Network Connectivity Devices

Computer networking devices are units that mediate data in A computer network and are also called network equipment. Units which are the last

receiver or generate data are called hosts or data terminal equipment.

Introduction

A network interface card is a computer hardware component designed to allow computers to communicate over a computer network.

It is both an OSI layer 1 (physical layer) and layer 2 (data link layer) device, as it provides physical access to a networking medium and provides a low-level addressing system through the use of MAC addresses.

It allows users to connect to each other either by using cables or wirelessly. Most motherboards today come equipped with a network interface card in

the form of a controller, with the hardware built into the board itself, eliminating the need for a standalone card.

NIC

Hubs are simple devices that are used in networks that use twisted-pair cabling to connect devices.

Hubs can be joined together to create larger networks. Hubs simply direct the data packets to all devices connected to the hub,

regardless of whether the data package is destined for the device. It means if one station sends it, all the others receive it, but only the

intended recipient listens to it. This makes them inefficient devices and can create a performance

bottleneck on busy networks.

HUBS

Like a hub, a switch connects multiple segments of a network together, but with one important difference.

Whereas a hub rebroadcasts anything it receives on one port to all the others, a switch makes a direct link between the transmitting device and receiving device.

Any party not involved in that communication will not receive the transmission.

The benefit of a switch over a hub is that the switch increases performance because it doesn’t suffer from the wasted bandwidth of the extra transmissions.

SWITCH 

A bridge is a network device that connects two similar network segments together.

The primary function of a bridge is to keep traffic separated on both sides of the bridge.

Traffic is allowed to pass through the bridge only if the transmission is intended for a station on the opposite side.

The main reason for putting a bridge in a network is to connect two segments together, or to divide a busy network into two segments.

BRIDGE

A router is a network device that connects multiple, often dissimilar, network segments into an internetwork.

The router, once connected, can make intelligent decisions about how best to get network data to its destination based on network performance data that it gathers from the network itself.

ROUTER

Any device that translates one data format to another is called a gateway. Some examples of gateways include a router that translates data from one

network protocol to another, a bridge that converts between two networking systems, and a software application that converts between two dissimilar formats.

The key point about a gateway is that only the data format is translated, not the data itself. In many cases, the gateway functionality is incorporated into another device.

GATEWAYS

A repeater is an electronic device that receives a signal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances without degradation.

Because repeaters work 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.

REPEATER

Modem (from modulator-demodulator) is a device that turns the digital 1s and 0s of a personal computer into sounds that can be transmitted over the telephone lines of Plain Old Telephone Systems (POTS), and once received on the other side, converts those sounds back into a form used by a USB, Ethernet, serial, or network connection.

Modems are generally classified by the amount of data they can send in a given time, normally measured in bits per second, or "bps".

MODEM

Media converters are simple networking devices that make it possible to connect two dissimilar media types such as twisted pair with fibre optic cabling.

Media converters support many different data communication protocols including Ethernet as well as multiple cabling types such as coaxial, twisted pair, multimode and single-mode fibre optics.

Media converters are useful in connecting multiple LANs to form one large "campus area network" that spans over a limited geographic area. As local networks are primarily copper-based, media converters can extend the reach of the LAN over single-mode fibre up to 130 kilometres with 1550 nm optics.

MEDIA CONVERTERS

Wireless access points (APs) are a transmitter and receiver (transceiver) device used to create a wireless LAN (WLAN).

APs are typically a separate network device with a built-in antenna, transmitter, and adapter.

APs use the wireless infrastructure network mode to provide a connection point between WLANs and a wired Ethernet LAN. APs also typically have several ports allowing a way to expand the network to support additional clients.

Depending on the size of the network, one or more APs might be required.

WIRLESS ACCESS POINTS

In addition to these network connectivity devices, there are several devices that, while maybe not directly connected to a network, participate in moving network data. Some of these devices include: Modems ISDN

Terminal Adapters CSU/DSUs

REST ALL

GRATITUDE

http://computernetworkingnotes.com/comptia-n-plus-study-guide/network-devices-hub-switch-router.html

http://www.quepublishing.com/articles/article.aspx?p=101728&seqNum=2

http://pluto.ksi.edu/~cyh/cis370/ebook/ch07b.htm

http://www.pearsonhighered.com/samplechapter/0789732548.pdf

REFERENCES