Computer Network : Lecture Notes Nepal Engineering College Prepared by: Junior Professor: Daya Ram Budhathoki Nepal Engineering college, Changunarayan dayaramb(at)nec.edu.np Available online at http://dayaramb.wordpress.com --------------------------------------------------------------------------------------------------- References: Text book: 1. Computer Networking A Top-Down Approach Featuring the Internet James F. Kurose and Keith W. Ross 2. Data and Computer Communication William Stalling 3. Computer Network A.S Tanenebaum 4. Data communicaton and Networking- Forouzan 5. Microsoft Encyclopedia of Networking 6. IIT Computer Network Video lectures. 7. Wiki-pedia Page: 1 compiled by: JP NEC. Daya Ram Budhathoki Table of Contents Chapter1: Emergence of Network , principle of communication Network and Multiplexing...................7 What is computer Network?..................................................................................................................7 Historical Events:................................................................................................................................8 Modes of communication:.....................................................................................................................9 Protocol:..............................................................................................................................................10 Principle of Communication:..............................................................................................................11 Elements of Network:..........................................................................................................................13 Multiplexing:.......................................................................................................................................14 Simplex:..........................................................................................................................................14 Duplex............................................................................................................................................14 Half-duplex.....................................................................................................................................14 Chapter2: Network Topology and Architecture.......................................................................................15 Local Area Network (LAN)................................................................................................................15 MAN:...................................................................................................................................................15 WAN: ..................................................................................................................................................16 LAN Vs WAN.....................................................................................................................................17 Internet:...............................................................................................................................................17 Intranet:...............................................................................................................................................18 Extranet:..............................................................................................................................................19 Ethernet:..............................................................................................................................................19 Physical Topology and Logical Topology:..........................................................................................20 Bus Topology:.....................................................................................................................................21 Ring Topology.....................................................................................................................................21 Mesh Topology:...................................................................................................................................22 Star Topology:.....................................................................................................................................22 Logical Topology:...............................................................................................................................23 Network Architecture:.........................................................................................................................23 Peer-to-Peer Model:........................................................................................................................23 Client-server Model:.......................................................................................................................24 Wireless LAN:.....................................................................................................................................26 Wireless Standards - 802.11b 802.11a 802.11g and 802.11n.........................................................27 Wireless Topologies:.......................................................................................................................27 Chapter3: OSI Reference Model:.............................................................................................................29 Network Software:..............................................................................................................................29 Protocol Hierarchies............................................................................................................................29 Layer Communication:........................................................................................................................29 OSI Model...........................................................................................................................................30 Peer-to-Peer Communication:.............................................................................................................31 Data Encapsulation:.............................................................................................................................31 Seven Layers of OSI Reference Model:..............................................................................................32 1. Physical Layer:...........................................................................................................................32 2. Data Link Layer:.........................................................................................................................32 3. Network Layer:...........................................................................................................................33 Page: 2 compiled by: JP NEC. Daya Ram Budhathoki 4. Transport Layer:.........................................................................................................................33 5. Session Layer:.............................................................................................................................34 6. Presentation Layer: ....................................................................................................................34 7. Application layer:........................................................................................................................35 Devices and Protocols on each Layer:............................................................................................35 Chapter4: Physical layers and its Design issues:.....................................................................................36 Transmission Medium:........................................................................................................................36 Shielded Twisted-Pair (STP) Cable ....................................................................................................36 Unshielded twisted-pair (UTP) ..........................................................................................................37 UTP Cabling Standards ......................................................................................................................38 Co-axial Cable:....................................................................................................................................38 Coaxial Cable Connectors .......................................................................................................................39 Fiber-optics..........................................................................................................................................39 Fiber Compared to Copper Cabling :..............................................................................................40 Propagation modes:........................................................................................................................40 Advantages and Disadvantages of Optical Fiber ...........................................................................43 Wireless Networking...........................................................................................................................43 Radio Waves ..................................................................................................................................45 Microwaves ....................................................................................................................................45