@import url("http://www.blogger.com/css/blog_controls.css"); @import url("http://www.blogger.com/dyn-css/authorization.css?blogID=8706105"); Hardik Shah - Trying to be with the Technology
Networks

Friday, April 29, 2005

Network Cable Standards DeMistified!!!

Moving more towards the networking stuff, here is something which is more essential - something which is always asked in our Orals during exams. Some standards of the Network Cables..

10Base2
An Institute of Electrical and Electronic Engineers (IEEE) standard for implementing 10 megabits per second (Mbps) Ethernet over thin coaxial cabling.

Overview
10Base2 is based on the 802.3 specifications of Project 802 developed by the IEEE. It was ratified as an IEEE standard in 1985 and quickly found its way into corporate
networks for small local area networks (LANs) connected to larger 10Base5 backbones.
10Base2 is sometimes referred to as thinnet or thin coax because it uses thin coaxial cabling for connecting stations to form a network (as compared to 10Base5, which uses a thicker form of cabling and hence is called thicknet). The designation 10Base2 is derived from the network’s speed (10 Mbps), the signal transmission method (baseband transmission), and the maximum
segment length (185 meters, rounded off to 200 with the zeros removed). Another popular nickname for this technology was Cheapernet because thinnet cabling was considerably less costly than thicknet cabling.

Implementation
10Base2 networks are wired together using a bus topology, in which individual stations (computers) are connected directly to one long cable. The maximum length of any particular segment of a 10Base2 network is 607 feet (185 meters). If distances longer than this are
required, two or more segments must be connected using repeaters. Altogether, a total of five segments can be connected using four repeaters, as long as only three of the segments have stations (devices) attached to them. This is referred to as the 5-4-3 rule. A 10Base2 segment should have no more than 30 stations wired to it. The minimum distance between these stations is 1.6 feet (0.5 meters). Stations are attached to the cable using BNC (British Naval Connector or Bayonet-Neill-Concelman) connectors, and the ends of the cabling have BNC cable connectors soldered or crimped to them. 10Base2 supports a maximum theoretical bandwidth of 10 Mbps, but in actuality the presence of collisions reduces this to more like 4 to 6 Mbps.

10Base2 networks are not deployed much anymore for two reasons. First, because their speed is limited to 10 Mbps, the networks perform poorly in today’s bandwidth-hungry, Internet-connected world. Second, 10Base2 networks have a single point of failure—the long, linear bus cable used to connect the stations. A single break or loose connection brings down the entire network, thus every cable segment and station connection must be checked to determine the problem. If you are wiring an office for a small LAN with low bandwidth requirements, use 10BaseT instead, which is easier to manage and troubleshoot. For moderate to high bandwidth requirements, try using Fast Ethernet instead. The two ends of a 10Base2 bus must be properly terminated. If they are not, signals will bounce and network communication will come to a halt.

10Base5
An Institute of Electrical and Electronic Engineers (IEEE) standard for implementing 10 megabits per second (Mbps) Ethernet over coaxial cabling.

Overview
10Base5 is based on the again on 802.3 specifications of Project 802 developed by the IEEE. It was developed as a standard in the early 1980s (I believe before 10Base2) and became hugely popular in corporate and campus networks. An earlier form of 10Mbps Ethernet developed by the DIX Consortium was superseded by 10Base5 when the IEEE 802.3 standard was created in 1983. 10Base5 is sometimes referred to as Thicknet because it uses thick coaxial cabling for connecting stations to form a network (compared to 10Base2, which uses a thinner form of cable and is hence called thinnet). Another name for 10Base5 is Standard Ethernet because it was the first type of Ethernet to be implemented (it is also sometimes referred to as Original Ethernet, for obvious reasons). The designation 10Base5 is derived from the network’s speed (10 Mbps), the signal transmission method (baseband transmission), and the maximum segment length (500 meters).

Implementation
10Base5 networks are wired together in a bus topology—that is, in a linear fashion using one long cable. The maximum length of any particular segment of a 10Base5 network is 1640 feet (500 meters). If distances longer than this are required, two or more segments must be connected using repeaters. Altogether, there can be a total of five segments connected using four
repeaters, as long as only three of the segments have stations (computers) attached to them. This is referred to as the 5-4-3 rule. A 10Base5 segment should have no more than 100 stations
wired to it. These stations are not connected directly to the cable as in 10Base2 networks.

Instead, a transceiver is attached to the cable, usually using a cable-piercing connector called a vampire tap. From the transceiver, a drop cable is attached, which then connects to the network interface card (NIC) in the computer. The minimum distance between transceivers attached to the cable is 8 feet (2.5 meters), and the maximum length for a drop cable is 164 feet (50 meters). Thicknet cable ends can have N-series connectors soldered or crimped on them for connecting segments together. 10Base5 was often used for backbones for large networks.
In a typical configuration, transceivers on the thicknet backbone would attach to repeaters, which would join smaller thinnet segments to the thicknet backbone. In this way a combination of 10Base5 and 10Base2 standards could support sufficient numbers of stations for the needs of a moderately large company. 10Base5 supports a maximum bandwidth of 10 Mbps, but in actual networks, the presence of collisions reduces this to more like 4 to 6 Mbps.

10Base5 networks are legacy networks that are no longer being deployed, although some companies might choose to maintain existing ones for cost reasons. The complexity and bandwidth limitations of 10Base5 networks render them largely obsolete. If you are wiring an office for a small local area network (LAN) with low bandwidth requirements, use 10BaseT instead. For moderate to high bandwidth requirements, try using Fast Ethernet. If you are implementing a backbone for today’s high-speed enterprise networks, Gigabit Ethernet (GbE) is now the preferred technology.

10BaseF
An Institute of Electrical and Electronic Engineers (IEEE) standard for implementing 10 megabits per second (Mbps) Ethernet over fiber-optic cabling.

Overview
10BaseF is based on the 802.3 specifications of Project 802 developed by the IEEE and differs from other forms of 10-Mbps Ethernet by using fiber-optic cabling instead of copper unshielded twisted-pair (UTP) cabling. The designation 10BaseF is derived from the network’s speed (10 Mbps), the signal transmission method (baseband transmission), and the physical media used (fiber-optic cabling). The 10BaseF standard actually consists of three separate standards describing different media specifications:

  • 10BaseFB: Defines how the synchronous data transmission occurs over the fiber-optic cabling. Using 10BaseFB segments, you can cascade or link synchronous fiber-optic hubs in configurations that are longer than traditional 10BaseT Ethernet networks and contain up to 1024 stations. This standard is more expensive and is not as widely implemented as 10BaseFL.
  • 10BaseFL: Defines the characteristics of the fiber-optic link between the nodes and the hub or concentrator. 10BaseFL replaces the older standard for fiber-optic link segments, Fiber-Optic Inter-Repeater Link (FOIRL) segments, which was developed in the 1980s. 10BaseFL is the most commonly implemented version of 10BaseF.
  • 10BaseFP: Defines the implementation of a star topology that does not use repeaters. 10BaseFP stands for Fiber Passive, and its segments can be only 500 meters (1640 feet) in length with a maximum of 33 stations connected. This standard is rarely used today.

Implementation
10BaseF is similar to 10BaseT in that each station is wired into a hub in a star topology to form the network. The maximum length of any segment of 10BaseF fiber-optic cabling is 6600 feet (2000 meters), compared to the 328 feet (100 meters) supported by 10BaseT, making 10BaseF suitable for long-haul interconnects. The recommended cabling type for 10BaseF networks is 62.5-micron diameter fiber-optic cabling. This cable can be terminated with either ST connectors or SMA connectors, depending on the vendor and the hub configuration. Two-strand multimode fiber-optic cabling is used, with one strand allotted for transmitting data and the other for receiving data.

10BaseF is preferable to 10BaseT in environments that are electrically noisy, such as in industrial areas, near elevator shafts, or around other motors or generators. Fiber-optic cabling is often used for running cables between buildings. Differences in ground potential between the ends of copper cabling can induce voltages that can damage networking equipment if the ends are not grounded properly. Fiber-optic cabling also supports faster speeds than copper UTP cabling and provides a more suitable upgrade option to Fast Ethernet and beyond. The maximum signal loss or attenuation on a given segment should be no more than 12.5 decibels. Using too many connectors in a segment of fiber-optic cabling can cause the attenuation to exceed this figure, which can lead to signal loss.

10BaseT
An Institute of Electrical and Electronic Engineers (IEEE) standard for implementing 10 megabits per second (Mbps) Ethernet over twisted-pair cabling.

Overview
10BaseT is based on the 802.3 specifications of Project 802 developed by the IEEE and is the most popular form of 10-Mbps Ethernet. 10BaseT is deployed over structured cabling systems consisting of unshielded twisted-pair (UTP) cabling used for connecting end stations to centralized hubs to form a network. (Shielded twisted-pair [STP] cabling can also be used, but it never is.) The designation 10BaseT comes from the network’s speed (10 Mbps), the signal transmission method (baseband transmission), and the physical medium used for transmission (twisted-pair cabling). 10BaseT became widely popular because of the earlier success of the Public Switched Telephone Network (PSTN), a hierarchical structured-wiring system to which 10BaseT bears many similarities. An advantage of 10BaseT over earlier 10 Mbps Ethernet systems such as 10Base5 and 10Base2 is that it is easier to manage because of the centralization of network traffic in hubs.

Implementation
In10BaseT networks, end stations such as workstations and servers are wired together in a star topology to a central hub. The UTP cabling used for wiring should be Category 3 (Cat3) cabling, Category 4 (Cat4) cabling, or Category 5 (Cat5) cabling, terminated with RJ-45 connectors. Patch panels can be used to organize wiring and provide termination points for cables running to
wall plates in work areas. Patch cables then connect each port on the patch panel to the hub. Usually most of the wiring is hidden in a wiring cabinet and arranged on a rack for easy access.
The maximum length of any particular segment of a 10BaseT network is 328 feet (100 meters). In practice this is not a limitation because a survey by AT&T indicated that about 99 percent of desktops in commercial buildings are located within 328 feet (100 meters) of a wiring closet. If distances longer than that are required, two or more segments may be connected using repeaters. The minimum length of any given segment is restricted to 8 feet (2.5 meters).
By using stackable hubs or by cascading regular hubs into a cascaded star topology, you can network large numbers of computers using 10BaseT cable. Although 10BaseT can support up to 1024 nodes, networks with no more than 200 or 300 nodes will yield the best performance
by keeping collision domains small. Hubs can be hierarchically arranged to a depth of up to three levels in order to accommodate much larger networks, but performance declines significantly as the number of stations exceeds several hundred.

Although 10BaseT theoretically supports a maximum bandwidth of 10 Mbps, in actual networks the presence of collisions reduces throughput to about 4 to 6 Mbps. The maximum length of a 10BaseT cable segment is not a result of the specifications for round-trip communications
on an Ethernet network but rather a limitation caused by the relatively low signal strength of 10BaseT systems. With enhanced Category 5 (Cat5e) cabling, you might be able to sustain network communications effectively with cable lengths up to about 490 feet (150 meters), although this is not normally recommended.

100BaseFX
An Institute of Electrical and Electronics Engineers (IEEE) standard for implementing 100 megabits per second (Mbps) Ethernet over fiber-optic cabling.

Overview
100BaseFX is based on the 802.3u standard, which is an extension of the 802.3 standard of Project 802 developed by the IEEE. It’s a type of Fast Ethernet that is often used for wiring campus backbones using fiber-optic cabling. The designation 100BaseFX is derived from the network’s speed (100 Mbps), the signal transmission method (baseband transmission), and the physical medium used for transmission (fiber-optic cabling).

Implementation
100BaseFX networks are wired together in a star topology using fiber-optic cabling and 100-Mbps fiber-optic hubs or Ethernet switches. 100BaseFX systems may be interconnected with 100BaseTX, 100BaseT4, and 10BaseT systems using auto negotiating hubs and switches with suitable ports. Two-strand fiber-optic cabling is required, and ST, SC, and MIC connectors are all supported. Signaling is at 125 megahertz (MHz), which when combined with the 80 percent efficiency of the 4B5B line coding mechanism used results in an overall transmission speed of 100 Mbps. The maximum length of any segment of fiber-optic cabling connecting a station (computer) to a hub in 100BaseFX is 1350 feet (412 meters), and not 1480 feet (450 meters) as some sources indicate. The grade of fiber-optic cabling used is usually two-strand multimode fiber-optic cabling, with one strand carrying transmitted data and the other strand receiving data. However, you can also use two-strand single-mode fiber-optic cabling. If multimode fiber-optic cabling is used, the variety used is typically a grade with a 62.5-micron core diameter.
Repeaters can be used to extend the length of cabling and for interfacing between 100BaseFX/TX and 100BaseT4 segments. The maximum allowable distances with repeaters are 2 kilometers using multimode fiber-optic cabling and 10 kilometers using singlemode
fiber-optic cabling. Only one or two repeaters can be used per collision domain, depending on
whether Class I or Class II repeaters are used.

100BaseFX and a related standard, 100BaseTX, are sometimes collectively referred to as 100BaseX. When using 100BaseFX with repeaters for backbone cabling runs, Ethernet switches cannot be more than 1350 feet (412 meters) apart when running in halfduplex mode and 6600 feet (2000 meters) apart when running in full-duplex mode.

100BaseT4
An Institute of Electrical and Electronics Engineers (IEEE) standard for implementing 100 megabits per second (Mbps) Ethernet over twisted-pair cabling.

Overview
100BaseT4 is based on 802.3u, which is an extension of the 802.3 specifications of Project 802 developed by the IEEE. 100BaseT4 is the most commonly used implementation of Fast Ethernet today. The designation 100BaseT4 is derived from the network’s speed (100 Mbps), the signal transmission method (baseband transmission), and the physical medium used for transmission (all four pairs of wires in standard twisted-pair cabling). 100BaseT4 is now considered legacy technology and has been largely superseded by 100BaseTX.

Implementation
100BaseT4 networks are wired together in a star topology using unshielded twisted-pair (UTP) cabling and 100-Mbps hubs or Ethernet switches. The UTP cabling involved may be Category 3 (Cat3), Category 4 (Cat4), or Category 5 (Cat5) cabling—with Cat5 cabling and enhanced Category 5 (Cat5e) cabling being the most commonly used solutions nowadays. 100BaseT4 uses all four pairs of wire in standard UTP cabling, for signaling with signaling rates of 25 megahertz
(MHz) and an 8B6T line coding mechanism. One pair is used exclusively for transmission and a second pair for reception. The other two pairs are bidirectional and can be used either to transmit or to receive data as required. In this way, three of the four wire pairs are used at any given time to provide half-duplex transmission or reception of signals. Sharing three pairs of wires for data transfer allows 100BaseT4 to make use of lower-grade Cat3 cabling already installed in many older buildings. The maximum length of any segment of cabling connecting
a station (computer) to a hub is 328 feet (100 meters). This ensures that round-trip signaling specifications are met, because violating these specifications can produce late collisions that disrupt network communications. The Electronic Industries Alliance/Telecommunications
Industry Association (EIA/TIA)– recommended length of cabling between the station and the wiring closet is only 295 feet (90 meters), allowing up to 32 feet (10 meters) more of cabling for patch cables used to connect patch panels to hubs or switches. The pinning of the RJ-45 connectors used for 100BaseT4 wiring is the same as for 10BaseT wiring.

Make sure all your cabling, connectors, and patch panels are fully Cat5-compliant. For example, ensure that when UTP cabling is connected to patch panels, wall plates, or connectors, the wires are not untwisted more than half an inch at the termination point. 100BaseT4 hubs and switches are typically available in an autosensing 10/100-Mbps variety for interoperability
with older 10BaseT networks and to facilitate an easy upgrade from 10BaseT to 100BaseT.

100BaseTX
An Institute of Electrical and Electronics Engineers (IEEE) standard for implementing 100 megabits per second (Mbps) Ethernet over twisted-pair cabling.

Overview
100BaseTX is based on 802.3u, which is an extension of the 802.3 specifications of Project 802 developed by the IEEE. The designation 100BaseTX is derived from the network’s speed (100 Mbps), the signal transmission method (baseband transmission), and the physical medium used for transmission (the same two pairs of wires in standard four-wire twisted-pair cabling that are
used for 10BaseT Ethernet).

Implementation
100BaseTX networks are wired together in a star topology using either unshielded twisted-pair (UTP) cabling or data-grade shielded twisted-pair (STP) cabling. If UTP cabling is used (which is the most common scenario), it must be Category 5 (Cat5) cabling or enhanced Category 5 (Cat5e) cabling. Stations are connected together using hubs or switches. Unlike 10BaseT hubs, which can be hierarchically connected up to three levels deep, 100BaseTX hubs can only be
connected two layers deep, which imposes additional distance limitations and may necessitate rewiring of existing cabling before upgrading from 10BaseT to 100BaseTX.

100BaseTX uses the two pairs of wires in twistedpair cabling that are used by 10BaseT networks, with one pair of wires used for transmission and the other used for reception. With the appropriate equipment, 100BaseTX is capable of supporting both the familiar half-duplex Ethernet used by 10BaseT and newer full-duplex Ethernet signaling technologies. 100BaseTX employs a signaling rate of 125 megahertz (MHz) for each pair of wires, which, because the 4B5B line coding algorithm used is only 80 percent efficient, translates into a data transmission speed of 100 Mbps. The maximum length of any segment of cabling connecting a station to a hub is 328 feet (100 meters). This ensures that round-trip signaling specifications are met, because violating these specifications can produce late collisions that disrupt network communications. The pinning of the RJ-45 connectors used for 100BaseTX wiring is the same as for 10BaseT wiring with wires 1 and 2 used for transmission and wires 3 and 6 used for reception. This enables 100BaseTX autosensing hubs and switches to operate in mixed 10/100 Mbps Ethernet networks.

The maximum distance between 100BaseTX hubs and bridges or switches is 738 feet (225 meters), further than the maximum hub-station distance of only 328 feet (100 meters).
100BaseTX and a related standard, 100BaseFX, are sometimes collectively referred to as 100BaseX. Although the maximum length of segments joining stations to hubs is 328 feet (100 meters), the Electronic Industries Alliance/Telecommunications Industry Alliance (EIA/TIA) recommends only 295 feet (90 meters) of cabling between the station (computer) and the wiring closet, allowing up to 32 feet (10 meters) more of cabling for patch cables used to connect patch panels to hubs or switches.

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