1. Computer Networking A Top-Down Approach Featuring the Internet
Introduction

2. Reference Books
James F. Kurose, Keith W. Ross, “Computer Networking: A Top-Down Approach Featuring the Internet”, 3rd Edition , Pearson Education 2009
William Stallings, “Data and Computer Communications”, Seventh Edition, PHI 2004.
Andrew S. Tanenbaum,”Computer Networks” 4th Edition PHI
B. A. Fourozan, “TCP/IP Protocol Suite”, 3rd Edition, Singapore, McGrawHill, 2004
B. A. Fourozan, “Data Communications and Networking”, 4th Edition, Singapore, McGrawHill, 2004.

3. Roadmap Introduction to Basics Network Models
Computer Network – Components | Classification
Internet
Clients and Servers
Network Models
Protocol Layers - Architecture and Services
OSI – ISO Model
TCP/IP Model
Network Edge: Connection Oriented and Connectionless Services
Network Core: Switching Techniques

4. Communication Model Source Transmitter Transmission System Receiver
generates data to be transmitted
Transmitter
Converts data into transmittable signals
Transmission System
Carries data
Receiver
Converts received signal into data
Destination
Takes incoming data

5. Network Topology
Network topology is the arrangement of the various elements (links, nodes, etc.) of a computer network.
Bus topology
Star topology
Ring topology
Tree topology
Mesh topology
Fully Connected Topology
Partially Connected Mesh Topology

6. Examples

7. Connectivity
Defined as Direct or Indirect access to every other node in the network. Basic Building Blocks are
Links: Coaxial cable, optical fiber...
Nodes: General-purpose workstations...
Connectivity
Indirect Connectivity
Switched Networks (using Switches)
Inter-Network (using Routers)
Direct Connectivity
Point-to-Point (e.g. Bus )
Multiple Access (e.g. Mesh)

8. Example – Direct Connectivity
Concerns: Data broadcast, collisions, media access control
Concerns: Cost vs Simplicity
Addressing concept is needed if we want the receiver alone to consume the packet!

9. Example – Indirect Connectivity
Concerns: One-hop path to any node, reliability, forwarding function
Switch may forward multiple packets in parallel for additional efficiency.
Concerns: Reliability to link failure, near-minimal links
All nodes do “forwarding” and “filtering” .

10. Multiplexing / Demultiplexing
Multiplexing: A method by which multiple analog message signals or digital data streams are combined into one signal over a shared medium.
Cost: waiting time, buffer space & packet loss
Gain: Money => Overall system costs less
Demultiplexing: Exactly reverse process of multiplexing.

11. Sample Network Network A Internet Network B
Modem (Multiplexer/Demultiplexer)
Network C
Router
Switch
Switch
A router is a device that forwards data packets between computer networks, creating an overlay internetwork. A router is connected to two or more data lines from different networks. When a data packet comes in one of the lines, the router reads the address information in the packet to determine its ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey. Routers perform the "traffic directing" functions on the Internet.
A network switch is a computer networking device that links network segments or network devices. It receives a message from any device connected to it and then transmits the message only to the device for which the message was meant. This makes the switch a more intelligent device than a hub (which receives a message and then transmits it to all the other devices on its network).
Switching involves moving packets between devices on the same network. Conversely, routing involves moving packets between different networks.
Network
Sub Net

12. Roadmap Introduction to Basics Network Models
Computer Network – Components | Classification
Internet
Clients and Servers
Network Models
Protocol Layers - Architecture and Services
OSI – ISO Model
TCP/IP Model
Network Edge: Connection Oriented and Connectionless Services
Network Core: Switching Techniques

13. Classification of Network – Size Based
LAN
Example: Ethernet
MAN
Example: Cable TV Network in a City
WAN
Example: Internet - A Network spread in a Continent
Wireless LAN / WAN
Example: Wi-Fi
Example: 3G, WAP, GPRS
Home Networks
Example: ADSL (Cable Modem)
ADSL: Asymmetric digital subscriber line - faster data transmission over copper telephone lines

14. Classification of Network – Size Based

15. Local Area Network - LAN
Example: Small Broadcast networks
Bus
Ring

16. Example: A metropolitan area network based on cable TV.
Metropolitan Area Network - MAN
Example: A metropolitan area network based on cable TV.

17. Relation between hosts on LANs and the subnet.
Wide Area Network - WAN
Relation between hosts on LANs and the subnet.

18. A stream of packets from sender to receiver.
Wide Area Network - WAN
A stream of packets from sender to receiver.

19. Wireless Access Network
It is a shared wireless access network which connects end system to router
via base station aka “access point”
Wired Network
base
station
mobile
hosts
router
Examples:
Wireless LANs:
b/g/n (WiFi) Mbps max raw data rate
Wider-area wireless access
3G - minimum data rate of 2 Mbit/s for stationary and 384 kbit/s in a moving vehicle

20. Home Network Typical home network components: wireless laptops to/from
ADSL or cable modem
Router/firewall/NAT
Ethernet
Wireless Access Point
wireless
laptops
to/from
cable
headend
cable
modem
router/
firewall
wireless
access
point
Ethernet

21. Roadmap Introduction to Basics Network Models
Computer Network – Components | Classification
Internet
Clients and Servers
Network Models
Protocol Layers - Architecture and Services
OSI – ISO Model
TCP/IP Model
Network Edge: Connection Oriented and Connectionless Services
Network Core: Switching Techniques

22. The Internet “Network of networks interconnected by routers”
“A communication medium used by millions”
Applications:
Online data operation (store | retrieve | manipulate) – Banking,, Income Tax
E-Commerce - Shopping , Booking
Communication - , Chat
Knowledge (Static | Dynamic) - Web “surfing”
Entertainment - Streaming media
Note the stress on “single” in the definition of a Computer Network.
It is important to learn that the Internet is an example of yet another network. Network’s don’t mean the Internet!!!
The Web is not a computer network but a distributed application that runs on top of the Internet.
Next, we will get a very quick overview of the Internet.

23. Components of Internet
Hosts (Connected End Systems)
Communication Links (Bandwidth): Fibre Optic, Copper, Radio, Satellite
Intermediate Devices: Hub, Switches, Routers
Data
Internet Service Providers

24. Internetworking - Components
Sub-network – a constituent of Internet
Intermediate system – devices used to support communication between end users of networks.
Bridge | Router

25. Roadmap Introduction to Basics Network Models
Computer Network – Components | Classification
Internet
Clients and Servers
Network Models
Protocol Layers - Architecture and Services
OSI – ISO Model
TCP/IP Model
Network Edge: Connection Oriented and Connectionless Services
Network Core: Switching Techniques

26. Client – Server Concept
A system that respond to a request. OR a system provides service.
Client
A computer or computer program that initiates contact with the server in order to submit a request for required service.
Data, CPUs, printers, and data storage devices are all examples of resources.
There can be n number of clients connected to m number of servers, thereby utilizing the resources concurrently.

27. Network Model - Classification
It defines the category in which a computer network can be grouped into. Two broad categories:
Peer to Peer Model (P2P)
Each computer acts as a client and server.
Allows shared access to various resources such as files, peripherals, and sensors without the need for a central server.
Client – Server Model
Assigns one of two roles to the computers in a network: Client or server.
Offers centralized access to services and devices.

28. Peer – to – Peer Model Advantages Disadvantages Easy to configure.
Easy communication.
Additional server hardware or software not required.
Users can manage their own resources.
Network administrator not required.
Low total cost of network setup.
Limited number of connections for shared resources.
Computers with shared resources suffer from sluggish performance.
Don’t allow for central management.
Users are responsible for managing resources.
Poor security.

29. Client- Server Model Advantages Disadvantages
Best suited for 10 or more users.
Provides sophisticated security.
Administration: - centralized (easier to manage).
New technology can be easily integrated into the system.
Accessibility - Server can be accessed remotely and across multiple platforms.
Cost: More expensive in terms of hardware and network operating system.
Complexity: Experienced system administrators are required to manage the systems.
Dependence: When server goes down, operations will cease across the network.