Lecture 01 networking

Information Technology III

Lecture 01 – Types of networks

What is a Network? A system of interconnected computers and computerized

peripherals such as printers in order to facilitates information sharing among them is called computer network

Computers may connect to each other by either wired or wireless media

Classification of Computer Networks Computer networks are on various factors

Geographical span Inter-connectivity Administration Architecture

Geographical Span Spanned across your table, among Bluetooth enabled devices,.

Ranging not more than few meters.

Spanned across a whole building, including intermediate devices to connect all floors.

Spanned across a whole city.

Spanned across multiple cities or provinces.

One network covering whole world.

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Personal Area Network (PAN) It is smallest network which is very personal to a user.

This may include Bluetooth enabled devices or infra-red enabled devices.

It has connectivity range up to 10 meters.

It may include wireless computer keyboard and mouse, Bluetooth enabled headphones, wireless printers and TV remotes.

Local Area Network (LAN) A computer network spanned inside a building and operated under single

administrative system is generally termed as Local Area Network

It covers an organization’ offices, schools, colleges or universities

It provides sharing the resources between end users such as Printers file servers Mail servers scanners and internet

Local Area Network (LAN)

It may contains local servers serving file storage and other locally shared applications.

It mostly operates on private IP addresses

It works under its own local domain and controlled centrally

Main technologies are Ethernet or Token-ring Ethernet is most widely technology with Star topology

LAN can be wired, wireless, or in both forms at once.

Virtual LAN (VLAN) Virtual LAN is a solution to divide a single Broadcast domain into

multiple Broadcast domains.

Host in one VLAN cannot speak to a host in another. By default, all hosts are placed into the same VLAN.

Metropolitan Area Network (MAN)

IT generally expands throughout a city such as cable TV network.

It can be in the form of Ethernet, Token-ring, ATM, or Fiber Distributed Data Interface (FDDI)

Metro Ethernet is a service which is provided by ISPs For example, MAN can help an organization to connect all of its offices in a city.

Backbone of MAN is high-capacity and high-speed fiber optics

Wide Area Network (WAN) Wide Area Network (WAN) covers a wide area which may span across

provinces and even a whole country.

These networks provide connectivity to MANs and LANs.

Since they are equipped with very high speed backbone, WANs use very expensive network equipment.

WAN may use advanced technologies such as Asynchronous Transfer Mode (ATM) Frame Relay and Synchronous Optical Network (SONET)

Storage Area Network (SAN) It is a dedicated network that provides access to consolidated, block level data

storage

SANs are used to enhance storage devices, such as  disk arrays tape libraries optical jukeboxes

Accessible to servers so the devices appear like locally attached devices to the operating system

A SAN has own network of storage devices not accessible through the local area network (LAN) by other devices

Network Architecture Depending upon its architecture network can be various types such as

Client-Server peer-to-peer or hybrid

There can be one or more systems acting as Server. Other being Client, requests the Server to serve requests.

Server takes and processes request on behalf of Clients

A server computer can manage several clients simultaneously,

One client can be connected to several servers at a time, each providing a different set of services.

Peer to peer (P2P) Two systems can be connected Point-to-Point, or in back-to-back fashion

They both reside at the same level and called peers.

Peers share resources amongst each other

No use of a centralized administrative system

Internetwork A network of networks is called an internetwork, or simply the internet

The internet connects all WANs and it can have connection to LANs and Home networks

Internet uses TCP/IP protocol suite and uses IP as its addressing protocol

It uses WWW, FTP, email services, audio and video streaming etc

Internet works on Client-Server model

Internet uses very high speed backbone of fiber optics

Intranet An intranet is a network based on TCP/IP protocols (an internet)

belonging to an organization, usually a corporation

Accessible only by the organization's members, employees, or others with authorization.

An intranet's firewall blocks unauthorized access

Extranet An extranet is a private network uses Internet technology and the public

telecommunication system

It securely share business's information or operations with suppliers, vendors, partners, customers, or other businesses

An extranet can be viewed as part of a company's intranet that is extended to users outside the company

VPN – virtual private network It is a network is constructed using the Internet to connect private network

such as a company's internal network

only authorized users can access the network and data cannot be intercepted

It is provides a secure, encrypted tunnel to transmit data between remote user and company network