HNDE Lecture note..Labuduwa Galle.. upload by sika

1. Information Technology
III
Lecture 01 – Types of networks

2. 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

3. Classification of Computer Networks
 Computer networks are on various factors
 Geographical span
 Inter-connectivity
 Administration
 Architecture

4. 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.

5. McGraw-Hill Technology Education Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.
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.

6. 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

7. 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.

8. 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.

10. 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

11. 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)

13. 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

15. 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.

16. 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

17. 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

18. 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

19. 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

21. 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