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Opnet – Lab Review

Opnet – Lab Review. ENTC 345 Dr. Ana Goulart Assistant Professor. Lab#1 – Tutorial on M/M/1 Queue. Review the main steps New project New node New network (with a single node) Statistics Configure Simulation Analyze the results. Run Simulation. View and Analyze Results. Create

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Opnet – Lab Review

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  1. Opnet – Lab Review ENTC 345 Dr. Ana Goulart Assistant Professor

  2. Lab#1 – Tutorial on M/M/1 Queue • Review the main steps • New project • New node • New network (with a single node) • Statistics • Configure Simulation • Analyze the results Run Simulation View and Analyze Results Create Network Models Choose Statistics

  3. Create Network Models • We had to create a New node model in Node Editor. • We had to create New network (with a single node) in Project Editor

  4. Create Network Models New node Node Editor Create Processor Source Create Processor Queue Create Processor Sink Create Packet Streams Verify Node Interfaces Save

  5. Create Network Models Project Editor Add the new node model to a Custom Palette Create New Network With a single node Save

  6. Choose Statistics Specify Network Model Probe Editor Set probes Save Create node statistic probe Create node statistic probe Choose object (queue) Choose object (queue) Statistic: Queue delay Statistic: Queue size

  7. Simulation Sequence Editor Run Simulation DES Configure DES (Advanced) Set Duration, Seed Create a Simulation Scenario Outputs – Statistical Collection (Probe File) Save

  8. Analysis Tool View and Analyze Results Analysis Configuration Queue size Choose network model And output statistics • As Is • Average • Time Average Queue delay

  9. Create Network Models Now, let’s go back to the node editor: New node Create Processor Source • Generates packets • The attributes are: • Name = src • Process model = simple_source • Packet Interarrival time • exponential • mean outcome = 1 • Packet Size • exponential • mean outcome = 9000 bits Create Processor Queue Create Processor Sink Create Packet Streams Verify Node Interfaces Save

  10. For example, Packet inter-arrival time: • Exponential, mean outcome = 1 means: Poisson process, with rate λ = 1 packet/sec L x time The exponential random variable X, with parameter λ. The PDF is given by fX(x) = λe-λx f(x) x 0 1 2

  11. Exponential PDF fX(x) = λe-λx f(x) x 0 1 2 x1 x1 Probability (interarrival time ≤ x1) = ⌠ λe-λx dx 0

  12. Example of other PDF options: • Packet size = constant • Packet size = uniform distribution • Packet interarrival time = constant • Packet interarrival time = normal distribution f(x) f(x) x x 1 1 There are several PDFs (probability density function) to choose from. Then we would have a different process (not necessarily an M/M/1 queue model).

  13. Create Network Models New node Create Processor Source • Represent queue and service • The attributes are: • Name = queue • Process model = acb_fifo (first in / first out) • Service rate = 9600 bits/sec Create Processor Queue Create Processor Sink Create Packet Streams Verify Node Interfaces Save

  14. Create Network Models New node Create Processor Source • To delete packets and save memory • The attributes are: • Name = sink Create Processor Queue Create Processor Sink Create Packet Streams Verify Node Interfaces Save

  15. Create Network Models New node Create Processor Source To interconnect the modules Create Processor Queue Create Processor Sink Create Packet Streams Verify Node Interfaces Save

  16. Create Network Models New node Create Processor Source Because of details of Opnet implementation Create Processor Queue Create Processor Sink Create Packet Streams Verify Node Interfaces Save

  17. Create Network Models Now, let’s review the Project Editor Add the new node model to a Custom Palette Create New Network With a single node Save

  18. Create Network Models Now, let’s review the Project Editor Add the new node model to a Custom Palette Create New Network With a single node Save

  19. For Lab#2 (2nd part): An exercise to understand the delays and collisions in Ethernet networks Consider a 100-m optical fiber link operating at 1Gbps. The velocity of propagation of optical fiber is typically about 2 x 108 m/s. Assume a frame of 1000 octets (8000 bits). a) What is this frame’s transmission time? b) What is the propagation time? c) How many bits on the link when a stream of bits fully occupies the link?

  20. Example B A to First bit of the frame B A to + tprop …. Llink B A to+ tx …. Last bit of the frame

  21. Example And finally, all bits are transmitted and received B A to + tprop + tx last bit of the frame

  22. One more example – Now for 10Mbps Ethernet R= 10Mbps D= 100m V=2x108m/s L = 8000 bits (packet size) a) What is this frame’s transmission time? b) What is the propagation time? c) How many bits on the link when a stream of bits fully occupies the link?

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