Visual Learning Tools for Teaching/Learning Computer Networks

Transcription

1 2010 Sixth International Conference on Networking and Services Visual Learning Tools for Teaching/Learning Computer Networks Cisco Networking Academy and Packet Tracer Jozef Janitor, František Jakab Regional Cisco Networking Academy Computer Networks Laboratory Technical University of Košice Košice, Slovakia Karol Kniewald Cisco Networking Academy Cisco Systems Czech Republic Prague, Czech Republic Abstract Teaching and learning more abstract subjects, such as computer networks, where higher level of student s imagination is necessary to understand advanced topics can be positively supported trough a technique called visual learning. Students can more easily understand and adapt the information from the subject, when they can visually see how it really works. Teachers can present the subject using animations and practical examples, rather than just talking about theory facts. This paper presents the features of a visual learning tool called Packet Tracer a computer networks simulator, which is freely available for all Cisco Networking Academy students. Packet Tracer, Cisco Networking Academy, Visual Learning, Emerging Teaching Methods, Animation, Simulation, Teaching I. INTRODUCTION Understanding and learning about the functionality of complex computer networks is generally an advanced task. It takes lot of time and energy that students have to invest into their studies. Computer based animations can help students to much more quickly understand and memorize the functionality of different networking protocols and the basic principles of exchanging, or forwarding information from a source towards a destination. Even though, there are many powerful tools like Adobe Flash, etc., that enable quick and easy creation of computer animations, creating a simple animation can still takes several hours of work. Therefore, instructors or teachers usually do not intend to create these animations. On one side, as it was stated above, it requires time spent with the animation development; furthermore, it is necessary to know how to create these animations in different applications. Hands on lab experiences with practical configurations are essential when learning about computer networks. Many times, students are starting to clearly understand the facts only when they are faced with real world cases in the lab environment with networking equipment. While the more time students spend in the lab, the better understanding of complex networking knowledge at the end, with big groups of students, it is often challenging to find a free timeslot in the already tight lab schedules. When students do not experience enough time with practical configurations, they are achieving worst results. Tools like Packet Tracer provide a solution that addresses both issues that were introduced in the text. They are very likely used among students or teachers in Cisco Networking Academies, as they enable easy, yet powerful simulation of computer networks. These tools usually enable a direct look inside of a wire that is interconnecting devices between each other and carries the information flows. Students can visually see and therefore more easily understand what is really going on in the network, how are computers and networking devices exchanging an message from a source host towards the destination. This paper presents how Cisco Networking Academy instructors and students can use Packet Tracer 5.2 to make their teaching and learning experience much more productive and enjoyable. II. VISUAL LEARNING As in [1] Visual Learning is the use of graphics, images and animations to enable and enhance learning in science and engineering. Visual learning is a proven method in which ideas, concepts, data and other information are associated with images and animations, while the subject is represented graphically. As an example, techniques and tools such as webs, mind maps and animations are used in visual learning to enhance thinking and learning skills. Students can understand subjects much more easily if they can see, or even touch them in real. Visual learning uses methods that help students to open their minds and think graphically. Associations between images and some sort of information can help to better memorize and use the learned knowledge or information. III. CISCO NETWORKING ACADEMY We live in an increasingly connected world, creating a global economy and a growing need for technical skills. Cisco Networking Academy [4] delivers information technology skills to over 600,000 students a year in more than 165 countries worldwide. Networking Academy students have the opportunity to participate in a powerful and consistent learning experience that is supported by high quality, online curricula and assessments, instructor training, /10 $ IEEE DOI /ICNS

2 hands-on labs, and classroom interaction. This experience ensures the same level of qualifications and skills regardless of where in the world a student is located. Networking Academy students will become the architects of the networked economy; enabling everyday experiences on the global human network. With the ever-increasing demand for their skills, Networking Academy students have the chance to dream about business-critical positions never before imagined, in industries ranging from medicine and finance to entertainment and aerospace. Networking Academy opens doors to rewarding careers and opportunities for economic advancement and local community development. Students only need to be Mind Wide Open to possibilities [2]. Cisco Networking Academy courses [8] consist of theoretical online learning materials, practical hands on experiences in labs and skills exams. As hands on experiences and lab activities are very important part of networking education, students are requested to spend in the lab environment as much time, as it is possible. Unfortunately, the price of the lab equipments is usually very high [7]. Smaller academies may have lower resources and cannot afford to buy a single device per student. Students have to share access to devices among themselves, or they are using older and slower devices with fewer features available. In addition, access to labs is usually permitted only during official class hours [9]. To overcome these issues, and to provide better teaching and learning experiences with interactivity and animations, the Cisco Networking Academy developed a tool called Packet Tracer. IV. PACKET TRACER Packet Tracer is a self-paced, visual, interactive teaching and learning tool implemented in a form of computer networks simulation software [5]. It is designed to increase interaction between students and instructors, promote student learning, and enhance instructor presentations. It offers a unique combination of realistic simulation and visualization experiences, complex assessment and activity authoring capabilities, and opportunities for multiuser collaboration and competition. Packet Tracer can be used to teach and learn complex networking concepts and to supplement lab equipments. Packet Tracer provides a simulated environment where processes between various networking devices, such as routers, switches, wireless access points, computers, links and applications are visible with animations and easy explanatory descriptions. Students can more easily understand the functionality of different networking devices and networking protocols, when they see the big screen with every event that occurs in real networks. The most important attribute, from the learning and teaching point of view are the various supported features [5]: Many networking protocols Multiple platform support Logical and Physical Workspaces Real-Time and Simulation Modes User friendly CLI Global event list (packet sniffer) LAN, switching, TCP/IP, routing, and WAN protocols Activity Wizard, Lab grading Multiple language support Integrated Help and Tutorials Multiuser Capability Application Programming Interface Packet Tracer in version 5.2 supports the following networking protocols: New security protocols: IPSec and GRE VPNs, IPS and Zone-based policy firewalls on ISRs, AAA, wireless security, SNMP, syslog, NTP New Quality of service (L2 and L3) L7: HTTP, DNS, TFTP, DHCP, Telnet, SSH L4: TCP and UDP L3: IPv4, IPv6, ICMPv4, ICMPv6, ARP, static routing, RIPv1/v2, EIGRP, OSPF L2/L1: Ethernet, a/b/g/n, HDLC, PPP, Frame Relay, SLARP, CDP, STP, RSTP, VTP, DTP, LACP, PAgP Packet Tracer in version 5.2 is available for the following platforms and operating systems: Windows (2000, XP, Vista, 7) Linux (Ubuntu, Fedora) A. Logical and Physical Workspaces The Logical and Physical Workspaces feature displays various networking equipment and devices (fig. 1,2) and interconnections between them. Students can either see how networking devices are distributed throughout various physical locations (geographical areas, cities, buildings, rooms, etc.), or how are they logically connected in the logical topology view (fig. 3). Students can understand differences between physical and logical topologies when they are moving devices between different physical or logical locations. A good example of using the physical workspace view is Wireless Networks. Wireless Access Points cover with wireless radio signal only a small circle like area (few meters) around them. Students learn that if a computer with wireless network cards are not placed in the physical region with wireless radio signal coverage, the computer will not get network access. Figure 1. Physical Topology View Intercity View 352

3 Figure 2. Physical Topology View Wiring Closet View B. Real-Time or Simulation Mode The Real-Time or Simulation Mode is used to create network topologies and to simulate processes inside the created topology. The real-time mode simulates a real environment, with the same speed of simulated networks and protocols as in real situations. If some operation for a simulated protocol in Packet Tracer in the real world takes 30 seconds, it takes a similar time also in the Packet Tracer simulation. New devices can be easily added to the real-time topology just by dragging them from a devices toolbar and dropping them to the real-time logical topology view. The device toolbar contains various devices divided into groups of routers, switches, end devices, etc. Connectivity tests based on simple ping PDU tests, or more advanced application specific PDU tests are available to check whether the connectivity between two or more end devices is working properly. When switching into the simulation mode (fig. 3), Packet Tracer displays the actual data exchange between devices. Each packet, or frame, that carries some data is displayed as a small envelop moving on a link between devices. Step by step packet or frame tracing is supported, while in each step, students can see explanations of what is happening with the carried data on different layers of the ISO OSI model. It is also possible to define filters, so only protocols that are interested for a simulation will be displayed in the topology. Figure 3. Logical Topology View Simulation Mode C. User friendly CLI The User friendly CLI is one of the greatest features of Packet Tracer. Networking devices from the enterprise world are usually managed and configured through a command line interface (CLI). When learning how to manage and configure networking devices, students have to learn and get familiar with many different CLI commands, each with list of valid parameters. Packet Tracer provides a CLI wizard mode (fig. 4), where students can configure a device in a more first-time-user-friendly, graphical intuitive interface, simply by clicking on different settings in the wizard mode. When a new setting is applied by the wizard, a list of commands that were used to configure the new setting it is displayed in the commands window. In this way, students can learn new command line commands and parameters, even if they are using the wizard mode, while at the same time they are not getting disappointed when they just cannot recall some command. When configuring directly in CLI mode, Packet Tracer simulates a CLI of real devices with more or less the same functionality. Figure 4. CLI Wizard D. Global event list The Global event list (packet sniffer) is a feature of Packet Tracer that is part of the simulation mode. The global event list displays each exchanged data between two or more devices. When using the packet sniffer feature, after clicking on an data exchange event represented by an envelope in the logical topology or on the event itself in the event list window, the data PDU (Protocol Data Unit) that was being exchanged between devices is displayed in a new window. Students can review the processes that are happening with the PDU at each ISO OSI layer. For each layer, Packet Tracer contains a clear text explanation of the layer functionality, while describing the details of a PDU forwarding processes towards its destination. The packet sniffer feature can also display the PDU s contents in their graphical representation. E. Protocols Several LAN, switching, TCP/IP, routing, and WAN protocols are simulated by Packet Tracer. Although the simulated protocols list is quite huge, and with every new major release of Packet Tracer new protocols are added, 353

4 there are still some protocols or features that are not yet supported by Packet Tracer. On the other hand, already in its version 5.2, Packet Tracer can be used for almost every lab task required to cover the CCNA level, CCNA Security level, and even some parts that are required on the CCNP level. F. Activity Wizard The Activity Wizard is a feature that enables teachers to create assignments, or even practical exams for students [8]. Teacher can enable the activity wizard mode from the top menu of Packet Tracer. After starting the activity wizard, it is necessary to define an initial starting and a final topology. They can be imported from previously saved files, or created from the scratch. When both the initial starting and the final topology are ready, a teacher can start working on an evaluation process. Differences between the initial starting and the final topology are displayed in a window, where the teacher can select which parts should be evaluated at the final grading. The assignment can be divided into several levels, while each level can contain instructions that explain the task of the level and lead students to the solution. To make sure that students will not get the correct answers just by looking at the final topology, the complete assignment, that was created in the activity wizard can be password protected before it is distributed to students. When a student opens the Packet Tracer Activity file on his computer, a list of instructions and the starting topology is displayed. Assignments can be also limited to a predefined time. After a student has completed all levels and tasks, or the exam s time has expired, he can click on the Grade button and his work will be evaluated and points for each successfully completed task will be added to his score. G. Multiple languages The Multiple language support enables to create your own localized version of Packet Tracer. Every text part of the Packet Tracer GUI can be easily translated with a tool that is distributed together with Packet Tracer. By default, only the English localization is available after a clean installation. New languages can be installed simply by copying a language definition file to a directory where the Packet Tracer was installed. H. Integrated Help and Tutorials The Integrated Help and Tutorials provide step-by-step guides for new users of Packet Tracer. For more advanced features, like the activity wizard, these tutorials are very handy. The integrated help files also contain a small explanation of several networking protocols and their functionality. I. Multiuser Capability The Multiuser Capability was introduced with the release of Packet Tracer in version 5.0. People around the World that are connected to the Internet, or generally to any IP data network, used to play together online games for ages [3]. Packet Tracer brings the same kind of challenging multiuser gaming environment into the process of learning about computer networks. With the multiuser capability of Packet Tracer, students can cross-connect their Packet Tracer applications and create one big topology. Each student is then responsible for its own part of the topology, while they are together trying to achieve a goal a working big simulated network. This feature brings a creative and collaborative work method and builds a team play-work between students. Multiuser competition makes the whole process of learning more enjoyable and exciting. Figure 5. Activity Wizard Figure 6. Multiuser running on 3 computers J. Application Programming Interface The Application Programming Interface and External Applications (API and ExApps) is more or less a new new feature that was introduced already in Packet Tracer 5.0. The open Packet Tracer API interface enables developers to can create their own addons to Packet Tracer. The API provides access to almost every function of Packet Tracer, so skilful developers can create very creative applications that can interact with Packet Tracer in any way. For example, while the whole simulated environment in Packet Tracer is only virtual, now it might be possible to create an external application that will integrate the simulated topology built in 354

5 Packet Tracer, with real devices and real topologies in the lab. Team work of students can be also extended by integrating Packet Tracer with general instant messaging (IM) applications, or with integrating IM directly to Packet Tracer. V. PRACTICAL RESULTS A. From Technical University of Košice Packet Tracer has already been used for many years between the teachers and the students of the Regional Cisco Networking Academy at Technical University of Košice [2]. With the previous releases prior the 4.0 version, Packet Tracer was used more or less only by teachers during the lectures. Primarily, it was used to explain some networking concepts in an animated and visual form. The real tipping point was reached with the release of Packet Tracer in version 4.0. In the 4.0 version, the whole Packet Tracer was rewritten from the scratch by the Cisco Networking Academy PT developers team, and new features, new user interface and a whole new working concept was introduced. The adoption phase of the new Packet Tracer release was very quick. It has started to be used by the students as a replacement or as an add-on to the real devices. The Regional Cisco Networking Academy at Technical University of Košice hosted and has been involved in the preparation of several international competitions in the field of computer networks (e.g. Cisco Olymp, Networking Academy Games). Packet Tracer was used within these competitions as a competing platform in at least one of the categories. Currently, Packet Tracer is used at almost every lecture or exercise. Students are using Packet Tracer on their own home computers to practice network configurations and to gain hands-on skills, while teachers are using Packet Tracer to prepare skills exams and assignments for students. Many final skills exams are currently made in the classroom only with Packet Tracer. The evaluation process with Packet Tracer s built in Activity Wizard became much easier and faster so students get their pass/fail results immediately. In a survey that was completed by students studying computer networks in the winter semester of year 2009, 95% of students said that they have installed Packet Tracer on their home computer or laptop, while 75% of them were using Packet Tracer at least once per week. When asked about functionality differences between real devices and Packet Tracer, 90% of students said Packet Tracer was sufficient enough for their needs. This lowered also the pressure on the lab schedule, as only students with advanced topics visited the lab in free timeslots to get hands on experiences with real devices. On the other hand, surprisingly, during compulsory exercises in labs, when students had a chance to use real devices, only 5% of them wanted to use Packet Tracer instead of real devices. VI. CONCLUSION Packet Tracer is comprehensive networking technology teaching and learning software with innovative features that help students and teachers collaborate, solve problems, and learn concepts in an engaging and dynamic social environment. It makes teaching and learning networking technology easier and more enjoyable with a multiuser network simulation environment. It extends the learning experience with a realistic simulation and visualization environment that is used for exploration, experimentation and explanation. Instructors and students can create their own virtual networking islands for teaching and learning networking concepts and technologies. Packet Tracer solves also situations when the lab environment does not contain enough equipment for the students. Students can use Packet Tracer even on their home computers and do practical homework and gain hands on experiences without even visiting the lab. Anytime, anywhere with Packet Tracer. With Packet Tracer students can more easily understand complex computer network topics in visual representation of processes that are going on in the network. Visualization of these processes makes it easier to understand their roles in the environment of computer networks. Packet Tracer is available for all Cisco Networking Academy students and instructors for free. REFERENCES [1] Visual Learning in Science and Engineering, ACM SIGGRAPH/Eurographics Workshop on Computer Graphics Education held June 2-5, 2004, in Hangzhou, China. [2] Jakab František, Janitor Jozef: Visual Learning: Case Study of Cisco Networking Academy's PACKET TRACER 5.0 Application, Proc. of 6th International Conference on Emerging elearning Technologies and Applications, ICETA 2008, Stara Lesna, , Kosice, elfa, s.r.o., 2008, ICETA, pp , ISBN [3] Janitor Jozef, Jakab František, Kleinová Katarína, Biňas Miroslav, Révés Martin, Jakab Michal: Communication Challenges in elearning solutions, 5th Int. 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