TDC 562: Computer Network Design and Analysis (Internet Engineering)
 Prof. Ehab Al-Shaer, Spring 2009

 


Assignment # 3:

Traffic Modeling and Simulation

 


Due: 28 May 2009, 11:59pm

 

 


A University main network is connected with its remote campus with a fiber link of 30Mbs and 40ms delay. The campus network has a switched network of 10 Mbps, and 5ms delay. The main campus has the DB server, and Video streaming (e.g., Course-On-Line). The following is the description of the traffic characteristics for each server used in the University network.

 

2. Database Application Traffic

The remote campus send DB queries to the main campus to information. The DB uses TCP for delivering the data reliably to/from the branches. The query and the result (DB records from the server) average sizes are 20 KB and 200 KB, respectively, based on Pareto distribution. The average (user) thinking time is 7 second and the average processing time of the query is 3 second. This is applied for the query and results TCP connections. There are typically three simultaneous DB clients at any given time. The packet size is 1 KB.

 

4. COL Application Traffic

On average there are 2 COL sessions simultaneously initiated from clients in the remote campus and COL traffic will come back from main campus. Each session contains of two different traffic types:

  • MPEG-2 Video: VBR traffic, sending 5 frames per second, average frames size is 20 KB exponentially distributed, packet size is 1000, and the encoder (shaper) sending rate is 1 Mbps.
  • MPEG-2 Audio: CBR traffic, packet size is 512, sending rate is 0.4 Mbps

Video and audio are transported using UDP.

 

Application/Traffic Scenario

Assume that DB starts firsts then COL application at 10 second of the simulation. Run the simulation for 25 seconds.

 

 

Questions

 

  1. What is the average throughput for each application (aggregated for all clients) in every second (20%)?
  2. What is the “utilization” of the core links, and the edge networks in the direction from server to clients (notice that 10 Mbps links means 10Mbps in both directions) during the simulation time (20%)?
  3. Network Capacity Planning (60%):  Study the results in the above questions and do more analysis to identify the network bottlenecks that could exist in the University network, if any, and suggest solution(s).  Justify your proposals.

 

Important Hints

-         Look at the traffic generator description in ns and the calculation of traffic parameters in class notes.

-         The node numbers in nsBench are not similar to the node ids in the NS trace file. The node id of every nsBench node is printed when you run the TCL script.

 

Submission

Submit your homework as ONE FILE only thru DLWEB. DO NOT send emails. Your submission must include:

 

  1. A word doc that contains tables and description of all traffic specifications you use for each application including description of your calculation (how did you derive these values)
  2. Graphs/charts that answer the above questions

 

NO LATE ASSIGNMENT WILL BE ACCEPTED AFTER THE DUE DATE