Copyright © 2005 OPNET Technologies, Inc. Confidential, not for distribution to third parties.
Teaching with OPNET Software
Dr. Vasil Y. Hnatyshin
Department of Computer Science
Rowan University
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Course Overview List of Topics and textbooks Software Tools and Projects
OPNET IT Guru and Modeler Laboratories Teaching with IT Guru
Advantages Disadvantages
Alternative IT Guru Lab Manual style Idea Advantages/disadvantages Simple Example
Teaching with OPNET modeler Conclusions
Outline
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Course Overview: List of Topics
“TCP/IP and Internet Technologies”, Spring 2005 W. Stallings, "Computer Networking with Internet Protocols and Technology" List of Topics:
Introduction: OSI and TCP/IP reference models Encapsulation and TCP/IP header format
TCP internals: Reliability and Congestion control TCP flavors: Tahoe, Reno, New Reno, SACK, Vegas
IP internals: IP addressing, subnets and CIDR IPv4, ICMP, and IPv6
Internet Technologies and Quality of Service: Traffic regulation and Token bucket Scheduling and Queue Management: FIFO, PQ/TPQ, WRR/WFQ, RED Integrated and Differentiated Services
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Course Overview: Tools and Projects
TCPDump: Study of network characteristics Number of TCP vs UDP packets Number of TCP SYN and FIN packets Packet Size distribution Use of TOS byte Use of TCP options
OPNET Modeler Implementation of Bandwidth
Distribution Scheme
OPNET IT Guru: TCP vs. UDP: influence of different
transport protocols on application and network performance
TCP Flow Control: influence of window size, MTU, and other parameters on application and network performance
TCP Throughput: influence of window size, MTU, and other parameters on application and network performance
QoS: Impact of Queuing Policy: influence of different queuing mechanisms on delay, jitter, and traffic loss
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OPNET IT Guru and Modeler Laboratories
OPNET IT Guru: Laboratory manuals by Leann Christianson and Kevin Brown to accompany
Data and Computer Communications and Business Data Communications by William Stallings Lab #2: TCP and UDP Introduction Lab #4: TCP Parameters for Flow Control TCP Internals Lab #7: TCP throughput TCP Internals Lab #5: QoS: Impact of Queuing Policy Technologies & QoS
OPNET IT Guru Tutorials: Introduction to IT Guru Introduction Small Networks
OPNET Modeler: OPNET Modeler Tutorials:
Small Networks Basic Processes M/M/1
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Advantages of using IT Guru in the class
Students understand the course material better:Excellent illustration of numerous networking concepts such as:
TCP’s slow start, congestion avoidance, fast recovery/fast retransmit
Better understanding of the importance of the protocol configuration parameters.
Hands-on experience in configuring and setting up simple network configurations
Increased student’s enthusiasm
Simple to download and install IT Guru software
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Disadvantages of using IT Guru in the class
Lack well-fitting laboratory manuals* The laboratory manuals never follow the course outline Laboratory assignments often confusing
Difficult to achieve the same results as those shown in the manual Different versions of the ever-changing software
Following laboratory instructions step-by-step does not facilitate learning
Initially: Difficult to explain how to use IT Guru to the students Significantly more work for the instructor
*Based on the Laboratory manuals by Leann Christianson and Kevin Brown to accompany Data and Computer Communications and Business Data Communications by William Stallings.
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Disadvantages of using IT Guru in the class
Available OPNET IT Guru laboratory manuals Data and Computer Communications by W. Stallings, manual by L.
Christianson and K. Brown Business Data Communications by W. Stallings, manual by L. Christianson
and K. Brown Business Data Networks and Communications by R. Panko Computer Networks – A Systems Approach by Peterson & Davie, IT Guru tutorials OPNETWORK tutorials on the web
But the topics covered in class vary from instructor to instructor and almost always requires more.
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Disadvantages of using IT Guru in the class
Laboratory assignments often too simple and too confusing, why?
Laboratory assignments consists of Step-by-step configuration instructions Questions regarding collected results
Problems with this approach: Requires no thinking during configuration part Lab manual’s IT Guru version may be different from actual software Easy to make a mistake Simulation results often incorrect or different from those in the manual
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Alternative Lab Manual style
Have two sets Laboratory manuals IT Guru tutorials that introduce students to software basics Actual laboratory assignments
The laboratory assignments would consists of Topology/Applications/Protocols configuration specifications No explicit step-by-step instructions Questions about collected results
Students will submit:
Summary of configuration steps Answers to the question Laboratory project files
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Alternative Lab Manual style
Advantages Will require student thinking during configuration phase Configuration errors and incorrect results are easier to track as
the students provide the summary of their configuration steps Easier to write and change lab manuals Software updates have less effect on the labs More work for the students Hopefully less work for the instructor
Disadvantages May be difficult for students to learn how to use IT Guru More work for the students
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Alternative Lab Manual style: Example
Lab: TCP Flow Control – Topology configuration
Node E-mail Client sends e-mail traffic to node E-mail Server over an IP network. The nodes connected to the network via DS 1 link.Packets traveling through given IP network experience latency which is exponentially distributed and has mean outcome of 0.25 seconds.
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Alternative Lab Manual style: Example
Lab: TCP Flow Control – Protocol/Application Configuration
E-mail Configuration: E-mail size: 1 MByte for all messages E-mail interarrival time: exponentially distributed with mean outcome of 100 seconds E-mail application always generates messages in groups of 3.
Client’s Application configuration: Application Type: E-mail Application start time: uniformly distributed between 100 and 110 seconds Application end time: End of simulation Number of concurrent applications: 1
TCP configuration: Maximum Segment Size: 512 bytes Receiver Buffer: 8760 bytes Other parameters: default values
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Alternative Lab Manual style: Example
Lab: TCP Flow Control – Assignment
Examine E-mail application performance: Download Response Time Upload Response Time Traffic Sent Traffic Received
Examine TCP performance parameters: Application data Delay Retransmission Count Segment Delay
1. Repeat the study with the values of TCP receiver buffer values of 16K, 32K, 64K.
2. Repeat the study with the TCP Max Segment size values of 1024 and 2048 bytes, Receiver buffer size is set to 32 K.
Plot, compare, and explain obtained results.
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Teaching with OPNET Modeler
Learning OPNET Modeler Tutorials Documentation Code Endless one-on-one sessions
Outcome: Better understanding of the router internals Two working implementations of the Bandwidth Distribution Scheme A published paper:
“Influence of the discarding the out-of-profile packets policy on TCP traffic," In Proceedings of the 2005 International Conference on Parallel and Distributed Processing Techniques and Applications (PDPTA'05)
Using OPNET Modeler in the undergraduate course is difficultEasier to use it as group research projects such as independent study
and senior project
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Summary and Conclusions
There is need for additional OPNET IT Guru laboratory Manuals
Alternative ways to structure and present the IT Guru manuals
Yet,OPNET IT Guru is an excellent software tool that facilitates the classroom learning process
Using OPNET Modeler at the undergraduate level is possible but is better suited for outside-the-classroom research projects
There are no laboratory manuals for OPNET Modeler
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THE END
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