A Cisco Education Tool Accessible to the Vision Impaired
J. Hope, B.R. von Konsky, I. Murray, L.C. Chew, B. Farrugia,
Curtin University of Technology
Perth, Western Australia
i.murray@ece.curtin.edu.au
ABSTRACT
This paper describes iNetSim, a universally accessible network
simulator, created to allow vision-impaired and sighted users to
complete Cisco Certified Network Associate level two (CCNA 2)
laboratory sessions. Previously, software used in the CCNA
course was not accessible to those with impaired vision because it
utilized images of network topology. These images were
incompatible with screen reader software. In contrast, iNetSim is
assessable by blind and vision impaired users, in addition to those
with normal vision. It is based on Mac OS X Tiger, an operating
system with an integrated screen reader called VoiceOver.
Categories and Subject Descriptors
H.5.2 [Information Systems]: Interaction styles (e.g., commands,
menus, forms, direct manipulation), Voice I/O
K.4.2 [Social Issues]: Assistive technologies for persons with
disabilities
General Terms
Design, Human Factors.
Keywords
Vision-impaired, Screen readers, Universal Access, User
interfaces, assistive technologies.
1. INTRODUCTION
In 2004, Curtin University commenced a pilot program to teach
vision impaired students industry standard certification courses
[1]. Vision-impaired students taking the Cisco Certified Network
Associate (CCNA) course have limited access to the traditional
learning resources due to the visiocentric nature of the materials.
In particular, Packet Tracer (cisco.netacad.net) is a Macromedia
Flash application that uses images, not text, to display
information. As screen readers do not work with Packet Tracer,
only sighted students can use it. To overcome this limitation, the
iNetSim application described in this paper was developed to be a
“universally accessible” network simulator for use by both
sighted and vision-impaired students.
2. DEVELOPMENT ENVIRONMENT
On April 29, 2005, Apple Computer Inc. released Mac OS X
Tiger version 10.4. This release included VoiceOver [2], a
system wide screen reader designed to provide full computer
functionality to vision-impaired users. Mac OS X includes the
Cocoa API [3] that allows rapid development of complex
applications, and Core
Data [4], which reduces the time required to implement an
application’s document back-end. As a result of these features,
Mac OS X Tiger was chosen as the programming and execution
platform for iNetSim.
3. SPECIFICATION
iNetSim is intended to replace Packet Tracer, allowing vision-
impaired and sighted students to complete CCNA level 2 (Routers
and Routing Basics). For CCNA 2, “students will develop skills
on how to configure a router, manage Cisco Internetwork
Operating System (IOS) Software, configure routing protocol on
routers, and set the access lists to control the access to routers.”
[5]
All user interface and network topology elements are reachable
with VoiceOver keys and provide a meaningful response when
read by VoiceOver.
3.1 Topology Design
The system represents network devices including routers,
switches, hubs and PCs. Input of device configuration data is
required for simulation.
Each device may have several ports of different types including
Ethernet, serial and console. The user creates a connection by
specifying two ports to connect and a cable type. Removing a
connected port disables the connection the same way unplugging
a cable would in a real network.
3.2 Network Simulation
A command line interface to devices provides control and
feedback over the simulation. The interface acts in a similar way
to the operating system for that device type (e.g. a generic DOS-
like system for PCs and Cisco IOS for routers). A subset of the
commands applicable to CCNA 2 allows the user to display and
modify device configuration, establish routing protocols and ping,
Traceroute or telnet to other devices. iNetSim maintains a
representation of routing tables to simulate these tasks correctly.
As an educational tool, iNetSim aims to simulate the results of
these tasks as close to the real systems as possible. Extensibility is
important, as iNetSim will need to adapt to higher CCNA levels
in future.
4. USER INTERFACE DESIGN
Accessibility for the vision impaired drove the design of iNetSim.
Network simulators usually depend on the use of a mouse to add
simulated communication links between devices. To connect two
devices with a communications link, the user must generally click
on icons for the simulated devices. As this may be a problem for
vision-impaired users, iNetSim also incorporates the use of tables
for connecting devices. Tables are used to alter a device’s location
in the topology area, and configure ports and links. Tables are
Copyright is held by the author/owner(s).
ASSETS’06, October 22-25, 2006, Portland, Oregon, USA.
ACM 1-59593-290-9/06/0010.
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used because navigation can be achieved with VoiceOver shortcut
keys and cursor keys. iNetSim can be used solely with the
keyboard, therefore the eye and hand issues faced by vision-
impaired students can be avoided. As a GUI is also available,
sighted iNetSim users can alternatively use a more traditional
drag-drop mouse-based interface.
Figure 1 shows an example of the user interface in iNetSim. The
text in the floating window in the figure shows the text read by
VoiceOver.
Figure 1: The user interface showing interaction with
VoiceOver
4.1 VERIFICATION
A totally blind user took part in a beta test of iNetSim. The user
successful completed the two CCNA 2 laboratories in the test,
even though he was unfamiliar with the material in those
modules. During a post-test interview, the subject indicated that
he was impressed with iNetSim’s ease of use.
Tools capable of discovering accessibility problems are available
for use by application designers. However, usability issues for
specific disabled users are still difficult to assess because
available tools fail to consider usability criteria to particular
vision-impaired people [6][7]. Each tool has a varying level of
completeness (how many checkpoints from accessibility
guidelines are covered), correctness (how well false positives,
where the issue identified is irrelevant or wrong, are reduced) and
specificity (number of different possible issues detected) [8].
Involving representative users in field testing, prototyping and
evaluation will generally lead to better usability[9].
Verification of the final interface using the Accessibility Verifier ,
revealed few issues. These issues were missing descriptors
(AXDescription), and were trivial to fix.
Tests with vision impaired subjects and the results from the
available accessibility tools, show that iNetSim is accessible and
simple to use, allowing vision-impaired users to complete selected
CCNA 2 laboratories.
5. CONCLUSIONS
Assistive design choices made in the early stages of development
lead to a better quality product. The constraints imposed by the
screen reader required a well-designed graphical user interface.
Having a representative user assist with prototyping, development
and evaluation provided insight into usability issues for the
vision-impaired. iNetSim is a fully accessible network simulator
that allows vision-impaired CCNA 2 students to complete
network topology laboratory sessions.
6. ACKNOWLEGEMENTS
The authors would like to acknowledge the support of the Apple
University Consortium for the provision of several Apple
computers utilized in this project.
7. REFERENCES
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http://www.educause.auckland.ac.nz/interactive/index.cfm?a
ction=papers
[2] Apple Computer Inc., 2005, Apple – Mac OS X – VoiceOver,
Retrieved: June 1, 2005, from
http://www.apple.com/macosx/features/voiceover/
[3] Apple Computer Inc., 2005, Cocoa, Retrieved: June 1, 2005,
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[4] Apple Computer Inc., 2005, Developing with Core Data,
Retrieved: November 6, 2005, from
http://developer.apple.com/macosx/coredata.html
[5] Cisco Systems, 2004, CCNA 2: Router and Routing Basics,
Retrieved: April 27, 2005, from http://cisco.netacad.net
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[8] Sribunruangrit N, Marque C, Lenay C, Gapenne O 2004,
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