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Page 1: Top schools in delhi ncr

Top Schools in Delhi NCR

By:school.edhole.com

Page 2: Top schools in delhi ncr

Protocol ArchitectureThe “Common Language”

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Page 3: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

Need for Protocols

Protocols are a set of rules and conventions. By enforcing that communicating parties adhere to a common protocol, communication is made possible.

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Page 4: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

Network Architecture

A Network Architecture is a structured set of protocols that implement the exchange of information between computers

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Page 5: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

Programming the Communication Any complex programming task is made

simpler by using several levels of abstraction

Abstraction hides the programming details of lower levels

Communication tasks give rise to standard abstractions

Committees such as the IETF (Internet Engineering Task Force) are in charge for standardizing the abstractions related to internet communicationschool.edhole.com

Page 6: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

The Levels of Abstraction Multiple levels of communication

abstractions have been defined by standardization bodies

Each level is enforced by a corresponding protocol

Each level uses the abstract services of the level below

Abstraction achieves separation of concerns A protocol needn’t know how the lower-level

abstractions are implemented and what the higher level abstractions are.

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Page 7: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

Layered Network Architecture

In a Layered Network Architecture, the services are grouped in a hierarchy of layers. A protocol of layer N uses only services of layer

N-1. A protocol of layer N provides services only to

layer N+1.A

C

E

B

D E

B layer 3

layer 2

layer 1

not layered layered

A

C

Dschool.edhole.com

Page 8: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

Service Primitives

N+1 LayerEntity

N+1 LayerEntity

N LayerEntity

N LayerEntity

N+1 Layer Protocol

X. Request X. Indication X. ResponseX. Confirm

Assume that some protocol implements service “X”.

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Page 9: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

Service PrimitivesRecall: A layer N+1 protocol entity sees the lower layers only as an abstract service provider

N+1 LayerEntity

N+1 LayerEntity

N+1 Layer Protocol

X. Request X. IndicationX. Confirm

Service Provider

X. Response

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Page 10: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

Example: Sending a Letter

Bob’s mailbox

Bob Alice

Alice’smailbox

Postman

Logical flow of information

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Page 11: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

(Un-)Acknowledged Service

Unconfirmed service:

Acknowledged service:

US Mail

L.Request L.Indicate

L.IndicateL.Confirm

US Mail

L.Request L.Indicate

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Page 12: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

Protocol Architectures There are only few protocol

architectures that are relevant today: OSI Reference Model TCP/IP Protocols Suite ATM Protocol Stack

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Page 13: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

OSI Reference Model The OSI model defines seven layers:

Layer 7: Application LayerLayer 6: Presentation LayerLayer 5: Session LayerLayer 4: Transport LayerLayer 3: Network LayerLayer 2: Data Link LayerLayer 1: Physical LayerInterconnection Mediaschool.edhole.com

Page 14: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

OSI Layers

PhysicalLayer

PhysicalLayer

PhysicalLayer

PhysicalLayer

Data LinkLayer

Data LinkLayer

Data LinkLayer

Data LinkLayer

NetworkLayer

SessionLayer

SessionLayer

TransportLayer

TransportLayer

ApplicationLayer

ApplicationLayer

PresentationLayer

PresentationLayer

NetworkLayer

NetworkLayer

NetworkLayer

Application

HOST

NODE

HOST

NODE

Application

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Page 15: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

OSI Layers and Encapsulation

PhysicalLayer

PhysicalLayer

Data LinkLayer

Data LinkLayer

NetworkLayer

SessionLayer

SessionLayer

TransportLayer

TransportLayer

ApplicationLayer

ApplicationLayer

PresentationLayer

PresentationLayer

NetworkLayer

Application Application

AH

PH

SH

TH

NH

DH

Bits

Data

AH Data

PH AH Data

SH PH AH Data

TH SH PH AH Data

NH TH SH PH AH Data

DataApplication

DataHeader of

ApplicationLayer

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Page 16: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

OSI Model in a Switched Communication Network

Transport

Session

Presentation

ApplicationTransport

Session

Presentation

Application

Physical

Data Link

Network

Physical

Data Link

Network

Physical

Data Link

Network

Physical

Data Link

Network

Physical

Data Link

Network

Physical

Data Link

Network

Station (Host)

Node (Router)

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Page 17: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

A Tour of the OSI Layers Physical Layer (Layer 1):

Converts bits into electrical or optical signals

Transmits these signals over the hardware communication medium

Example: RS-232

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Page 18: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

A Tour of the OSI Layers Data Link Layer (Layer 2):

Reliably transfers frames over a link Performs synchronization, error

control, flow control Example: PPP

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Page 19: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

A Tour of the OSI Layers Network Layer (Layer 3):

Moves packets inside the network Performs routing, addressing,

switching, congestion control Example: IP

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Page 20: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

A Tour of the OSI Layers Transport Layer (Layer 4):

Controls delivery of data between hosts

Connection management, error control, flow control, multiplexing, TCP, UDP.

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Page 21: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

A Tour of the OSI Layers Session Layer (Layer 5):

Support the dialog between cooperating application programs

Session management, synchronization

Example: RPC

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Page 22: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

A Tour of the OSI Layers Presentation Layer (Layer 6):

Data conversion into application format Encryption/decryption Secure sockets

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Page 23: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

A Tour of the OSI Layers

Application Layer (Layer 7): Provides network access to

application programs Everything is application specific Example: File Transfer, Electronic

Mail

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Page 24: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

TCP/IP Protocol Suite The TCP/IP protocol suite

was first defined in 1974 The TCP/IP protocol suite

is the protocol architecture of the Internet

The TCP/IP suite has four layers: Application, Transport, Internet, and Network Interface Layer

ApplicationLayer

TransportLayer

Internet

NetworkInterface

telnet, ftp, email

TCP, UDP

IP, ICMP, IGMP

Device Drivers

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Page 25: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

Example: File Transfer

FTPprogram

TCP

IP

EthernetDriver

EthernetDriver

EthernetDriver

IP

FTPprogram

TCP

IP

EthernetDriver

FTP protocol

TCP protocol

IP protocol IP protocol

Ethernetprotocol

Ethernetprotocol

Host A Router Host B

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Page 26: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

Encapsulation in the TCP/IP Suite

Application

TCP

IP

EthernetDriver

User data

User dataApplicationHeader

Application dataTCP Header

Application dataTCP HeaderIP Header

Application dataTCP HeaderIP HeaderEthernetHeader

EthernetTrailer

IP datagram

TCP segment

Ethernet frameschool.edhole.com

Page 27: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

TCP/IP Protocol Suite

ApplicationLayer

NetworkLayer

Link Layer

IP

ARPHardwareInterface

RARP

Media

ICMP IGMP

TransportLayer

TCP UDP

UserProcess

UserProcess

UserProcess

UserProcess

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Page 28: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

Comparison of OSI Model and TCP/IP Suite

Application

Presentation

Session

Transport

Network

Data Link

Physical

Application

Transport

Internetwork

NetworkAccess

Physical

OSI TCP/IP

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Page 29: Top schools in delhi ncr

Copyright by Jorg Liebeherr 98, 99

Quiz Name one function of the network

layer

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