1. Chapter 1 Introduction to computer network
Introduction to Computer Networks
Chapter 1
Introduction to
computer network

2. Introduction to Computer Networks
A network is a set of devices (often referred to as nodes) connected by communication links. A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network.
By: Jigar M. Pandya

3. Rules For Communication
Introduction to Computer Networks
Rules For Communication
Transmission should take place without error.
Transmission should be Less.
The cost of Transmission should be less.
The message should be safe and secure.
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4. 5 Components For Communication
Introduction to Computer Networks
5 Components For Communication
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5. Data Flow Of Messages Introduction to Computer Networks
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6. Applications of Networks
Introduction to Computer Networks
Applications of Networks
Resource Sharing
Hardware (computing resources, disks, printers)
Software (application software)
Information Sharing
Easy accessibility from anywhere (files, databases)
Search Capability (WWW)
Communication
Message broadcast
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7. Introduction to Computer Networks
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.
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8. Introduction to Computer Networks
Bus Topology
Commonly referred to as a linear bus, all the devices on a bus topology are connected by one single cable.
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9. Introduction to Computer Networks
Star & Tree Topology
The star topology is the most commonly used architecture in Ethernet LANs.
Larger networks use the extended star topology also called tree topology. When used with network devices that filter frames or packets, like bridges, switches, and routers, this topology significantly reduces the traffic on the wires by sending packets only to the wires of the destination host.
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10. Introduction to Computer Networks
Ring Topology
A frame travels around the ring, stopping at each node. If a node wants to transmit data, it adds the data as well as the destination address to the frame.
The frame then continues around the ring until it finds the destination node, which takes the data out of the frame.
Single ring – All the devices on the network share a single cable
Dual ring – The dual ring topology allows data to be sent in both directions.
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11. Introduction to Computer Networks
Mesh Topology
The mesh topology connects all devices (nodes) to each other for redundancy and fault tolerance.
It is used in WANs to interconnect LANs and for mission critical networks like those used by banks and financial institutions.
Implementing the mesh topology is expensive and difficult.
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12. Types of Connection Introduction to Computer Networks
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13. Network Components Physical Media Interconnecting Devices Computers
Introduction to Computer Networks
Network Components
Physical Media
Interconnecting Devices
Computers
Networking Software
Applications
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14. Introduction to Computer Networks
LAN, MAN & WAN
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)
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15. Applications E-mail Searchable Data (Web Sites) E-Commerce News Groups
Introduction to Computer Networks
Applications
Searchable Data (Web Sites)
E-Commerce
News Groups
Internet Telephony (VoIP)
Video Conferencing
Chat Groups
Instant Messengers
Internet Radio
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16. Network Models
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17. Two Types Of Connections are there
Connection Oriented service
Connectionless service
Connection Oriented Service.
Similar to the telephone system
Establish Connection
Use Connection
Release connection.
Connectionless service.
Same as postal service, each message has full add.
Order may differ of delivery.
Five primitives are used.
Listen
Connect
Receive
Send
Disconnect

18. LAYERED TASKS
We use the concept of layers in our daily life. As an example, let us consider two friends who communicate through postal mail. The process of sending a letter to a friend would be complex if there were no services available from the post office.
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19. Tasks involved in sending a letter
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20. THE OSI MODEL
Established in 1947, the International Standards Organization (ISO) is a multinational body dedicated to worldwide agreement on international standards. An ISO standard that covers all aspects of network communications is the Open Systems Interconnection (OSI) model. It was first introduced in the late 1970s.
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21. ISO is the organization. OSI is the model.
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22. Seven layers of the OSI model
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23. The interaction between layers in the OSI model
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24. The physical layer is responsible for movements of
individual bits from one hop (node) to the next.
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25. Data link layer
The data link layer is responsible for moving frames from one hop (node) to the next.
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26. Figure 2.7 Hop-to-hop delivery
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27. the source host to the destination host.
Network layer
The network layer is responsible for the delivery of individual packets from
the source host to the destination host.
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28. Transport layer
The transport layer is responsible for the delivery of a message from one process to another.
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29. Session layer
The session layer is responsible for dialog control and synchronization.
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30. Presentation layer
The presentation layer is responsible for translation, compression, and encryption.
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31. Data translation ,compression and encryption. Encrypt data to hide it.
Presentation layer
Data translation ,compression and encryption.
Encrypt data to hide it.
Compress data from last message to small no of messages.
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32. Application layer
The application layer is responsible for providing services to the user.
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33. Login password checking, file transfer are some of the application.
Application layer
Login password checking, file transfer are some of the application.
Provide direct access to network device.
Interface between user and system. Examples
File transfer s
www
Protocols
ftp, smtp, telnet….
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34. Summary of layers
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35. QUESTIONS What is Connection Oriented Service ?
What Is Connection Less Service ?
Example Of Connation Less ?
Example Of Connection Oriented ?
Full Form Of OSI
Full Form OF ISO
What is OSI Model ?
How many Layers are there in OSI Model ?
Task Of Application layer ?
Task Of Presentation layer ?
Task Of Session layer ?
Task Of Transport layer ?
Task Of Network layer ?
Task Of Data-link layer ?
Task Of Physical layer ?
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36. TCP/IP Model
The layers in the TCP/IP MODEL do not exactly match those in the OSI model.
The original TCP/IP protocol suite was defined as having four layers: host-to-network, internet, transport, and application.
However, when TCP/IP is compared to OSI, we can say that the TCP/IP protocol suite is made of five layers: physical, data link, network, transport, and application.
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37. The TCP/IP reference model.
TCP/IP Model
( Transmission control protocol / internet protocol )
The TCP/IP reference model.
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38. TCP/IP Model
( Transmission control protocol / internet protocol )
IT Was earlier used by ARPA(Advanced Research Project Agency)
Used to connect Military networks together.
Basically work for the internet .
TCP/IP offers a simple naming and addressing scheme.
Info is carried in packets.
IP is used to put message in Packet.
Each packet has address of sender and receiver (IP Address)
Divide large message in to small packets.
It is not necessary for all packets to follow same route.
HTTP helps it to Share HTML Doc with the help of WWW.
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39. Host – to – Network Layer
TCP/IP Model Layers
Host – to – Network Layer
Lowest Layer in model
Combination of Physical and Data-link Layer.
The host has to connect to the network using some protocol, so it can send IP packets over it.
Protocol may vary based on host or network.
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40. TCP/IP Model Layers Internet Layer
It holds whole architecture together.
The task is to insert packet into any network and make them travel.
The order of packets may differ ,the higher layer support it to arrange packets.
It Defines Packet format and protocol called IP.
Routing of packets and congestion control are important issues.
Almost same as the network layer in OSI model.
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41. TCP/IP Model Layers Transport Layer
Same Function as Transport layer in OSI layer.
It allows entities to converse with each other.
The Protocols Used Are TCP & UDP.
TCP is Connection Oriented Service, No Error ,Handles Flow of control.
UDP is Connection less service, Chances Of Error , Prompt delivery is more important then accurate.
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42. TCP/IP Model Layers Application Layer
IT Doesn't Have Session or Presentation Layer.
All upper level protocols are supported by This layer.
Main task is to provide user interface.
Provide services that can be used by other services.
For Example .
SMTP :- Mailing Service
Telnet :- Remote Logon Service
FTP :- File Transfer Service.
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43. TCP/IP and OSI model
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44. Comparing OSI and TCP/IP Models
Concepts central to the OSI model
Services
Interfaces
Protocols

45. Comparing OSI and TCP/IP Models
Why OSI did not take over the world
Bad timing
Bad technology
Bad implementations
Bad politics

46. Comparing OSI and TCP/IP Models
Problems In TCP / IP :
Service, interface, and protocol not distinguished
Not a general model
Host-to-network “layer” not really a layer
No mention of physical and data link layers
Minor protocols deeply embedded, hard to replace

49. Hybrid Model

50. Design Issues For Layers
Addressing - whom am I going to talk to? i.e., how do we identify senders and receivers?
Rules for data transfer: Simplex ,half-duplex and full duplex
Error control: This is all about communicating along imperfect channels and error correction in such cases.
Large messages: Procedures for disassembling, transmitting and reassembling.