Network Definitions Characteristics Components locations

What Is a Network?

The first assignment in understanding how to build a computer network is defining what a network is and understanding how it is used to help a business meet its objectives.

Network is a combination of computer hardware, cabling, network devices, and computer software used together to allow computers to communicate with each other.

Or

A network is basically all of the components (hardware and software) involved in connecting computers across small and large distances. Networks are used to provide easy access to information, thus increasing productivity for users.

Network hardware is mainly made by two basic components: the entities that want to share the information or resources, such as servers and workstations, and the medium that enables the entities to communicate, which is a cable or a wireless medium

Servers, Workstations, and Hosts

Host
The term host refers to any computer or device that is connected to a network and sends or receives information on that network. A host can be a server, a workstation, a printer with its own network card, or a device such as a router.
The server
is a special computer that contains more disk space and memory than are found on client workstations. The server has special software installed that allows it to function as a server.
Workstation
The workstation also is known as a client, which is just a basic computer running a client operating system such as Windows XP or Linux. A typical network involves having users sit at workstations, running such applications as word processors or spreadsheet programs.

Network Characteristics

The following characteristics should be considered in network design and ongoing maintenance:

• Availability.
  Availability is typically measured in a percentage based on the number of minutes that exist in a year. Therefore, up-time would be the number of minutes the network is available divided by the number of minutes in a year.
• Cost
  includes the cost of the network components, their installation, and their ongoing maintenance.
• Reliability
  defines the reliability of the network components and the connectivity between them. Mean time between failures (MTBF) is commonly used to measure reliability.
• Security
  includes the protection of the network components and the data they contain and/or the data transmitted between them.
• Speed
  includes how fast data is transmitted between network end points (the data rate).
• Scalability
  defines how well the network can adapt to new growth, including new users, applications, and network components.
• Topology
  describes the physical cabling layout and the logical way data moves between components.

Many different types and locations of networks exist. You might use a network in your home or home office to communicate via the Internet, to locate information, to place orders for merchandise, and to send messages to friends. You might have work in a small office that is set up with a network that connects other computers and printers in the office. You might work in a large enterprise in which many computers, printers, storage devices, and servers communicate and store information from many departments over large geographic areas.
Networks carry data in many types of environments, including homes, small businesses, and large enterprises. In a large enterprise, a number of locations might need to Communicate with each other, and you can describe those locations as follows:

 Corporate office:

A Corporate or main office is a site where everyone is connected via a network and where the bulk of corporate information is located. A Corporate office can have hundreds or even thousands of people who depend on network access to do their jobs. A main office might use several connected networks, which can span many floors in an office building or cover a campus that contains several buildings.

Remote locations:

A variety of remote access locations use networks to connect to the main office or to each other.

Branch offices:

In branch offices, smaller groups of people work and communicate with each other via a network. Although some corporate information might be stored at a branch office, it is more likely that branch offices have local network resources, such as printers, but must access information directly from the main office.

Home offices:

When individuals work from home, the location is called a home office. Home office workers often require on-demand connections to the main or branch offices to access information or to use network resources such as file servers.

Mobile users:

Mobile users connect to the main office network while at the main office, at the branch office, or traveling. The network access needs of mobile users are based on where the mobile users are located.

Network Components

All of these networks share many common components. As we describe in definition that network is basically sharing of information via network components. So network component play a major role in designing and maintaining network. Some most essential network components listed here.

Network Components
Applications	network-aware	network unaware
Protocols	open standard	proprietary
Computer	Windows, Macintosh OS, UNIX, Linux
Networking Devices	hubs, bridges, switches, routers, firewalls, wireless access points, modems
Media types	copper,coaxial,utp, fiber cabling

Types of Networks

Organizations of different structures, sizes, and budgets need different types of networks. Networks can be divided into one of two categories:

• peer-to-peer
• server-based networks

Peer-to-Peer Network

A peer-to-peer network has no dedicated servers; instead, a number of workstations are connected together for the purpose of sharing information or devices. Peer-to-peer networks are designed to satisfy the networking needs of home networks or of small companies that do not want to spend a lot of money on a dedicated server but still want to have the capability to share information or devices like in school, college, cyber cafe.

Server-Based Networks

In server-based network data files that will be used by all of the users are stored on the one server. With a server-based network, the network server stores a list of users who may use network resources and usually holds the resources as well.

This will help by giving you a central point to set up permissions on the data files, and it will give you a central point from which to back up all of the data in case data loss should occur.

Network Communications

• Computer networks use signals to transmit data, and protocols are the languages computers use to communicate.
• Protocols provide a variety of communications services to the computers on the network.
• Local area networks connect computers using a shared, half-duplex, baseband medium, and wide area networks link distant networks.
• Enterprise networks often consist of clients and servers on horizontal segments connected by a common backbone, while peer-to-peer networks consist of a small number of computers on a single LAN.