Copyright © 2005 OPNET Technologies, Inc. Confidential, not for distribution to third parties. Teaching with OPNET Software Dr. Vasil Y. Hnatyshin Department

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

Copyright © 2005 OPNET Technologies, Inc. Confidential, not for distribution to third parties. 2

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


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


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


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


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


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.



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.



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


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


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


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.



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



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.


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


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

Copyright © 2005 OPNET Technologies, Inc. Confidential, not for distribution to third parties.

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Copyright © 2005 OPNET Technologies, Inc. Confidential, not for distribution to third parties. Teaching with OPNET Software Dr. Vasil Y. Hnatyshin Department