5 cable has differing precise number of twists per meter to minimize crosstalk between the pairs, although cable assemblies containing 4 pairs are common, category 5 is not limited to 4 pairs. Backbone applications involve using up to 100 pairs and this use of balanced lines helps preserve a high signal-to-noise ratio despite interference from both external sources and crosstalk from other pairs. The cable is available in both stranded and solid conductor forms, the stranded form is more flexible and withstands more bending without breaking. Permanent wiring is solid-core, while patch cables are stranded, the specific category of cable in use can be identified by the printing on the side of the cable. Most Category 5 cables can be bent at any radius exceeding approximately four times the diameter of the cable. The maximum length for a segment is 100 m per TIA/EIA 568-5-A. If longer runs are required, the use of hardware such as a repeater or switch is necessary. The specifications for 10BASE-T networking specify a 100-meter length between active devices and this allows for 90 meters of solid-core permanent wiring, two connectors and two stranded patch cables of 5 meters, one at each end. The category 5e specification improves upon the category 5 specification by revising and introducing new specifications to further mitigate the amount of crosstalk
12.
Ethernet crossover cable
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An Ethernet crossover cable is a type of Ethernet cable used to connect computing devices together directly. It is most often used to two devices of the same type, e. g. two computers or two switches to each other. By contrast, patch cables or straight through cables are used to connect devices of different types, the 10BASE-T and 100BASE-TX Ethernet standards use one wire pair for transmission in each direction. This requires that the pair of each device be connected to the receive pair of the device on the other end. When a terminal device is connected to a switch or hub, a standard straight through cable is used for this purpose where each pin of the connector on one end is connected to the corresponding pin on the other connector. One terminal may be connected directly to another without the use of a switch or hub, since 10BASE-T and 100BASE-TX use pairs 2 and 3, these two pairs must be swapped in the cable. A crossover cable may also be used to two hubs or two switches on their upstream ports. Such a cable will work for 10BASE-T or 100BASE-TX, the polarity of each pair is not swapped, but the pairs crossed as a unit, the two wires within each pair are not crossed. For this reason, there are no dedicated transmit and receive pairs, and consequently, crossover cables are never required for 1000BASE-T,2. 5GBASE-T, 5GBASE-T, 10GBASE-T, and 40GBASE-T communication. From 1000BASE-T onwards the physical medium attachment sublayer provides identification of each pair, however, when connecting an 100BASE-TX or 10BASE-T device to a faster port, a crossover may still be required in very rare situations. Since there are both transmitters and receivers present on a 1000BASE-T+ port on all pairs anyway, the Auto MDI-X function requires extremely little logic and is usually present. In practice, it does not matter if non-crossover Ethernet cables are wired as T568A or T568B, typical commercially available pre-wired cables can follow either format depending on the manufacturer. What this means is one manufacturers cables are wired one way and anothers the other way. In either case, T568A or T568B, a cable will have both ends wired identically according to the layout in either the Connection 1 column or the Connection 2 column. Certain equipment or installations, including those in which phone and/or power are mixed with data in the same cable, for most optical fiber variants of Ethernet, fibers are used in pairs with one fiber for each direction. Obviously, the one needs to be connected to the other receiver. For this, fiber patch cables with duplex connectors are normally configured as crossover as well as the on-premises wiring. Thus, a connection with two patch cables at each end and a section of fixed cable in the middle has got three crossovers in total, resulting in a working connection
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