Final PPT 02 April 2012

8/2/2019 Final PPT 02 April 2012

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Presented By:Retaish Wali

Neha Arya

SIMULATION OFDATA LINK LAYERARQ TECHNIQUES

Progress Report

Final Yr Project


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Introduction

Our project titled Simulation Of Data Link Layer ARQTechniquesis aimed at simulating the actions of datalink layer in controlling the data flow and errors by

Automatic Repeat Request (ARQ) .

About Data Link Layer

Layer-2 of OSI model of networking

Framing

Physical addressing

Error and Flow control

Frame Synchronization


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Resource Requirements

Hardware Specifications :

Processor : 1.6GHz or faster

RAM : 1 GB (32 Bit) or 2 GB (64 Bit) RAM

Hard Disk : 3GB of free spaceResolution : 1024 x 768 or higher

Software Specifications :

Operating System : Windows Environment

Front End : Visual Studio 2010


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Module Classification

There are three modules in our project

1. Stop and Wait

2. Go Back N3. Selective Repeat


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1. Stop And Wait

Mechanism of Stop and Wait ARQ technique

1. Sender : STOP after transmitting a single frame & Wait for ACK

2. Receiver : Receive correct frame & Transmit acknowledgment(ACK)

3. Sender : ACK received before timeout : Go to Step 1.

Else

Re-transmit the frame


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2. Go Back N

Mechanism of Go Back N Flow technique

1. Sender : Send no. of frames specified by a Window Size

No wait for ACK

2. Receiver : Transmit acknowledgment(ACK) for correct frame received

Else

Discard frames & transmit Negative ACK (NAK)

3. Sender : Only ACK sreceived: Go to Step 1

Else

Re-transmit the damaged/Lost ACK frame & its followers


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3. Selective Repeat

Mechanism of Selective Repeat Flow technique

1. Sender : Send no. of frames specified by a Window Size

No wait for ACK

2. Receiver : Transmit acknowledgment (ACK) for correct frame received

Else

Discard frames & transmit Negative ACK (NAK)

3. Sender : Only ACK sreceived: Go to Step 1Else

Re-transmit only damaged /Lost ACK frame


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Snapshot


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Simulation of error/flow technique thus aims at assuring safety intransmitting data.

Selective Repeat has advantage over Go Back N that N-fewer

re-transmissions occur but carries a disadvantage of more complexity at

sender and receiver

Go Back N sends multiple frames equivalent to window size(N)but

single NAK leads to retransmission of N-frames.

Stop and Wait is simple to implement but inefficient due to wastage of

bandwidth in transmitting duplicate frames.

Conclusion


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QUERIES ?

Thank You

Documents

Final PPT 02 April 2012