NETWORKING CONCEPTS AND COMPONENTS

In summary, all networks must have the following:

A resource to share (resource)

A pathway to transfer data (transmission medium)

A set of rules governing how to communicate (protocols)

MODELS OF NETWORK COMPUTING

After you have the necessary prerequisites for network communi

cation, a structure must be put in place that organizes how commu

nication and sharing occurs. Three methods of organization, or

models, generally are recognized. The following are the three models

for network computing:

Centralized computing

Distributed computing

Collaborative or cooperative computing

Centralized Computing

Distributed Computing

Collaborative Computing

Also called cooperative computing, collaborative computing enables

computers in a distributed computing environment to share

processing power in addition to data, resources, and services.

In summary, collaborative computing involves the following:

Multiple computers cooperating to perform a task

Software designed to take advantage of the collaborative environment

NETWORK MODELS: COMPARING

CLIENT/SERVER AND PEER-TO-PEER

NETWORKING CONFIGURATIONS

Client/Server-Based Networking

A client/server network consists of a group of user-oriented PCs

(called clients) that issue requests to a server. The client PC is respon

sible for issuing requests for services to be rendered.

Peer-to-Peer Networking

A peer-to-peer network consists of a group of PCs that operate as

equals. Each PC is called a peer. The peers share resources (such as

files and printers) just like in a server-based network, although no

specialized or dedicated server machines exist. In short, each PC can

act as a client or a server.

LOCAL AND WIDE AREA NETWORKS

Local area networks (LANs)

Wide area networks (WANs)

Local Area Networks (LANs)

A local area network (LAN) is a group of computers and network

communication devices interconnected within a geographically lim

ited area, such as a building or a campus. LANs are characterized by

the following:

They transfer data at high speeds (higher bandwidth).

They exist in a limited geographical area.

Connectivity and resources, especially the transmission media,

usually are managed by the company running the LAN.

Wide Area Networks (WANs)

A wide area network (WAN) interconnects LANs. A WAN can be

located entirely within a state or a country, or it can be interconnect

ed around the world.

WANs are characterized by the following:

They exist in an unlimited geographical area.

They usually interconnect multiple LANs.

They often transfer data at lower speeds (lower bandwidth).

Connectivity and resources, especially the transmission media,

usually are managed by a third-party carrier such as a telephone or cable company

Data Migration

Data migration is a technology that automatically moves infrequently

used data from online storage to near-line or offline storage. The cri

teria for moving files can include when the files were last used, the

owner of the files, the files’ sizes, and a variety of other factors. An

efficient data-migration facility makes it easier to locate migrated

files. Figure 1.8 illustrates one approach to data migration. Data

migration is used when dealing with near-line storage systems

File Archiving

File archiving (also known as backup) is offline storage primarily

geared toward creating duplicate copies of online files. These backup

copies serve as insurance against minor or major system failures. A

redundant copy is made of important system, application, and data

files.

Generally, network administrators enable file archiving from a cen

tralized location. A single site, for example, can back up all the

servers on a network. Many current backup systems also offer the

capability to back up various client workstations, making it feasible

to archive all files on the network to a central facility. This makes

archiving possible whether the files are located on network servers or

on the clients. This archive is then stored in a safe location. A dupli

cate often is made and placed off the premises in case of disaster.