1 INTRODUCTION TO COMPUTER NETWORKS (LAN, MAN & WAN) Navpreet Singh Computer Centre Indian Institute of Technology Kanpur Kanpur INDIA (Ph : ,

2 Content Introduction to Computer Networks Physical Media Overview Of Network Architectures Campus Networks Enterprise Networks Internet

3 Computer Networks Computer network connects two or more autonomous computers. The computers can be geographically located anywhere. Introduction to Computer Networks

4 LAN, MAN & WAN Introduction to Computer Networks Network in small geographical Area (Room, Building or a Campus) is called LAN (Local Area Network) Network in a City is call MAN (Metropolitan Area Network) Network spread geographically (Country or across Globe) is called WAN (Wide Area Network)

5 Applications of Networks Introduction to Computer Networks Resource Sharing Hardware (computing resources, disks, printers) Software (application software) Information Sharing Easy accessibility from anywhere (files, databases) Search Capability (WWW) Communication , Chat, VoIP Message broadcast Remote computing Distributed processing (GRID Computing)

6 Network Topology The network topology defines the way in which computers, printers, and other devices are connected. A network topology describes the layout of the wire and devices as well as the paths used by data transmissions. Introduction to Computer Networks

7 QUESTIONS?

8 Network Components Introduction to Computer Networks Physical Media Interconnecting Devices Computers Networking Software Applications

9 Networking Media Networking media can be defined simply as the means by which signals (data) are sent from one computer to another (either by cable or wireless means). Introduction to Computer Networks

10 Networking Devices Introduction to Computer Networks HUB, Switches, Routers, Wireless Access Points, Modems etc.

11 Computers: Clients and Servers In a client/server network arrangement, network services are located in a dedicated computer whose only function is to respond to the requests of clients. The server contains the file, print, application, security, and other services in a central computer that is continuously available to respond to client requests. Introduction to Computer Networks

12 Networking Protocol: TCP/IP Introduction to Computer Networks

13 Applications Searchable Data (Web Sites) E-Commerce News Groups Internet Telephony (VoIP) Video Conferencing Chat Groups Instant Messengers Internet Radio Introduction to Computer Networks

14 QUESTIONS?

15 Physical Media PHYSICAL MEDIA

16 Physical Media

17 Physical Media Copper Coaxial Cable - Thick or Thin Unshielded Twisted Pair - CAT 3,4,5,5e&6 Optical Fiber Multimode Singlemode Wireless Short Range Medium Range (Line of Sight) Satellite Physical Media

18 Copper Media: Coaxial Cable Coaxial cable is a copper- cored cable surrounded by a heavy shielding and is used to connect computers in a network. Outer conductor shields the inner conductor from picking up stray signal from the air. High bandwidth but lossy channel. Repeater is used to regenerate the weakened signals. Physical Media CategoryImpedanceUseRG  Cable TV RG  Thin Ethernet RG  Thick Ethernet

19 Copper Media: Twisted Pair Twisted-pair is a type of cabling that is used for telephone communications and most modern Ethernet networks. A pair of wires forms a circuit that can transmit data. The pairs are twisted to provide protection against crosstalk, the noise generated by adjacent pairs. There are two basic types, shielded twisted-pair (STP) and unshielded twisted-pair (UTP). Physical Media

20 Unshielded Twisted Pair (UTP) Physical Media

21 Unshielded Twisted Pair (UTP) Consists of 4 pairs (8 wires) of insulated copper wires typically about 1 mm thick. The wires are twisted together in a helical form. Twisting reduces the interference between pairs of wires. High bandwidth and High attenuation channel. Flexible and cheap cable. Category rating based on number of twists per inch and the material used CAT 3, CAT 4, CAT 5, Enhanced CAT 5, CAT 6 and now CAT 6+. Physical Media

22 QUESTIONS?

23 Fiber Media Optical fibers use light to send information through the optical medium. It uses the principal of total internal reflection. Modulated light transmissions are used to transmit the signal. Physical Media

24 Total Internal Reflection Physical Media

25 Fiber Media Light travels through the optical media by the way of total internal reflection. Modulation scheme used is intensity modulation. Two types of Fiber media : Multimode Singlemode Multimode Fiber can support less bandwidth than Singlemode Fiber. Singlemode Fiber has a very small core and carry only one beam of light. It can support Gbps data rates over > 100 Km without using repeaters. Physical Media

26 Single and Multimode Fiber Single-mode fiber Carries light pulses along single path Uses Laser Light Source Multimode fiber Many pulses of light generated by LED travel at different angles Physical Media

27 Fiber-Optic Cable Contains one or several glass fibers at its core Surrounding the fibers is a layer called cladding Physical Media

28 Fiber Optic Cable FO Cable may have 1 to over 1000 fibers Physical Media

29 QUESTIONS?

30 Wireless Media Very useful in difficult terrain where cable laying is not possible. Provides mobility to communication nodes. Right of way and cable laying costs can be reduced. Susceptible to rain, atmospheric variations and Objects in transmission path. Physical Media

31 Wireless Media Indoor : 10 – 50m : BlueTooth, WLAN Short range Outdoor : 50 – 200m: WLAN Mid Range Outdoor : 200m – 5 Km : GSM, CDMA, WLAN Point-to-Point, Wi-Max Long Range Outdoor : 5 Km – 100 Km : Microwave Point-to-Point Long Distance Communication : Across Continents : Satellite Communication Physical Media

32 Wireless LAN Physical Media Internet Router Switch Access Point PC

33 Terrestrial Microwave Microwaves do not follow the curvature of earth Line-of-Sight transmission Height allows the signal to travel farther Two frequencies for two way communication Repeater is used to increase the distance Hop-by-Hop Physical Media

34 Satellite Communication Physical Media

35 QUESTIONS?