BASICS OF NETWORKING, ITS TYPES,

BASICS OF NETWORKING

WHAT IS A NETWORK?

A network consists of two or more computers that are linked in order to share resources (such as printers and CD-ROMs), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.

Computer networking technologies are the glue that binds these elements together. The public Internet allows businesses around the world to share information with each other and their customers. The global computer network known as the World Wide Web provides services that let consumers buy books, clothes, and even cars online, or auction those same items off when no longer

wanted

Advantages of Installing a Network

Speed: Networks provide a very rapid method for sharing and transferring files. Without a network, copying them to floppy disks, then carrying or sending the disks from one computer to another share files. This method of transferring files (referred to as sneaker-net) is very time-consuming.

Cost: Networkable versions of many popular software programs are available at considerable

savings when compared to buying individually licensed copies. Besides monetary savings, sharing a program on a network allows for easier upgrading of the program. The changes have to be done only once, on the file server, instead of on all the individual workstations.

Security: Files and programs on a network can be designated as “copy inhibit,” so that you do not have to worry about illegal copying of programs. Also, passwords can be established for specific directories to restrict access to authorized users.

Centralized Software Management: One of the greatest benefits of installing a network at a school is the fact that all of the software can be loaded on one computer (the file server).This eliminates that need to spend time and energy installing updates and tracking files on independent computers throughout the building.

Resource Sharing: Sharing resources is another area in which a network exceeds stand-alone computers. Most schools cannot afford enough laser printers, fax machines, modems, scanners and CD-ROM players for each computer. However, if these or similar peripherals are added to a network, they can be shared by many users.

Any machine capable of communicating on the network is called a device or node.

TYPES OF NETWORK

The three basic types of networks on the basis of their Size .They are:-

• Local Area Network (LAN)

• Metropolitan Area Network (MAN)

• Wide Area Network (WAN)

LAN (Local Area Network)

A network which covers a single floor, or perhaps an entire building, is known as a Local Area Network (LAN).Some features of LAN are as follows :-

1. It is an essential part of everyday functioning in schools, business, government etc

2. It Saves time, resources and allows information to be held securely and centrally

3. Improves collaboration between colleagues

4. May be used for training – capable of carrying audio and video

5. Several devices connected via cable to a hub

6. Hubs are the most common device found on a LAN

7. Some organisations will have LANs on each floor of a building connected by a bridge or router

8. All devices on the LAN communicate via network interface cards (NICs)

Characteristics include:

1. Used in small geographical areas

2. Offer high-speed communications (>10Mbps)

3. Provide access to many devices

4. Use LAN-specific devices such as repeaters, hubs and network interface cards

MAN (Metropolitan Area Networks)

LANs connected using high speed links across a metropolitan area is known as a MAN. A Metropolitan Area Network (MAN) covers larger geographic areas, such as cities or school districts. By interconnecting smaller networks within a large geographic area, information is easily disseminated throughout the network. Local libraries and government agencies often use a MAN to connect to citizens and private industries. There are three important features which discriminate

MANs from LANs or WANs:

• The network size falls intermediate between LANs and WANs. A MAN typically covers an area of between 5 and 50 km diameter. Many MANs cover an area the size of a city, although in some cases MANs may be as small as a group of buildings or as large as the state of Karnataka

• A MAN (like a WAN) is not generally owned by a single organization. The MAN, its communications links and equipment are generally owned by either a consortium of users or by a single network provider who sells the service to the users. This level of service provided to each user must therefore be negotiated with the MAN operator, and some performance guarantees are normally specified.

• A MAN often acts as a high-speed network to allow sharing of regional resources (similar to a large LAN). It is also frequently used to provide a shared connection to other networks using a link to a WAN.MAN is Made up of LANs which are interconnected across a metropolitan area.

1. Have become increasingly popular, e.g. among local government

2. Allows sharing of resources, plus the provision of a large-scale private phone service

3. Expensive to implement, provides high speed service (compared to WANs)

4. Requires use of high-performance cable and equipment to implement them

5. Can span up to 75 miles

6. Gives access speeds in hundreds of megabits per second (or even gigabits speeds)

7. Uses a single connection point to connect LANs

8. Uses routers and switches

WAN (wide Area Network)

If the public switched telephone network is used to connect the networks this is known as a Wide Area Network, or WAN.

1. Interconnects two or more LANs or MANs

2. Uses ‘slow’ connections leased from a Tel co.

3. Spans cities, countries or even continents

4. Requires co-ordination and expensive equipment

5. Speeds may be 56Kbps to 2 Mbps (speeds of 45Mbps are also available)

6. ‘Slow’ is comparative – faster speeds are emerging for use in WANs

7. Covers large areas – may span the world

8. Compared to LANs – slow speed communication

9. Access to WANs is limited – a LAN will access a WAN through a single point (often a bottleneck)

10. Will use devices such as routers, modems and WAN switches

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ईथरनेट शब्दावली /Ethernet Terminology

ईथरनेट शब्दावली ईथरनेट नियमों के एक सरल सेट का अनुसरण करता है जो इसके मूल संचालन को नियंत्रित करता है। इन नियमों को बेहतर ढंग से समझने के लिए, ईथरनेट शब्दावली की मूल बातें समझना महत्वपूर्ण है। मध्यम (Medium) ईथरनेट डिवाइस एक सामान्य माध्यम से जुड़ते हैं जो एक रास्ता प्रदान करता है जिसके साथ इलेक्ट्रॉनिक सिग्नल यात्रा करेंगे। ऐतिहासिक रूप से, यह माध्यम समाक्षीय तांबा केबल रहा है, लेकिन आज यह अधिक सामान्यतः एक मुड़ जोड़ी या फाइबर ऑप्टिक केबलिंग है। खंड ( Segment ) हम ईथरनेट खंड के रूप में एकल साझा माध्यम का उल्लेख करते हैं। नोड डिवाइस जो उस सेगमेंट से जुड़ते हैं वे स्टेशन या नोड होते हैं। ढांचा नोड्स छोटे संदेशों में कहे जाते हैं, जिन्हें फ्रेम कहा जाता है, जो सूचनाओं के भिन्न आकार होते हैं। फ़्रेम ( Frame ) मानव भाषा में वाक्यों के अनुरूप हैं। अंग्रेजी में, हमारे वाक्य बनाने के नियम हैं: हम जानते हैं कि प्रत्येक वाक्य में एक विषय और एक विधेय होना चाहिए। ईथरनेट प्रोटोकॉल फ्रेम के निर्माण के लिए नियमों का एक सेट निर्दिष्ट करता है। फ़्रेम के लिए अधिकतम लंबाई, और फ़्रे

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