Network

NETWORK AGB 111 2013-14

Networks Types of Networks • LAN - Local Area Network • WLAN - Wireless Local Area Network • WAN - Wide Area Network • MAN - Metropolitan Area Network • SAN - Storage Area Network, System Area Network, Server Area Network, or sometimes Small Area Network 04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

2

Types of networks (Contd.)

• CAN - Campus Area Network, Controller Area Network, or sometimes Cluster Area Network • PAN - Personal Area Network • DAN - Desk Area Network

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

3

Local Area Networks (LANs) • The Computers are geographically close together.

• LAN is a computer network that spans a relatively small area.

• Most LANs are confined to a single building or group of buildings.

• However, one LAN can be connected to other LANs over any distance via telephone lines and radio waves.

• A system of LANs connected in this way is called a wide area network (WAN).

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

4

Local Area Networks (LANs)-Contd.

• Most LANs connect workstations and personal computers.

• Each node (individual computer) in a LAN has its own CPU with which it executes programs, but it is also able to access data and devices anywhere on the LAN. • This means that many users can share expensive devices, such as laser printers, as well as data.

• Users can also use the LAN to communicate with each other, by sending e-mail or engaging in chat sessions.

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

5

Wide Area Networks (WANs) •

A WAN is a computer network that spans a relatively large geographical area • Computers connected to a wide area network are often connected through public networks, such as the telephone system.

• They can also be connected through leased lines or satellites.

• The largest WAN in existence is the Internet.

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

6

WAN consists of two or more local area networks (LANs).

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

7

LAN/WAN

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

8

The Internet

What is the Internet?

• A world-wide network of computers allows people to share information electronically • Like a BIG book with many web-pages on different topics • Can be accessed anywhere with an Internet connection

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

10

Uses of the Internet • • • • • • • • •

References Apply for jobs or schools Fill out government forms Check bank accounts Communicate with family, friends and co-workers Do research Learn new skills Read news Watch videos

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

11

How to connect to the Internet • Three main ways to connect to the Internet • Dial-Up • High Speed/DSL • Wireless Connection (Wi-Fi)

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

12

Internet Connections • There are various technologies available that you can use to connect a home computer to the Internet – A phone modem converts computer data into an analog audio signal for transfer over a telephone line, and then a modem at the destination converts it back again into data – A digital subscriber line (DSL) uses regular copper phone lines to transfer digital data to and from the phone company’s central office – A cable modem uses the same line that your cable TV signals come in on to transfer the data back and forth

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

13

Dial-Up Internet Connection • Dial-Up • All you need is a computer, phone-line and Internet Service Provider! (ISP) • Not as fast as other Internet connections, but often more affordable

Your computer 04/12/13

Landline

ISP

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

Internet

14

High Speed (Cable/DSL) Internet Connection • Travels through fiber-optic cables underground • Needs to be connected by a Modem to your computer – Modem: A hub that connects the computer to the Internet • Faster than Dial-up

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

15

Internet Connections • Broadband A connection in which transfer speeds are faster than 128 bits per second – DSL connections and cable modems are broadband connections – The speed for downloads (getting data from the Internet to your home computer) may not be the same as uploads (sending data from your home computer to the Internet)

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

16

Broadband

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

17

Internet Service Provider • A company that provides Internet access for customers (examples: Comcast, Qwest, AOL) • Your computer connects to the Internet Service Provider (ISP), then to the Internet

Your computer 04/12/13

ISP Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

Internet 18

Wireless Internet Connection (Wi-Fi) • The computer must be a “Wireless enabled” device • Computer can pick up signals from different wireless networks • Some networks require passwords or a subscription, others are free

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

This is what the wireless symbol would look like if your computer was connected

19

Packet Switching • To improve the efficiency of transferring information over a shared communication line, messages are divided into fixedsized, numbered packets • Network devices called routers are used to direct packets between networks

Messages sent by packet switching

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

20

TCP/IP • TCP stands for Transmission Control Protocol TCP software breaks messages into packets, hands them off to the IP software for delivery, and then orders and reassembles the packets at their destination • IP stands for Internet Protocol IP software deals with the routing of packets through the maze of interconnected networks to their final destination 04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

21

User Datagram Protocol (UDP) • Computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol (IP) network without prior communications to set up special transmission channels or data paths.

– It is an alternative to TCP – The main difference is that TCP is highly reliable, at the cost of decreased performance, while UDP is less reliable, but generally faster 04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

22

TCP/UDP

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

23

High-Level Protocols • Other protocols build on the foundation established by the TCP/IP protocol suite – Simple Mail Transfer Protocol (SMTP) – File Transfer Protocol (FTP) – Telnet – Hyper Text Transfer Protocol (http)

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

24

Hyper Text Transfer Protocol

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

25

MIME Types – MIME stands for Multipurpose Internet Mail Extension – Based on a document’s MIME type, an application program can decide how to deal with the data it is given

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

26

Multipurpose Internet Mail Extension

Simple Mail Transfer Protocol (SMTP) 04/12/13

Post Office protocol Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

27

Some protocols and the ports they use

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

28

Firewalls • Firewall A machine and its software that serve as a special gateway to a network, protecting it from inappropriate access – Filters the network traffic that comes in, checking the validity of the messages as much as possible and perhaps denying some messages altogether – Enforces an organization’s access control policy

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

29

Firewalls

04/12/13

A firewall protecting a LAN Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

30

Firewall protecting LAN and WAN

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

31

IP Addresses • An IP address can be split into – network address, which specifies a specific network – host number, which specifies a particular machine in that network

04/12/13

R. Jayashree, in Asst.four Professorbytes An IP address isDr.stored Veterinary College, Bangalore

32

Network Addresses • Hostname A unique identification that specifies a particular computer on the Internet Example: Saturn and Jupiter may be the hostnames of two devices connected to a network named Alpha Host names: saturn.alpha.net and jupiter.alpha.net. www.kvafsu.kar.nic.in www.uasbangalore.edu.in 04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

33

Host number • Network software translates a hostname into its corresponding IP address For example 205.39.145.18 local network has an address of 192.168.1.0 /30

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

34

Domain Name System • A hostname consists of the computer name followed by the domain name • csc.villanova.edu is the domain name – A domain name is separated into two or more sections that specify the organization, and possibly a subset of an organization, of which the computer is a part – Two organizations can have a computer named the same thing because the domain name makes it clear which one is being referred to 04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

35

Domain Name System • The very last section of the domain is called its toplevel domain (TLD) name

04/12/13

Dr. R. Jayashree, Asst. Professor Top-level domains, including Veterinary some College, relatively new ones Bangalore

36

Domain Name System • Organizations based in countries other than the United States use a top-level domain that corresponds to their two-letter country codes

Some of the top-level domain names based on country codes 04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

37

Domain Name System • The domain name system (DNS) is chiefly used to translate hostnames into numeric IP addresses – DNS is an example of a distributed database – If that server can resolve the hostname, it does so – If not, that server asks another domain name server

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

38

NICNET • It is a nationwide computer communication network set up by NIC, which uses satellite based technology.

NICNET Services • E-Mail • Access to Internet • File Transfer Facility (FTP) • Electronic Bulletin Board

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

39

National Informatic Centre (NIC) • NIC was set up in 1977 as a constituent unit under the Department of Electronics, Government of India to provide computer based informatics services to • Central Government Departments • State Government Departments • Union Territory Administration • District Administration

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

40

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

41

04/12/13

Dr. R. Jayashree, Asst. Professor Veterinary College, Bangalore

42