What is Networking? Networking involves connecting computers and other electronic devices for the purpose of sharing information and resources and for communication. An elementary network consists of two computers connected by some kind of transmission medium. Network enables users to exchange information and route data between them as workflow demands.

Types of Networks

Local Area Network (LAN): small network, limited to a single collection of machines and one or more cables and other peripheral equipment.

Internetwork: networked collection of LANs tied together by devices such as routers.

The Internet is the best example

Wide Area Network (WAN): internetwork that spans distances measured in miles and links two or more separate LANs.

Metropolitan Area Network (MAN): uses WAN technologies to interconnect LANs in a specific geographic region, such as a county or a city.

To communicate successfully, computers must share access to a common network medium such as twisted-pair, coaxial and fiber-optic cable, and wireless. The medium job is to carry the signals one computer sends to one or more other computers. Computers must attach to the network medium by using some kind of physical interface or network interface card (NIC) or network adapter.

Networks require a Network protocol: common set of rules that allows two computers on a network to communicate with one another. Examples includes TCP/IP, NetBEUI and IPX/SPX.

Computers need network software to issue the requests and responses that let them take the roles of clients and servers. This software is called a Network operating system (NOS). The NOS determines what services that computer can offer or request as well as the access to network services and network resources a computer makes available to clients.

Sharing resources and communication requires two components: a server component that provides access to the resource and a client component that requests access to the resource. The NOSs must be outfitted with the types of services your client operating systems require, whether they are Web servers, e-mail servers, file and print servers, and so on.

Networks fall into two major types: peer-to-peer and client/server (also called server-based). In a peer-to-peer network, every user must also act as a network administrator, controlling access to the resources on their machines. Computers can be affiliated into loose federations called workgroups, but no network-wide security can be enforced. As the number of users and resources grows, these networks can become unworkable.

Server-Based Networking has centralized user accounts, security, and access controls simplify network administration. A single password delivers access to network-wide resources as specified in access controls. Server-based networking makes the most sense for networks with 10 or more users or any networks where resources are heavily used.

Wireless personal area network (WPAN): short-range networking technology designed to connect personal devices to exchange information. Cell phones, pagers, PDAs, GPS devices, MP3 players, and even watches can belong to a WPAN.

The server is at the heart of any network that’s too large for a peer-to-peer configuration. Most large networks with more than a few dozen workstations rely on several network servers. In Windows Server 2000/2003 and Linux environments, these server types typically include application servers, communication servers, domain controllers/directory servers, fax servers, file and print servers, mail servers, and Web servers.

Application servers supply the server side of client/server applications, and often the data that goes along with them, to network clients.

Communication servers provide a mechanism for users outside a network to access that network’s resources, and sometimes permit users on a network to access resources outside network’s local scope.

Domain Controllers/Directory Servers make it possible to locate, store, and secure information about a network and its resources. A user belonging to a domain can access all resources and information that he or she has permission to use simply by logging on to the domain. Server that handles this logon service and manages the collection of computers, users, and so on in a domain is a domain controller or directory server.

Fax servers manage fax traffic for a network and receive incoming faxes via telephone, distribute them to recipients over the network, and collect outgoing faxes across the network before sending them via telephone.

File and print servers provide basic network file storage, retrieval services, and access to networked printers.

Mail servers handle e-mail messages for users.

Web-Based Networks are an integral and seamless part of the computing experience. Technologies such as the Microsoft .NET initiative and Web-enabled devices, such as cell phones and PDAs, promise to integrate the Web even further into people’s lives.

The Microsoft .NET computing model uses the Web to deliver applications and to enable applications on different devices running different operating environments to communicate and share data.

Selecting the Right Type of Network is critical. You have a number of choices to make when deciding how to design and implement a network. Will a single LAN do, or is an internetwork required? Is a MAN or WAN required? Will peer-to-peer networking suffice, or is a server-based network in order? Do some functions need to be server-based while others work well as a peer-to-peer network?

The decision to design a LAN or an internetwork is primarily based on how many total computers will participate on the network and whether there’s a need to tie groups of computers together with network devices such as routers. The distance the network will span also plays a part in the decision.

Choosing peer-to-peer networking exclusively is appropriate only when all the following hold:

A server-based network makes sense when one or more of the following conditions is true:

To implement a network, you must first decide how to best situate the components in a topology. A Topology refers to the physical layout of its computers, cables, and other resources, and also to how those components communicate with each other. The arrangement of cabling is the physical topology. The path that data travels between computers on a network is the logical topology. Topology has a significant effect on the network’s performance and growth, and equipment decisions.

Networks are based on three physical topologies. A bus consists of a series of computers connected along a single cable segment. Computers connected via a central concentration point (hub) are arranged in a star topology. Computers connected to form a loop create a ring.

Physical topologies describe cable arrangement. How the data travels along those cables might represent a different logical topology. The logical topologies that dominate LANs include bus, ring, and switching, all of which are usually implemented as a physical star.

Computers communicate by sending information across the media as a series of signals. In a typical (copper wire) physical bus, those signals are sent as electrical pulses that travel along the length of the cable in all directions. The signals continue to travel until they weaken enough so as not to be detectable or until they encounter a device that absorbs them. This traveling across the medium is called signal propagation.

Logical topologies describe the path that data travels from computer to computer. A physical bus topology is almost always implemented as a logical bus as well. Technology has moved past the physical bus, but a logical bus topology is still in use on some physical topologies, in particular a star.

When a computer has data to send, it addresses that data, breaks it into manageable chunks, and sends it across the network as electronic signals. All computers on a logical bus receive them. Only the destination accepts the data.

Data in a logical ring topology travels from one device, or node, on the network to the next device until the data reaches its destination. Token passing is one method for sending data around a ring. An advantage of the ring topology lies in its capability to share network resources fairly.

Switching is neither a bus nor a ring logically, but is always implemented as a physical star. A switch takes a signal coming from a device connected and builds a circuit on the fly to forward the signal to the intended destination computer. Switching is the dominant method used in almost every LAN design.

Wireless networking has a logical and physical topology. Wireless is an ad hoc topology where two computers can communicate directly with one another; sometimes called a peer-to-peer topology.

The first step in any network design is to evaluate the underlying requirements. First determine how the network will be used, which often decides the topology you use. Decide the types of devices for interconnecting computers and sites. Finally, the type and usage level of network resources dictates how many servers you need and where to place servers.

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