Computer device part-2

 

FIREWALL

A firewall is a general term that refers to hardware

and software that restricts access to data and

information on a network. One of the uses of

firewall is to deny network access to outsiders. As

a public network, anyone with the proper

connection can access the Internet. A private

corporate intranet or extranet, by contrast,

restricts access to specific authorized users, usually

employees, suppliers, vendors and customers. To

prevent unauthorized access to data and

information, companies protect their intranet or

extranet with a firewall

                 

VOICE OVER INTERNET PROTOCOL

Voice over Internet Protocol, also called VoIP, IP Telephony, Internet telephony, Broadband telephony

Broadband Phone and Voice over Broadband is the routing of voice conversations over the Internet or

through any other IP-based network. Protocols which are used to carry voice signals over the IP

network are commonly referred to as Voice over IP or VoIP protocols. It is a rather new technology.

Telephone System: A VoIP system

allows people on a network to place phone

calls using the network instead of a traditional

telephone system. A company can replace its

entire telephone system with a VoIP system or

integrate VoIP into its existing telephone

system. Integrating Volp into an existing

telephone system allows people to use the

VoIP system to call other network users and a

traditional phone line to call people outside

the network

Hardware and Software: Dedicated hardware

and specialized software are needed by VolP system in

order to operate. A VolP system typically uses a device

similar to a hub to manage the phone calls made on

the network. VolP software is required to monitor and

maintain the efficiency and quality of voice

communications on the network.

WIRELESS NETwORKS

Devices, such as notebook computers and Personal

Digital Assistants (PDAs) can access information on a

network with a wireless network without being

physicaly connected to the network. A wireless

network eliminates the cables that connect devices

on a traditional network. Wireless networks allow

mobile devices to remain connected to the network

when they are moved from one area to another

Radio Signals:

Most wireless networks use radio signals to transmit

information between devices. These networks usually operate on radio

channels between 800 megahertz and 19 sgahertz. Information on a

wireless network can be transferred at speeds of up to 11 Mbps.

Radio Transceivers:

 A radio transceiver is used to exchange information on a network. Some

wireless devices have transceivers connected to the outside of the device, while other wireless devices

have built-in transceivers

RADIO TECHNOLOGY

There are three different ways to transfer information on a wireless network using radio signals.

GSMC: The Global System for Mobile Communications (GSMC) is the most popular transmission

technologY used on wireless standard for mobile phones in the world. This system transfers

information by compressing the information and then using a single radio channel from the zvailable

channels to transmit the data.

CDMA: Code Division Multiple Access (CDMA) is a popular transmission technology. This technology

transfers information between wireless devices by distributing the data over all the availabie radio

channels.

TDMA: Time Division Multiple Access (TDMA) divides one radio channel between multiple devices.

Each device takes turn using the channel. TDMA is used most often by businesses that offer digital

cellular communications

WIRELESS TECHNOLOGY

Although using wireless devices (Notebook, PDA, Smart phones, etc.) to access a network relies on

relatively new technology. there are several standards in place to ensure that wireless networks

function properly.

Bluetooth:

Bluetooth is an industrial specification for wireless personal area networks

(PANS). Bluetooth provides a way to connect and exchange information between devices such

as mobile phones, laptops, PCs, printers, digital cameras and video game consoles via a

secyre, globally unlicensed short-range radio frequency. Bluetooth lets these devices

communicate with each other when they are in range.

Ricochet:

Ricochet is a new network architecture designed for high-speed wireless networks

Ricochet network is created by placing wireless radio devices in various locations throughout am

area, such as on street corners in a city. Then wireless devices using Ricochet modems can accese

the radio devices to connect to the network. The Ricochet network architecture can transfe

intormation at speeds of up to 128 Kbps