Found 1626 Articles for Computer Network

In computer networks, Gigabit Ethernet (GbE) is the family of Ethernet technologies that achieve theoretical data rates of 1 gigabit per second (1 Gbps). It was introduced in 1999 and was defined by the IEEE 802.3ab standard.Varieties of Gigabit EthernetThe popular varieties of fast Ethernet are 1000Base-SX, 1000Base-LX, 1000BASE-T and 1000Base-CX.1000BASE-CXDefined by IEEE 802.3z standardThe initial standard for Gigabit EthernetUses shielded twisted pair cables with DE-9 or 8P8C connectorMaximum segment length is 25 metresUses NRZ line encoding and 8B/6B block encoding1000BASE-SXDefined by IEEE 802.3z standardUses a pair of fibre optic cables of a shorter wavelength having 770 – 860 nm ... Read More

Throughput of a system refers to the rate of processing of a task thereby generating results. Ethernet is a set of technologies primarily used in LANs, whose primary data units are frames. The throughput of Ethernet is measured by the rate of successful delivery of frames over a communication channel.There are several methods for representing Ethernet throughput. The least ambiguous among them is calculation of channel efficiency. Channel efficiency, is the percentage of the net bit rate (in bits per second) of a channel that is actually communicated. Suppose that an Ethernet connection has a speed of 100 Mbps. But, ... Read More

Carrier Sense Multiple Access with Collision Detection (CSMA/CD) is a network protocol for carrier transmission that operates in the Medium Access Control (MAC) layer. It senses or listens whether the shared channel for transmission is busy or not, and defers transmissions until the channel is free.When more than one stations send their frames simultaneously, collision occurs. Back-off algorithm is a collision resolution mechanism which is commonly used to schedule retransmissions after collisions in Ethernet. The waiting time that a station waits before attempting retransmission of the frame is called as back off time.Algorithm of CSMA/CDStep 1) When a frame is ... Read More

100BASE-T4 is the early implementation of Fast Ethernet over twisted pair cables, carrying data traffic at 100 Mbps (Mega bits per second) in local area networks (LAN). It was launched as the IEEE 802.3u standard in 1995. Here, 100 is the maximum throughput, i.e. 100 Mbps, BASE denoted use of baseband transmission, and T4 denotes use of four twisted pair cables in Fast Ethernet.PropertiesThis has four pairs of unshielded twisted pair of Category 3. i.e. voice grade.Two of these pairs are bi-directional and the other two are unidirectional. The two unidirectional wires are reserved for receiving and sending data respectively. ... Read More

100BASE-FX is the technical name of Fast Ethernet over fiber optic cables. It is a version of Fast Ethernet carrying data traffic at 100 Mbps (Mega bits per second) in local area networks (LAN). It was launched as the IEEE 802.3u standard in 1995. Here, 100 is the maximum throughput, i.e. 100 Mbps, BASE denoted use of baseband transmission, and FX denotes use of optical fibers in Fast Ethernet.The 100BASE-FX Physical Medium Dependent (PMD) sublayer is defined by Fiber Distributed Data Interface (FDDI).PropertiesThis has two pairs of optical fibers. One pair transmits frames from hub to the device and the ... Read More

100BASE-TX is the technical name of Fast Ethernet over twisted pair cables. It is a predominant form of Fast Ethernet carrying data traffic at 100 Mbps (Mega bits per second) in local area networks (LAN). It was launched as the IEEE 802.3u standard in 1995. Here, 100 is the maximum throughput, i.e. 100 Mbps, BASE denoted use of baseband transmission, and TX denotes use of twisted pair cables in Fast Ethernet.PropertiesThis has either two pairs of unshielded twisted pairs (UTP) category 5 wires or two shielded twisted pairs (STP) type 1 wires.One of these pairs transmits frames from hub to ... Read More

In computer networks, Fast Ethernet is a variation of Ethernet standards that carry data traffic at 100 Mbps (Mega bits per second) in local area networks (LAN). It was launched as the IEEE 802.3u standard in 1995, and stayed the fastest network till the introduction of Gigabit Ethernet.Fast Ethernet is popularly named as 100-BASE-X. Here, 100 is the maximum throughput, i.e. 100 Mbps, BASE denoted use of baseband transmission, and X is the type of medium used, which is TX or FX.Varieties of Fast EthernetThe common varieties of fast Ethernet are 100-Base-TX, 100-BASE-FX and 100-Base-T4.100-Base-T4This has four pairs of UTP ... Read More

HubsA hub is a physical layer networking device which is used to connect multiple devices in a network. They are generally used to connect computers in a LAN.A hub has many ports in it. A computer which intends to be connected to the network is plugged in to one of these ports. When a data frame arrives at a port, it is broadcast to every other port, without considering whether it is destined for a particular destination or not.SwitchesA switch is a data link layer networking device which connects devices in a network and uses packet switching to send and ... Read More

ModulationModulation is the process of transforming a carrier signal so that it can carry the information of a message signal. It superimposes the contents of the message signal over a high-frequency carrier signal, which is then transmitted over communication channels.Modulation can be of two types −Analog ModulationDigital ModulationAnalog ModulationHere, the analog information signal is transformed to the analog carrier signal so that it can travel large distances without substantial loss.Analog modulation can be of three types −Amplitude ModulationFrequency ModulationPhase ModulationDigital ModulationDigital modulation is the process of converting a digital bit stream into an analog carrier wave for transmission via a ... Read More

Power line communications (PLC) allows data communications over conductors that are simultaneously used for transmission of electrical power.PLCs work by adding a modulated carrier signal, formed by superimposing data signal over low frequency power signal. Electrical signals transmit at 50 – 60 Hz, while the data signals transmit in the order of MHz.PLCs are also known as power line carrier, power line digital subscriber line (PDSL), or power line networking (PLN).Types of PLC:Narrowband PLC: They work at lower frequencies of 3-500KHz. Their data rates are low but have high range of several kilometres. They are used in the Smart Grid.Broadband ... Read More