Introduction

  • A typical network is consists of a larger number of the communication devices.
  • To build a typical LAN, we need to have computers, hubs, switches, network adapters, NICs, repeaters, amplifiers, UTP/STP cables, bridges, routers, gateways, internal/external modems, different types of connectors, cable testers, clipping tools etc. 

Definition

Features

Examples

  • Some popular example of networking devices are NIC adapters, routers, hubs, switches, modems, gateway and other related devices

NIC(Network Interface Card) Adapter Card/Network Card/Network Interface Controller

  • NIC is the simplest intra-networking device that is used in the data communication.
  • NIC adapter card is attached with the every computer that takes part in data communication.
  • A NIC is a piece of computer hardware (recently inbuilt with motherboard or early controllers are attached in motherboard expansion cards/ slots that plugged into a computer bus) to allow computers to communicate over a computer network.
  • It allows users to connect to each other, either by using cables or wirelessly.
  • The network controller implements the electronic circuitry required to communicate using a specific physical layer and data link layer standard such as Ethernet, Wi-Fi, or Token Ring.
  • NIC provides a base for a full network protocol stack, allowing communication among small groups of computers on the same LAN and large-scale network communications through routable protocols, such as IP.
  • The NIC follows one or more of four techniques to transfer data :-
    • Polling – In this method, the CPU examines the status of the peripheral under program control.
    • Programmed I/O – In this method, the microprocessor alerts the designated peripheral by applying its address to the system’s address bus.
    • Interrupt-Driven I/O – In this method, the peripheral alerts the microprocessor that it is ready to transfer data.
    • Direct Memory Access – In this method, an intelligent peripheral assumes control of the system bus to access memory directly. This removes load from the CPU but
      requires a separate processor on the card.

Repeater

    • A repeater is an electronic device that receives a signal and re-transmits it at a higher power, so that the signal can cover longer distances without degradation.
    • It works with the actual physical signal, and do not attempt to interpret the data being transmitted,
    • They operate on the Physical layer, the first layer of the OSI model.
    • In telecommunication sector, It is an analog device that amplifies an input signal regardless of its nature (analog or digital).
    • Typically, it is a digital device that amplifies, reshapes, retimes, or performs a combination of any of these functions on a digital input signal for retransmission.

Amplifier

Hub/Concentrator

    • A hub is a hardware device that contains multiple ports which is used to connect multiple devices in a star topology.
    • When a packet arrives at one port in hub, it is copied to all the ports of the hub. But when the packets are copied, the destination address in the frame does not change to a broadcast address. It does this in a rudimentary way; it simply copies the data to all of the Nodes connected to the hub (broadcast).
    • Advantages :
      • Improves the performance of especially bursty/heavy traffic and  also of large files.
      • Enables optimum performance of PCI computers.
      • Use of Fast Ethernet hubs require no hardware or software settings rather just plug them in. Thus, hub offers ease of use. 
    • Disadvantages :
      • Not suitable for variable traffic because hub has fixed bandwidth and as network traffic grows, performance suffers.
      • Does not reduce collisions.
      • Requires Category 5 UTP cabling for each 100BaseTX connection.

Switch

Modem (Modulator/Demodulator) 

    • Modem is a device that converts digital and analog signals, i.e. at the source, modems convert digital signals to a form suitable for transmission over analog communication facilities (public telephone lines) i.e. into analog signal. At the destination, modems again convert the analog signal back to a digital format.

Bridge

    • This intra networking device works at the data link layer.
    • Bridges are store and forward devices to provide error detection.
    • They capture an entire frame before deciding whether to filter or forward the frame, which provides a high level of error detection because a frame’s CRC checksum can be calculated by the bridge.
    • Bridges are highly susceptible to broadcast storms. A broadcast storm occurs when several broadcasts are transmitted at the same time. It can take up huge bandwidth.
    • Advantages:
      •  Reliability
      • Manageability
      • Scalability
    • Disadvantages:
      • A bridge cannot filter out broadcast traffic.
      • It introduces 20 to 30 % latency.
      • Only 2 networks can be linked with a bridge at a time.

Router

Gateway

  • In a communications network, gateway is a network node equipped for interfacing with another network that uses different protocols.
  • A gateway may contain devices such as protocol translators, impedance matching devices, rate converters, fault isolators, or signal translators as necessary to provide system interoperability.
  • A protocol translation/mapping gateway interconnects networks with different network protocol technologies by performing the required protocol conversions.
  • A gateway is a network point that acts as an entrance to another network.
  • On the Internet, gateway is a node or stopping point node or a host (end-point) node. Both the computers of Internet users and the computers that serve pages to users are host nodes, while the nodes that connect the networks in between are gateways.
  • In the enterprise network, a computer server acting as a gateway node is often simultaneously acting as a proxy server and a firewall server.
  • A gateway is often associated with both a router, which knows where to direct a given packet of data that arrives at the gateway, and a switch, which furnishes the actual path in and out of the gateway for a given packet.

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