1. Identification of VNEL Web Access Experiment System WAES

The goal of the WAES is to support a Master's program in Network Engineering with facilities capable of demonstrating ideas and concepts and allowing students freedom to experiment through Internet.

Figure 1

This document describes the design for the Virtual Network Engineering Lab (VNEL) Web Access Experiment System (WAES). Refer to "The Users' Guide to WAES"[PDF] for more information. Note: it is still a work in progress.

2. WAES' Overview - VNE Lab and Architecture

WAES is an experiment providing and user behavior controlling system. It provides the capacity for the users to remotely conduct their experiments. At the meantime, it controls the behavior of the users during an experiment session.

WAES is an experiment grading assistant system. It can log the actions and results of the experiments to assist the instructor to do grading. Furthermore it can intelligently evaluate the result of some simple experiments and do grading automatically.

WAES is an experiment schedulable system, which allows the users to schedule their experiment time under experiment valid period.

WAES is an experiment oriented management system. It helps to manage and maintain users' personal information, experiment materials and resources etc.

WAES is an experiment design assistant system. It provides the possibility that the instructors can design and submit their experiments remotely.

WAES is a modular distributed system. All of its modules can be integrated in single or multiple machines and multiple copies of the same module can be activated in different machines the different places currently. The properties of the distributing let the system have scalability, reliability and performance balancing attributes.

WAES is a performance guarantee system. Besides the experiment devices, the network bandwidth and the server machines' capacity are also considered limited resource by the system. The system will evaluate the current utilization of the resources before it admits a new experiment request.

WAES is a multi-session and multi-user experiment system. A user can apply and run multiple different experiments at the same. Furthermore multi-users can real-timely collaborate to complete the same experiment. These properties let the system more flexible and friendly.

view larger image

Figure 2 WAES Architecture

3. WAES' Components and Functions Web Access Experiment System WAES consists of following software modules:

  1) Web Browser 
  2) Java Applet Telnet Client (JATC) 
  3) Web Server
  4) Web Access Gateway (WAG) 
  5) Experiment Manager (EM) 
  6) Experiment Session (ES) 
  7) Device Manager (DM) 
  8) Device Configuration Agent (DCA) 
  9) Device Proxy Server (DPS) 
 10) Database (DB) 

Here is the brief description of the components' functions:

The Web Browser is the user point of contact with the system, which displays the user interface menus for interaction with the WAES and the interpreter of the Java Applet Telnet Client.

The Java Applet Telnet Client (JATC) consists of experiment control client and telnet client. The experiment control client is used to receive information from and send control request to the Experiment Session. The telnet client is used to provide remote terminals to the devices through the Experiment Session (ES).

The Web Server is the server point of contact with the system.

The Web Access Gateway (WAG) is a group of CGI alike applications that process request from the users. It consists of three sub-components according to the classification of users: student sub-component, instructor sub-component and administrator sub-component. Web Access Gateway must work with the Web Server. Each of the sub-components is comprised of several modules. WAG is one of most complicated and time-consuming parts in the system.

The Experiment Manager (EM) is the part that manages and maintains a group of the active experiment sessions. The Experiment Manager dynamically creates and passes initial information to an experiment session once the user attempts to start one experiment. During the Experiment, EM may pass the requests, which is submitted through browser by the User, from WAG to Experiment Session.

The Experiment Session (ES) is an active experiment orient part, which handles most of the interactions between the user and devices during the experiment.

The Device Manager (DM) is a component that manages the device resources, like reserving resources, instructing the Device Configuration Agent (DCA) to initialize and reset the configuration of the devices and releasing or collecting device resources.

The Device Configuration Agent (DCA) is the part that receives configuration initialization or reset request with certain information from the Device Manager, conduct the request and sends the result status to the Device Manager.

The Device Proxy Server (DPS) is the proxy service that maintains the connections between the Experiment Session and devices. The connection between the Experiment Session and the Device Proxy Server is a TCP connection (Telnet Application.). And the connection between the Device Proxy Server and the device is a physical connection from the serial port of the DPS machine to the console port of the device.

The Database (DB) is used to maintain user, experiment, resource and system information.