1. 11/30/2018 Subject Name: COMPUTER NETWORKS I Subject Code: 10CS55
Prepared By: KRISHNA SOWJANYA.K SANTHIYA, SHRUTHI N
Department: CSE
Date: 30/8/2014
11/30/2018

2. Data Communication: Definition
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Data Communication: Definition
Data Communication:
Transfer of data from one device to another via
some form of transmission medium.

3. Data Communication Hi, how are you? Hi, how are you? 01010001 01010001
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Data Communication
Hi,
Hi,
how
how
are
are
you?
you?
Hi, how are you?
Hi, how are you?
Computer

4. Data Communication Characteristics
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Data Communication Characteristics
Delivery
Deliver data to correct destination
Accuracy
Data not alterer or left uncorrected
Timeliness
Data delivery at correct time
Jitter
No variation in packet arrival time

5. Components in Communication
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Components in Communication 1
Message
Hi, how are you? 5
Protocol 2
Sender 3
Receiver 4
Medium

6. Data Representation Numbers Text Images
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Data Representation
Numbers
8/16/32 bit integers
floating point
Text
ASCII, Unicode
Images
Bit patterns, Graphics formats JPG/GIF/etc
Audio  Samples of continuous signal
Video  Sequence of bitmap images
150 2
255

7. Data Flow Simplex: One direction only data flow Server Monitor
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Data Flow
Simplex: One direction only
Server
Monitor
data flow
data flow
Keyboard

8. Direction of Data Flow Half Duplex: Both directions, one at a time
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Direction of Data Flow
Half Duplex: Both directions, one at a time
E.g., walkie-talkies
data flow at time 1
data flow at time 2

9. Direction of Data Flow Full Duplex: Both directions simultaneously
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Direction of Data Flow
Full Duplex: Both directions simultaneously
E.g., telephone
Can be emulated on a single communication link using various methods
data flow
data flow

10. Networks Network: a set of devices connected by media links Laptop
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Networks
Network: a set of devices connected by media links
Media Links
Printer
Workstation
Laptop
Scanner
Server

11. Network Criteria Performance Throughput Delay Reliablility
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Network Criteria
Performance
Throughput
Delay
Reliablility
Accuracy of delivery
Frequency of failure
Robustness
Security
Protection from unauthorized access
Protecting data from damage and development

12. Types of Connections Point-to-point Multipoint (multidrop)
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Types of Connections
Point-to-point
Multipoint (multidrop)

13. Point-To-Point Connection
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Point-To-Point Connection

14. Multipoint Connection
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Multipoint Connection
Wireless

15. Topology Topology: physical or logical arrangement of devices Mesh
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Topology
Topology: physical or logical arrangement of devices
Mesh
Star
Bus
Ring
Hybrid

16. Fully Connected Mesh Topology
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Fully Connected Mesh Topology
Pros:
Dedicated links
Robustness
Privacy
Easy to identify fault
Cons:
A lot of cabling
I/O ports
Difficult to move

17. Star Topology Pros: Cons: One I/O port per device Little cabling
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Star Topology
Pros:
One I/O port per device
Little cabling
Easy to install
Robustness
Easy to identify fault
Cons:
Single point of failure
More cabling still required
Hub

18. Bus Topology Pros: Cons: Little cabling Easy to install
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Bus Topology
Pros:
Little cabling
Easy to install
Cons:
Difficult to modify
Difficult to isolate fault
Break in the bus cable stops all transmission

19. Ring Topology Pros: Cons: Easy to install Easy to identify fault
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Ring Topology
Pros:
Easy to install
Easy to identify fault
Cons:
Delay in large ring
Break in the ring stops all transmission

20. Engineered for Tomorrow
Hybrid Topologies

21. Network Categories Local Area Network (LAN) Wide Area Network (WAN)
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Network Categories
Local Area Network (LAN)
Wide Area Network (WAN)
Metropolitan Area Network (MAN)

22. Local Area Networks Network in a single office, building, or campus
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Local Area Networks
Network in a single office, building, or campus

23. Engineered for Tomorrow
Wide Area Networks
Network providing long-distance communication over a country, a continent, or the whole world

24. Metropolitan Area Networks
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Metropolitan Area Networks
Network extended over an entire city
Bangkhen
Kampangsaen

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Internetworking
How to allow devices from different standards to communicate
Gateways/routers – devices capable of communicating in several standards
These become "network of networks"

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Internetworks
Two or more networks connected become an internetwork, or internet
Example: The Internet
Network1
Network2
Gateway
Network3

27. Protocols and Standards
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Protocols and Standards
Protocol
A set of rules governing data communications
Syntax: format of data block
Semantics: meaning of each section
Timing: speed and sequencing
Standards
De facto (in practice) standards
 not approved but widely adopted
De jure (in law) standards
 approved by an organization

28. Standards Organizations
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Standards Organizations
Creation Committees
International Organization for Standardization(ISO)
International Telecommunication Union- Telecommunication Standards Sector(ITU-T)
AmericanNational Standards Institue(ANSI)
Institute of Electrical and Electronics Engineers(IEEE)
Electonics Industries Association(EIA)
Forums
Regulatory Agencies

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NETWORK MODELS

30. Engineered for Tomorrow
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.

31. Tasks involved in sending a letter
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Tasks involved in sending a letter

32. Logical communication path
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Layer Model
Layer N uses services provided by Layer N-1
HOST A
HOST B
Logical communication path
Layer N
Layer N
Layer N protocol
Using services
Providing services
Layer N-1
Layer N-1
Layer N-2
Layer N-2
Virtual Communication System

33. Why Layers? Guidelines for protocol developments Modularity
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Why Layers?
Guidelines for protocol developments
Reference model
Modularity
Eases maintenance and updating of systems
A change in one layer is transparent to the rest
Is layering always the best thing to do?
Maybe not  cross-layer optimization

34. 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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35. Seven layers of the OSI model
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Seven layers of the OSI model

36. Responsible for transmitting individual bits from one node to the next
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Physical Layer
Responsible for transmitting individual bits from one node to the next
Duties/services
Physical characteristics of interfaces and media
Representation of bits
Data rate (transmission rate)
Synchronization of bits

37. Engineered for Tomorrow
Physical Layer

38. Responsible for transmitting frames from one node to the next
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Data Link Layer
Responsible for transmitting frames from one node to the next
Duties/services
Framing
Physical addressing
Flow control (hop-to-hop)
Error control (hop-to-hop)
Access control

39. Data Link Layer from Network to Network Data Data Data Link Layer T2
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Data Link Layer
from Network
to Network
Data
Data
Data Link Layer T2
Data H2 T2
Data H2
(frame)
to Physical
from Physical

40. Network Layer Duties/services
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Network Layer
Responsible for the delivery of packets from the original source to the destination
Duties/services
Logical addressing
Routing

41. Network Layer from Transport to Transport Data Data Network Layer Data
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Network Layer
from Transport
to Transport
Data
Data
Network Layer
Data H3
Data H3
(packet)
to Data Link
from Data Link

42. Responsible for delivery of a message from one process to another
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Transport Layer
Responsible for delivery of a message from one process to another
Duties/services
Port addressing
Segmentation and reassembly
Connection control
Flow control (end-to-end)
Error control (end-to-end)

43. Transport Layer from Application to Application Data Data
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Transport Layer
from Application
to Application
Data
Data
Transport Layer
Data1 H4
Data2 H4
Data3 H4
Data1 H4
Data2 H4
Data3 H4
(segments)
to Network
from Network

44. Session Layer Duties/services
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Session Layer
Responsible for establishing, managing and terminating connections between applications
Duties/services
Interaction management
 Simplex, half-duplex, full-duplex
Session recovery

45. Presentation Layer Duties/services
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Presentation Layer
Responsible for handling differences in data representation to applications
Duties/services
Data translation
Encryption
Decryption
Compression

46. Responsible for providing services to the user
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Application Layer
Responsible for providing services to the user
Duties/services
Network Virtual Terminal
File transfer, access and management
Mail services
Directory service

47. Engineered for Tomorrow
TCP/IP Protocol Suite
TCP/IP model is also called as the TCP/IP protocol suite. It is a collection of protocols.
The TCP/IP protocol suite is made of five layers: physical, data link, network, transport, and application.
The first four layers provide physical standards, network interfaces, internetworking, and transport functions that correspond to the first four layers of the OSI model.
The Network layer of TCP/IP model corresponds to the Network Layer of OSI model
The Host to network layer of TCP/IP model corresponds to the Physical and Datalink Layer of OSI model.

48. TCP/IP Model User Application Layer Transport Layer Network Layer
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TCP/IP Model
User
Application Layer
Transport Layer
Network Layer
Data Link Layer
Physical Layer
Software
Hardware
Transmission Medium

49. Engineered for Tomorrow
TCP/IP and OSI model

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Addressing
Four levels of addresses are used in an internet employing the TCP/IP protocols:
Physical
Logical
Port
Specific

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Physical Address
Physical Address is the lowest level of addressing, also known as link address.
It is local to the network to which the device is connected and unique inside it.
The physical address is usually included in the frame and is used at the data link layer.
MAC is a type of physical address that is 6 byte (48 bit) in size and is imprinted on the Network Interface Card (NIC) of the device.

52. Logical Addresses are used for universal communication.
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Logical Address
Logical Addresses are used for universal communication.
Logical Address is also called as IP Address (Internet Protocol address).
At the network layer, device i.e. computers and routers are identified universally by their IP Address.
IP addresses are universally unique.
Currently there are two versions of IP addresses being used: IPV4 and IPV^

53. For example TELNET uses port address 23, HTTP uses port address 80
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Port Address
A logical address facilitates the transmission of data from source to destination device.
But the source and the destination both may be having multiple processes communicating with each other.
A Port Address is the name or label given to a process. It is a 16 bit address.
For example TELNET uses port address 23, HTTP uses port address 80

54. Specific Address
Port addresses address facilitates the transmission of data from process to process but still there may be a problem with data delivery.
Again the responsibility of the port address is over here and there is a need of addressing that helps identify the different instances of the same process.
Such address are user friendly addresses and are called specific addresses.
Examples: Multiple Tabs or windows of a web browser work under the same process that is HTTP but are identified using Uniform Resource Locators (URL), addresses.
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