Sunday, February 10, 2008

Network Devices and Components Overview

Network components and devices are the physical entities connected to a network. There are many types of network devices and increasing daily. The basic network devices are: Computers either a PC or a Server, Hubs, Switches, Bridges, Routers, Gateways, Network interface cards (NICs), Wireless access points (WAPs), Printers and Modems. The following is a overview of the main network components and devices:
Individual Computers: The personal computer is typically a desktop computer, a workstation or a notebook for individual users. The individual computers are the most common type of microcomputer and is found in the majority of organizations.
Server: A computer on a network or other network device that stores all necessary information and is dedicated to provide a particular service. For example, a database server would store all data and software related to a certain database and allows other network devices to access and process database queries. A file server is a computer and storage device dedicated to storing files for any user on the network to store files on the server. A print server is a device that manages one or more printers, and a network server is a computer that manages network traffic.
Network Interface Card: Network Interface Cards (NIC) are adaptors attached with a computer or other network device to provide the connection between the computer with the network. Each NIC is design for a specific type of network such as Ethernet, Token Ring, FDDI or wireless LAN. The NIC operates using the physical layer (layer 1) and data link layer (layer 2) specifications. NIC basically defines the physical connection methods with the cable and the framing methods used to transmit bit streams over the network. It also defines the control signals that provide the timing of data transfers across network.
Hubs: Hubs are the simplest network devices. Computers connect to a hub via a length of twisted-pair cabling. On a hub, data is forwarded to all ports, regardless of whether the data is intended for the system connected to the port. In addition to ports for connecting computers, even a very inexpensive hub generally has a port designated as an uplink port that enables the hub to be connected to another hub to create larger networks.
Switches:Switch is a layer 2 and multi-port device. Switch provides similar functions as a hub or a bridge but has more advanced features that can temporarily connect any two ports together. It contains a switch matrix or switch fabric that can rapidly connect and disconnect ports. Unlike Hub, a switch only forward frame from one port to the other port where the destination node is connected without broadcast to all other ports.
Routers: Routers route data around the network from data senders to receivers. A router is able to determine the destination address for the data and determines the best way for the data to continue its journey. Unlike bridges and switches, which use the hardware-configured MAC address to determine the destination of the data, routers use the logic network address such as IP address to make decisions.
Gateway: The term gateway is applied to any device, system, or software application that can perform the function of translating data from one format to another. Gateway will not change the data itself. For example, a router that can route data from an IPX network to an IP network is, technically, a gateway. The same can be said of a translational switch that converts from an Ethernet network to a Token Ring network and back again.
Modems: Modems are access devices that translate digital signals from a computer into analog signals that can travel across conventional phone lines. The modem modulates the signal at the sending end and demodulates at the receiving end. Modems are required for many access methods such as 56k data modern, ISDN, DSL etc. They can be as internal devices that plug into expansion slots in a system; external devices that plug into serial or USB ports; PCMCIA cards designed for use in laptops; and specialized devices designed for use in systems such as handheld computers. In addition, many laptops now come with integrated modems. For large-scale modem implementations, such as at an ISP, rack-mounted modems are also available.
Network Devices and Components Overview
Related Terms:Server, NIC, Gateway, Router, Hub, Switch, Modem
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