WHAT IS NETWORKING ?

Here is some information to my little brothers who new to IT Profession.  Did any one know exactly what a networking is ? types of network ? how network help us ? 

              A network is nothing more than two or more computers connected to each

other so that they can exchange information, such as:

- e-mail messages or documents,

- Share resources, such as disk storage or printers.

The connection may be via electrical cables that carry electrical signals,

or fiber-optic cables by using impulses of light. Wireless networks let

computers communicate by using radio signals.

A network, in addition to special hardware, also requires special software

to enable communications. Network support is built into all major

operating systems, including all current versions of Windows, Macintosh

operating systems and Linux.

 - Client Computers

- Server Computers

- Network Interface Cards (NIC)

- Cables

- Hubs & Switches

- Wireless Networks

- Network Software

Client Computers

The computers that end-users use to access the resources of the network.

8They usually run a desktop version of Windows along with application

software such as Microsoft Office. Sometimes referred to as

WORKSTATIONS.

Server Computers

Computers that provide shared resources, such as disk storage and

printers, as well as network services, such as e-mail and Internet access.

Server computers typically run a specialized Network Operating System

(NOS) such as Windows 2000 Server, NetWare, or Linux along with special

software to provide network services.

For example, a server may run Microsoft Exchange to provide e-mail

services for the network, or it may run Apache Web Server so that the

computer can serve Web pages.

Network Interface Cards (NIC)

A card installed in a computer that enables the computer to communicate

over a network. Almost all NICs implement a networking standard called

ETHERNET. Every client and every server computer must have NIC (or

built-in network port) in order to be a part of the network.

Cables

Computers in a network are usually physically connected to each other

using cable. The most commonly used cable today is called Twisted Pair,

also known as 10BaseT. Another type of cable commonly used is Coaxial.

For high-speed network connections, fiber-optic cable is used.

Hubs & Switches

Each computer in a network is connected by cable to a device known as a

hub or switch. The hub or switch in turn, connects to the rest of the

network. Each hub or switch contains a certain number of ports, typically

8 or 16. Hubs and Switches can be connected to each other to build larger

networks.

Wireless Networks

In many networks, cables and hubs are making way for wireless network

connections, which enables computers to communicate via radio signals.

In a wireless network, radio transmitters and receivers take the place of

cables.

Advantage: Flexibility

Disadvantage: It is inherently less secure than a cabled network.

Network Software

What really makes a network work is software. Server computers typically

use special Network Operating System (NOS) in order to function

efficiently. Client computers need to have their network settings

configured properly in order to access the network.

Why Networking?

Networks are all about sharing. Specifically, networks are about sharing

three things: INFORMATION, RESOURCES & APPLICATIONS.

Sharing Information

Networks allow users to share information in several different ways. The

most common way of sharing information is to share individual files. In

addition to sharing files, networks allow users to communicate with each

other in various ways. Example: Messaging applications like Microsoft

Outlook. Users can also hold online meetings over the network. 8With

inexpensive Video Cameras and the right software, users can hold

videoconferences over the network.

Sharing Resources

Certain computer resources, such as printers or hard drives, can be set up

so that network users can share them. Providing users with access to a

shared hard drive is the most common method of sharing files on a

network.

 A computer whose main purpose is to host shared hard drives is called a

File Server. A network can be used to share an Internet connection.

Sharing Application

Networking businesses allow several users to work together on a single

business application. 8For example: An accounting department may have

accounting software that can be used from several computers at the same

time.

SERVERS & CLIENTS

Only two kinds of computers are on a network: Servers & Clients. The

network computer that contains the hard drive, printers and other

resources that are shared with other network computers is called a Server.

Any computer that’s not a server is called a Client.

Dedicated Servers & Peers

In some networks, a server computer is a server computer and nothing

else. This server computer is dedicated solely to the task of providing

shared resources, such as hard drives and printers, to be accessed by the

network client computers. Such a server is referred to as a dedicated

server because it can perform no other tasks besides network services. A

network that relies on dedicated servers is sometimes called a

client/server network.

Other networks take an alternative approach, enabling any computer on

the network to function as both a client and a server. Thus, any computer

can share its printers and hard drives with other computers on the

network. 8While a computer is working as a server, you can still use that

same computer for other functions such as word processing. This type of

network is called a peer-to-peer network because all the computers are

thought of as peers, or equals. Peer-to-peer networking features are built

into all current versions of Windows since Windows 95. Hence you don’t

have to buy any additional software to turn your computer into a server.

All you have to do is to enable the Windows Server features.

The network server features that are built into desktop versions of

Windows (such as Windows XP) aren’t very efficient because these

versions of Windows were not designed primarily to be network servers.

Hence you should use a full-fledged Network Operating System, such as

Windows 2000 Server.

Network Categorization

Based on the geographical size, its ownership, the distance it covers and

its physical architecture, networks can be categorized as:

- LAN: Local Area Network

- MAN: Metropolitan Area Network

- WAN: Wide Area Network

LAN

Computers are relatively close together, such as within the same office or

building. LAN can extend to several buildings on a campus – provided the

buildings are close to each other.

WAN

A network that spans a large geographical territory, such as an entire city,

region, or even an entire country. WANs are typically used to connect two

or more LANs that are relatively far apart.

MAN

A network that that’s smaller than a typical WAN but larger than a LAN.

Typically, a MAN connects two or more LANs within a same city but are far

enough apart that the networks can’t be connected using a simple cable

or wireless connection.

Network Topology

The term network topology refers to the shape of how the computers and

other network components are connected to

each other. Several different types of network

topologies:

- Bus Topology

- Star Topology

- Ring Topology

- Mesh Topology

Two Important Terms

NODE: is a device that is connected to the network.

PACKET: is a message that is sent over the network from one node to

another node.

Bus Topology

In this, the nodes are strung

together in a line. Commonly used

for LANs. Every node on the

network can see every packet that

is sent on the cable. If the cable in

a bus network breaks, the network is effectively divided into two

networks.

Star Topology

Each network node is connected to a

central device called a hub or a

switch. Also commonly used for LANs.

If a cable in a star network breaks,

only the node connected to that

cable is isolated from the network.

The other nodes can continue to

operate, unless, the node that is

isolated happens to be the File

Server.

Hub & Switch

A hub doesn’t know anything about the computers that are connected to

each of its ports. A switch knows which computer is connected to each of

its ports. Strictly speaking, only networks that use switches have a true

star topology. If the network uses a hub, the network topology has the

physical appearance of a star, but is actually a bus.

Ring Topology

Packets are sent around the circle from

computer to computer. Each computer looks

at each packet to decide whether the packet

was intended for it. If not, the packet is

passed on to the next computer in the ring.

Years ago, ring topologies were common in LANs, as two popular

networking technologies used rings: ARCNET and Token Ring. ARCNET is

still used for certain applications such as factory automation. Token Ring

is a popular network technology for IBM mid-range computers.

Mesh Topology

Mesh Topology has multiple connections between each of the nodes on the

network. Advantage: If one cable breaks, the network can use an

alternative route to deliver its packets. Mesh networks are not very

practicable in LAN setting. Mesh networks are common for metropolitan

or wide area networks. These networks use devices called routers to route packets from network to network. Routers are usually arranged to provide multiple paths between any two nodes.

The Downside of Networking

After you hook your computer up to a network, it’s not a Personal

Computer anymore. You are now part of a network of Computers. 8Two

disadvantages of using a network: the loss of user independence and the

need for network management.

Network Administration

At least one person should be designated as the Network Manager (also

called Network Administrator). He is responsible for making sure that the

network doesn’t fall apart or get out of control.

Manager’s Job

- To make sure that plenty of space is available on the File

Server

- To back up the File Server regularly

- To allow new employees access the network

- To solve basic problems that the users can’t themselves

solve

- To call in an expert when something really bad happens

UNDERSTANDING PROTOCOLS & STANDARDS

Understanding Protocols

Protocols & Standards are what make networks work together. Protocols

make it possible for the various components of a network to communicate

with each other. Standards also make it possible for network components

manufactured by different companies to work together.

A protocol is a set of rules that enable effective communications to occur.

Computer networks depend upon many different types of protocols, which

are very rigidly defined, in order to work. Various protocols tend to be

used together in matched sets called protocol suites.

The two most popular protocol suites for networking are: TCP/IP

(Transmission Control Protocol/ Internet Protocol) and IPX/SPX (Internet

Packet Exchange/ Sequenced Packet Exchange). TCP/IP was originally

developed for UNIX networks and is the protocol for the Internet. IPX/SPX

was originally developed for NetWare networks and is still widely used for

Windows networks. A third important protocol is Ethernet, a low-level

protocol that’s used with both TCP/IP and IPX/SPX.

Understanding Standards

A Standard is an agreed-upon definition of a protocol. Standards are

industry-wide protocol definitions that are not tied to a particular

manufacturer. Many organizations are involved in setting standards for

networking.

- ANSI: American National Standards Institute

- IEEE: Institute of Electrical & Electronics Engineers

- ISO: International Organization for Standardization

- IETF: Internet Engineering Task Force

- W3C: World Wide Web Consortium

OSI Reference Model

Open Systems Interconnection Reference Model is a framework into which

the various networking standards can fit. Open Systems Interconnection

Reference Model is a standard of standards. The OSI Model breaks the

various aspects of a computer network into seven distinct layers.

Layers Functions

APPLICATION File Transfer, e-mail, Remote login etc.

PRESENTATION ASCII Text, Sound

SESSION Establish/ Manage Connection

TRANSPORT End-to-End Communication: TCP

NETWORK Routing, Addressing: IP

DTA LINK Two party communication: Ethernet

PHYSICAL How to transmit signal: Coding

Ethernet Protocol

The most popular set of protocols for the Physical and Data Link layers is

Ethernet. The Ethernet is defined by the IEEE standard known as 802.3.

The actual transmission speed of Ethernet is measured in Mbps.

Ethernet comes in three different speed versions:

- Standard Ethernet - 10-Mbps

- Fast Ethernet – 100-Mbps

- Gigabit Ethernet – 1-Gbps (or 1000-Mbps)

TCP/IP Protocol Suite

The TCP/IP, the protocol on which the Internet is built, is actually not a

single protocol but rather an entire suite of related protocols. The TCP/IP

suite is based on a four-layered model of networking that is similar to the

seven-layer OSI Model.

TCP/IP Layers & Functions

APPLICATION LAYER

TRANSPORT LAYER

INTERNETWORK LAYER

NETWORK ACCESS LAYER

IPX/SPX Protocol Suite

Novell originally developed the IPX/SPX suite in the 1980s for use with

their NetWare Servers. 8IPX/SPX also works with all Microsoft Operating

Systems, with OS/2, and even with Unix and Linux.

IPX stands for Internet Package Exchange. It’s a Network layer protocol

that’s analogous to IP. SPX stands for Sequenced Package Exchange. It’s a

Transport layer protocol that’s analogous to TCP. Unlike TCP/IP, IPX/SPX

is not a standard protocol established by a standards group, such as IEEE.

Instead, IPX/SPX is a proprietary standard developed and owned by Novell.

Both IPX and IPX/SPX are registered trademarks of Novell.

Other Protocols Worth Knowing About

NetBIOS: Network Basic Input Output System

NetBEUI: Network BIOS Extended User Interface

AppleTalk: Apple Computers have their own suite of network

protocols known as AppleTalk

SNA: Systems Network Architecture is an IBM networking architecture

used with Mainframe computers

UNDERSTANDING NETWORK HARDWARE

The building blocks of networks are network hardware devices such as

servers, adapter cards, cables, hubs, switches, routers, and so on.

Servers

Server computers are the lifeblood of any network. Servers provide the

shared resources that network users crave, such as file storage, databases,

e-mail, Web services, and so on. For a home network or a small office

network with only a few computers, you can get away with true peer-topeer

networking. That’s where each client computer shares its resources

such as file storage or printers, and a dedicated server computer is not

needed.

Some general things to keep in mind when picking a server computer for

your network:

- Scalability

- Reliability

- Availability

- Service and Support

Server Form Factors

The term Form Factor refers to the size, shape, and packaging of a

hardware device. Server computers typically come in one of the three

form factors:

- Tower Case

- Rack Mount

- Blade Servers

Network Interface Cards (NIC)

Every computer on a network, both clients and servers, requires a network

interface card (NIC) in order to access the network. A NIC is usually a

separate adapter card that slides into one of the motherboard expansion

slots. However, some motherboards have a built-in network interface, so a

separate card isn’t required. Most NICs made today work with both 10Mbps

and 100Mbps UTP networks (that is, 10BaseT and 100BaseT) and are called

10/100 Cards.

Network Cable

We can construct an Ethernet network by using one of two different types

of cables:

- Coaxial Cable

- Twisted Pair Cable (UTP/ 10BaseT)

Hubs & Switches

The biggest difference between using coaxial cable and twisted-pair cable

is that when you use twisted-pair cable, you must also use a separate

device called a hub. A switch is simply a more sophisticated type of hub.

Repeaters

A Repeater is a device that gives your network signals a boost so that the

signals can travel farther. You need a repeater when the total length of a

single span of network cable is larger than the maximum allowed for the

cable type:

Cable Maximum Length

10Base2 (Coaxial) 185 metres

10/100BaseT (Twisted Pair) 100 metres

1.3.6 Bridges

A bridge is a device that connects two networks so that they act as if they

are one network. Bridges are used to partition one large network into two

smaller networks for performance reasons.

Routers

A router is like a bridge, but with a key difference. Bridges are Data Link

layer devices. A router is a Network layer device. A router is itself a node

on the network, with its own MAC and IP addresses.

UNDERSTANDING NETWORK OPERATING SYSTEMS

All network operating systems, from the simplest (such as Windows XP

Home Edition) to the most complex (such as Windows Server 2003), must

provide certain core functions.

Some of the core NOS features are:

- Network Support

- File Sharing Services

- Multitasking

- Directory Services

- Security Services

Microsoft Server Operating System

Microsoft currently supports three versions of flagship Server Operating

System:

- Windows NT Server

- Windows 2000 Server

- Windows Server 2003

Windows NT4 Server

Windows NT was a 32-bit processing, a huge step up from the 16-bit

processing of earlier versions of Windows. Windows NT was the first

Microsoft Operating System that was reliable enough to work as a network

server on large networks. Version 4.0 was shipped in July 1996.

Windows 2000 Server

Windows 2000 Server is currently the most popular server Operating

System from Microsoft. ØWindows 2000 Server, built on the strengths of

Windows NT Server, is faster, easier to manage, more reliable, and easier

to use for large and small networks alike.

Windows 2000 Server comes in three versions:

- Windows 2000 Server

- Windows 2000 Advanced Server

- Windows 2000 Datacenter Server

Windows Server 2003

Microsoft had just released a new version of Windows Server called

Windows Server 2003. For several years prior to its release, this new

version was called Windows .NET Server. Windows Server 2003 was built

on Windows 2000 Server with added features.

Windows Server 2003 comes in Four versions:

- Windows Server 2003, Standard Edition

- Windows Server 2003, Web Edition

- Windows Server 2003, Enterprise Edition

- Windows Server 2003, Datacenter Edition

Novell NetWare

NetWare is one of the most popular network operating systems, especially

for large networks. NetWare has an excellent reputation for reliability.

NetWare released the first version of NetWare in 1983.

The NetWare Versions are:

- Novell NetWare Version 3.x

- Novell NetWare Version 4.x

- Novell NetWare Version 3.x

- Novell NetWare Version 6

- Novell NetWare Version 6.5 (Released in 2003)

Other Server Operating Systems

Two other Server choices are:

- Linux

- Apple Mac OS/X Server

Linux is a free Operating System that is based on UNIX, a powerful

network operating system often used on large networks. Today, Linux is a

full-featured version of UNIX and can be an excellent choice as a Server

Operating System.

For Macintosh Networks, Apple offers a special network server Operating

System known as Mac OS/X Server. Mac OS/X Server has all the features of

a server operating system: file and printer sharing, Internet features, email,

and so on.