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

Data rate refers to the speed of data transfer through a channel. It is generally computed in bits per second (bps). Higher data rates are expressed as Kbps ("Kilo" bits per second, i.e.1000 bps), Mbps ("Mega" bits per second, i.e.1000 Kbps), Gbps ("Giga" bits per second, i.e. 1000 Mbps) and Tbps ("Tera" bits per second, i.e. 1000 Gbps).One of the main objectives of data communications is to increase the data rate. There are three factors that determine the data rate of a channel:Bandwidth of the channelNumber of levels of signals that are usedNoise present in the channelData rate can be ... Read More

Fourier analysis is a method of representing general functions by approximate sum of simple trigonometric functions. The method is named after mathematician Jean Baptiste Joseph Fourier who formulated and proved the Fourier series. Fourier analysis is used in electronics, communications and acoustics.The Fourier series decomposes a periodic function as a sum of sine and cosine components as expressed below:where, g(t) is the periodic functionT is the time periodf is the fundamental frequency expressed as 1/Tan is the sine amplitude of the nth harmonicbn is the cosine amplitude of the nth harmonicc is a constantThe values of an, bn and c ... Read More

Ethernet is a set of technologies and protocols that are used primarily in LANs. The performance of Ethernet is analysed by computing the efficiency of the channel under different load conditions.Let us assume an Ethernet network has k stations and each station transmits with a probability p during a contention slot. Let A be the probability that some station acquires the channel. A is calculated as −A = kp (1−p)kpThe value of A is maximized at p = 1/k. If there can be innumerable stations connected to the Ethernet network, i.e. k → ∞, the maximum value of A will ... Read More

The logical link control (LLC) is the upper sublayer of the data link layer of the open system interconnections (OSI) reference model for data transmission. It acts act an interface between the network layer and the medium access control (MAC) sublayer of the data link layer.The LLC sublayer is mainly used for its multiplexing property. It allows several network protocols to operate simultaneously within a multipoint network over the same network medium.LLC Layer in the OSI ModelThe Open System Interconnections (OSI) model is a 7 – layered networking framework that conceptualizes how communications should be done between heterogeneous systems. The ... Read More

Organizationally unique identifier (OUI) refers to a 24-bit number assigned to a manufacturer or a vendor of a network device or station. They are globally unique identifiers assigned by the Institute of Electrical and Electronics Engineers (IEEE) Registration Authority.OUI are typically used for uniquely identifying a particular device connected to the computer network through derived identifiers like the Medium Access Control (MAC) addresses. MAC addresses are of 6 octets ( 48-bits ). Among these, the first three octets of the addresses constitutes the OUI.A 3-octet OUI is generally represented in hexadecimal notation separated by dashes (for example, 1F – 9E ... Read More

Broadcasting in computer network is a group communication, where a sender sends data to receivers simultaneously. This is an all − to − all communication model where each sending device transmits data to all other devices in the network domain.The ways of operation of broadcasting may be −A high level operation in a program, like broadcasting in Message Passing Interface.A low level networking operation, like broadcasting on Ethernet.Broadcasting is shown in the following figure −Advantages of BroadcastingBroadcast helps to attain economies of scale when a common data stream needs to be delivered to all, by minimizing the communication and processing ... Read More