Simulators give students an opportunity to experience network problems at first hand

Playpen network provides fail-safe interactive training.

Playpen network provides fail-safe interactive training.

In preparation for the first lunar landings in 1969 Nasa astronauts practised their manoeuvres using a console hooked to a simulator. By manipulating the data used for the simulations, Nasa scientists were able to assess how the astronauts coped.

This was the inspiration behind Colin Pattinson's approach to teaching future network managers who attend his BSc and MSc courses at Leeds Metropolitan University.

He believed the way network management was being taught was too classroom-based. In a live network, the manager will monitor network traffic and nodes and looks for anomalies.

"While it is not too difficult talking about network trends and deviations, there is a gap when trends and deviations are put into practice," he said.

Pattinson's first attempt at breaking out of the classroom was what he described as a "playpen" network. This network contained a few nodes and allowed students to practise management for real. However, the playpen could not simulate a large network and building one would have been impractical, so Pattinson looked at how he could create a network simulator.

His work led to the development of simulated "model agents" which produce SNMP (Simple Network Management Protocol) formatted data. This creates the illusion that the network messages are coming from real network devices.

The simulations can be controlled to allow tasks to be graded by difficulty, allowing the user to receive increasingly greater exposure to more complex and sensitive elements in the network.

Pattinson presented the idea at an Association of Computer Machinery special interest group meeting in Barcelona in 1996. Since then about seven MSc project students have helped him develop the simulator, which is now used in the networking course curriculum. "In this academic year 60 students have used the system," he said.

There was a lot of interest in the simulator at this year's CeBIT show in Germany. Pattinson believes his approach is unique and, with government support from Business Trade International, the university hopes to forge commercial partnerships.

The benefit of the simulator is that it gives a fairly realistic simulation of the kind of situations that will occur on a network, Pattinson said.

The students are exposed to failures and faults across a wide range of networks and device types. Dedicated screens show the build-up and causes of a fault situation and show what distress signals the system will send out to enable an early diagnosis.

Pattinson has developed several test scenarios, including a crashed node and router table corruption where the path through the network is lost; congestion on the network causing buffer overflows; failure on a network card where the replacement card has a different network address and so may not be detected correctly; and failure by applications to pick up TCP-IP messages.

Another area Pattinson's students are researching is a hacking simulation, such as a denial of service attack. "Network managers need to know the type of messages they will see if a denial of service occurs," he said.

The simulator allows students to manage highly complex networks where failure can be catastrophic. "As systems become more and more complex and the risks attached to their failure become potentially more serious, this simulation offers a fail-safe route to ensuring that all users are up-to-speed before they are ever put in control," he said.

Pattinson collects data on the tasks network administrators undertake when the system is running under normal conditions. When the simulator creates a failure, data is collected that show the steps taken by the students to resolve the problem.

Pattinson hopes to build up a record of activities network administrators always carry out on a network. This can then be used to benchmark how the students respond to a network failure. "We are looking to create a system to learn how a network manager should respond to any given event," he said.

A spin-off project at the university aims to evaluate effective network management by monitoring keystrokes. By collecting this data and playing it back, students can examine the steps they took to resolve a network issue and see where they could work more quickly.

For the past three years, students on the BSc course have had to undertake a timed test where they have just one hour to collect a set of data about the network.

This simulator is based on a fixed network, but Pattinson expects mobile networks to present new and unique challenges.

CV: Colin Pattinson   

Colin Pattinson is principal lecturer in computing at Leeds Metropolitan University. Along with the network simulator he is overseeing several other research projects. One is a study of the data and information transfer requirements of computer integrated manufacturing networks.  

Pattinson believes there are significant gains to be made from treating networks as a resource to be managed. He aims to apply the tools and techniques of network performance management to this area. 

The other area being researched by the computer communications research team at Leeds Metropolitan University is quality of service issues in multimedia applications.

What is BTI?     

British Trade International is a government organisation established to support the UK's trade and investment strategy. It brings together the work of the Foreign and Commonwealth Office and the Department of Trade & Industry on trade development and promotion of inward investment in the UK. BTI's two operating units are Trade Partners UK, which aims to help companies trading overseas and Invest UK, which aims to promote the UK as a worthwhile location for inward investment.

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