Network Components, Types and Connections

Module 2.

Client and Server Roles

Any computer connected to a network that participates in network communication is classified as a host. Hosts can send and receive, in modern networks, hosts can act as a client, server, or both.

Servers are hosts that have software installed to allow them to provide information, like email or web pages, to other hosts on the network. Each service provided requires separate software.

Clients are hosts that have software installed to allow them to request and view the info obtained from the server.

Peer-to-Peer

In small businesses and homes, hosts can operate as both client and server on the network, this is known as P2P (peer-to-peer). The simplest implementation of this is two computers connected directly to each other on the same network which can then exchange data with one another.

The advantages of P2P networking are:

• Easy setup

• Low cost because dedicated network devices are not required

• Used for simple tasks like file transfer and printer sharing

The disadvantages of P2P networking are:

• No centralized administration

• Not as secure

• Not scalable

• Performance can be slow

P2P applications allow devices to act as client & server in the same communication.

Network Infrastructure

This is the platform that supports a network, network infrastructure consists of: end devices, intermediate devices & network media.

End devices (or hosts) form the interface between users and the underlying network. Computers, printers, telephones, cameras and mobile devices are all examples of end devices. Hosts are either the source or destination of a message, to uniquely identify hosts, they are assigned addresses.

Internet Service Provider (ISP) Connectivity

An ISP is the link between a network and the internet. ISPs often offer auxiliary services to their clients like email accounts, network storage or website hosting. Each ISP connects to other ISPs to form links to connect users all over the world.

The interconnection of ISPs forms an information superhighway that connects the globe. This interconnection is provided by a huge web of fiber-optic cabling, expensive switches and routers to direct the flow of information.

Cable and Digital Subscriber Line (DSL)

Cable is typically offered by cable television service providers, the internet signal is carried on the coaxial cable which is also used to deliver television. A cable modem separates the internet signal from other signals carried on the cable as well as provides an Ethernet connection to a host computer.

DSL is a high bandwidth, always on, internet connection. This requires a special high-speed modem to separate the DSL signal from the telephone signal. DSL splits a telephone line into three channels. One channel is used for telephone calls, a second channel is used for downloads and a third channel is used for sending or uploading information. With DSL, the farther you are from the central office, the slower the connection will be.

Other connectivity options include:

• Cellular : uses a cell network to connect, performance limited by the phone and the tower to which it is connected. Advantageous for mobile users but downside is the carrier usually meters the bandwidth usage and it can incur charges.

• Satellite : good option for homes with no access to DSL or cable, satellite dishes require a clear line of site to the satellite, so this can struggle in heavily wooded areas. Equipment and installation costs can be hefty with a moderate monthly fee.

• Dial-up : inexpensive, uses a line and modem. Low bandwidth and should only be used when there is no other option.