Faculty & Research, Harvard Business School

Dr. Sayeed Ghani

Associate Dean, Faculty of Computer Science

B. Understanding Queuing

Exercise No. 3 - Queue Animation

  • Based on Section 3.3, pg 75, "Queue Animation" of the Qualnet-4.5.1-User Guide, construct a 4 Node Wired LAN based simulation
  • Conduct the simulation to achieve the following result of the simulation run.
  • This video demonstrates the queuing of packets on a slow link. Two priorities of traffic (p1 and p2) share the link 3-4. Note that the third (leftmost queue) represents p0 which is not present. The p1 queue fills up first as it is of lower priority. p2 queue empties first as it is of higher priority.
  • Note: It seems there is a mistake in the User Guide, where it refers to p2 as non real time (pg 77). Since p2 seems to have the highest priority it should be real time, and p0/p1 which seem to have lower priority should be non real time.(needs verifications)



Exercise No. 4 - M/D/1 Queue simulation

  • Construct an M/D/1 queue with the simulation as demonstrated below with the following details: 2 Nodes linked with a wired 1 Mbps link; VBR application from Node 1 to 2 with 512 Byte fixed size packets, and inter-arrival time exponentially distributed with specified average inter arrival time
  • The M/D/1 equation for Average Waiting Time in queue is: 

  • To calculate average service time you need to add 56 Bytes of overhead: UDP-8+IP-20+MAC/Phy-28 to the 512 Byte VBR packet to total 568 Bytes of transmitted.
  • Conduct the simulation as demonstrated below.



Exercise No. 5 - M/M/1 Queue simulation

  • Construct an M/M/1 queue with the simulation as demonstrated below using the Traffic-Gen application.




Exercise No. 6 -  WiMax simulation

  • Based on Chapter 8, pg 31, "WiMAX Scenario" of the Qualnet-4.5-Product Tour, construct a WiMAX network for any city of your choice. The Demo below is for Karachi, showing 2 handovers performed as a car moves from one end of the city to another, while connected using a 400 Kbps CBR connection to an office.



Exercise No. 7 -  High Speed Mobility