Protocol Simulation Testbed


Outline of Research

The Communications Group of the Faculty of Computer Science,
University of New Brunswick, Fredericton, NB, Canada is
currently involved in the development of a universal Protocol 
Simulation Testbed. Although commercially available software-
based protocol testbeds are available, they are generally 
oriented to network evaluation and planning and lack the 
flexibility required for use as a research tool for protocol 
design, testing and verification.

	Participating in this research and development work are 
(in alphabetical order) Dr. Aziz Al-Zoman (formerly Ph.D. student), 
John M. Dedourek (Professor), Dr. Bernd J. Kurz (Professor) and 
Adam Reece (MCS student). 

	During the past few years we have developed a software-
based simulation testbed to simulate the 7-layer OSI protocol
stack for (currently) point-to-point communication and
evaluate the performance of protocol suites. This is a very
flexible and modularized model which allows quick exchange
of protocol layers (testing what-if scenarios), traffic
loads generated by statistical or deterministic generators
(with data from measured sessions), and the definition of
digital channel media with many error types injected by
statistical error generators (statistical models or from
measured data), such as for cellular telephone and satellite

	The testbed software is written in C with the simulation 
library package SMPL, and runs under AIX on a RS6000 work 
[Diagram of Protocol Testbed]

	Currently available protocol layers are HDLC in
many versions, including our own enhanced HDLC version, as
well as channel models for cellular telephone links. Also 
available is ATM with a newly-developed AAL5 interface to HDLC, 
and a Satcom channel model for upcoming research work.

	Recent research work carried out on the Protocol 
Simulation Testbed deals with the development of a robust 
HDLC protocol for harsh error environments, and for the 
evaluation of ATM over Satellite

A New Face for our Protocol Testbed

The Protocol Testbed was developed as a versatile research tool. As such it requires a code manipulation and recompilation process every time the protocol stacks are changed. Although this code manipulation is made easy due to the modular design of the testbed software, amounting essentially to shifting out a previous protocol layer software module and shifting in a new one, this was nevertheless a time-consuming and error-prone process. Currently, work is in progress to develop and design a graphical front end to the testbed which allows a user-friendly configuration of the protocol stacks. Using drag-and-drop methods, (sub)protocols can be selected from a pool of available (sub)protocol modules and moved into the protocol stacks at both ends of the simulated point-to-point communication system. Certain protocol configuration parameters can also be specified at this time. The GUI front-end interchanges its configuration specification with the existing testbed via a configuration file, which in turn, contains hooks into the testbed's internal software structure. The Protocol Testbed will be started from the graphical front end and automatically configure itself as specified prior to running a simulation session. The addition of this GUI configuartion front-end will make the Protocol Testbed more readily usable in repetitve 'what-if' scenarios, and will help speed up our research on protocol design and performance evaluation considerably. We have chosen Java (with GUI builder) as the language of implementation for the testbed's GUI. This will allow us to operate the testbed from our local workstations, and also ultimately make the testbed available to remote operators via the WWW. This is our first step to establishing a telepresence of our laboratory equipment for research telework. This work is carried out jointly by Dr. Bernd J. Kurz (Professor), John M. Dedourek (Professor) with the assistance of Bruce Ashfield and Poorang Irani, undergraduate Honors students. Project Status: Started: November 1991 Completed: Testbed April 1995, GUI Front End April 1997,

Relevant Publications

Ashfield, Irani: A Graphics Shell for a Protocol Simulation 
  Testbed, CS4997 Honors Thesis, Fac. of Computer Science, 
  Univ. of New Brunswick, April 1997, 102 pages
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Last revised: 6 June 1997 by Bernd Kurz bjkurz@unb.ca