Final Presentation

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Line Protocols Package for OPNET

• Final Presentation
• Written by 
• Firas Amer Morad Kiwan
• Project Supervisor
• Nir Arad

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Project Goals

• Building models for two well known line protocols
  (Stop And Wait Go Back N) by using the OPNET
  developing environment.
• Running some simulations on the models and
  comparing the results to the theory.

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Project General Description

• 
  
• Our goal is to communicate between the two
  nodes Host0 and Host1.
• The hosts operate as a transmitter and receiver
  simultaneously.
• They will communicate by the stop and wait line
  protocol and the go back N line protocol.

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Project Background

• Stop and Wait
• Transmits a Data Packet and then waits for a
  response.
• The receiver receives each Data Packet and sends
  an Acknowledgement (ACK) if it received
  correctly, and a Negative Acknowledgement (NACK)
  if it was not received correctly.
• The transmitter will implement a timer to recover
  from the condition where the receiver does not
  respond.

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An example is shown next
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Go Back N

• the sender is allowed to transmit multiple
  packets without waiting for an Ack but is
  constrained to have no more than some maximum
  allowable number N of unacknowledged packets.
• the protocol relies upon a protocol timer in the
  local node to detect that no acknowledgment was
  received.

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An example is shown next
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The project Editor
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Packets Format
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Stop And WaitHost0 and Host1 Module
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Data Link Process
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Statistics

• All packets sent.
• Packets sent successfully.
• Packets received successfully.
• Received acks.
• Queue size.
• Waiting time.
• Arrived packets.
• Number of sends.

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Example 1

• Just Gen1 is allowed.
• Ber0.
• Time out 5.
• Packet size3000bits.
• Packet interarrival time is constant ,1packet per
  second.
• Data rate 1000 bit/sec.

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Cont
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Example 2

• Just Gen1 is allowed.
• Ber 1.
• Time out 5sec.
• Packet size3000bits.
• Packet interarrival time is constant ,1packet per
  second.
• Data rate is 1000 bit/sec.

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Cont
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Example 3

• Just Gen1 is allowed.
• Ber 0.0008.
• Time out 5sec.
• Packet size3000bits.
• Packet interarrival time is constant ,1packet per
  second.
• Data rate is 1000 bit/sec

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Cont
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Simulations and results

• Scenario1
• In this scenario just Gen1 is allowed to produce
  Data packets with an exponential distribution
  (Poisson process) with parameter LAMBDA 1. The
  packet size is 500 bits.
• There are no errors in the link between the two
  hosts. The data rate is 1000 Per second.
• The timeout of the host is 5 seconds.

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After running the simulation, we got the
following results
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As illustrated in the figures above

• Arrived packets is not constantly distributed.
• Queue size is acting according to Arrived
  packets and Received acks.
• Number of sends is always 1 because there are
  no errors.
• Waiting time also is acting according to Queue
  size.
• N 1 0.72 0.72, we got 0.78, the results are
  close.

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Scenario2

• In this scenario the both generators are allowed
  to produce Data packets, but there is a
  probability of bit error ber 0.0008.
• Gen0 produces 1 Data packet per 5 seconds. The
  packet size is 300 bits.
• Gen1 produces 1 Data packet per 6 seconds. The
  packet size is 500 bits.
• The data rate of the wire is still 100 bit/sec.
• The timeout of the two hosts is 5 seconds.

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After running the simulation, we got the
following results
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Cont
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Cont
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Cont
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As illustrated in the figures above

• As a result of existing errors, some packets have
  been sent several times.
• The number of sends is different between the two
  hosts because the probability of error in sending
  a packet is related to its size, the size of the
  packets at host1 is larger so the number of sends
  is bigger.
• The queue size is also different in the hosts
  because it is related to the distribution of the
  arrival time of packets.

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Go Back N Host0 and Host1 Module
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Data Link Process
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Statistics

• All packets sent.
• Packets sent successfully.
• Packets received successfully.
• Received acks.
• Queue size.
• Waiting time.
• Arrived packets.
• Number of sends.
• Window.

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Example 1

• Just Gen1 is allowed.
• Ber0.
• Time out 10.
• Packet size1000bits.
• N8.
• Packet interarrival time is constant ,1packet per
  second.
• Data rate 1000 bit/sec.

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Cont
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Example 2

• Just Gen1 allowed is allowed.
• Ber1.
• Time out 10.
• Packet size1000bits.
• N8.
• Packet interarrival time is constant ,1packet per
  second.
• Data rate 1000 bit/sec.

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Cont
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Example 3

• Just Gen1 allowed is allowed.
• Ber0.0008.
• Time out 10.
• Packet size1000bits.
• N8.
• Packet interarrival time is constant ,1packet per
  second.
• Data rate 1000 bit/sec.

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Cont
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Simulations and results

• Scenario1
• N8 and, Timeout 10sec
• In this scenario just Gen1 is allowed to produce
  Data packets with a constant distribution of 1
  Data packet per 3 seconds. The packet size is 500
  bits.
• Delay 10sec.

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After running the simulation, we got the
following results
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As illustrated in the figures above

• timeout is small consequently the host will be
  forced to resend each Data packet 3 times.
• The window is moving between 1 and 8 as a result
  of the resend actions.

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Scenario2

• In this scenario both generators are allowed to
  produce Data packets to send for the other side.
  The parameters are given next
• Gen0 produce 1 Data packet every 8 seconds, the
  size is 1024 bits.
• Gen1 produce 1 Data packet every 13 seconds, the
  size is 500 bits.
• N8 and Timeout10sec
• Ber0.001

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After running the simulation, we got the
following results
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The End