A system for generating hints on network construction exercises for beginners

When performing network construction exercises, a number of beginners fail to satisfy the requirements for the network reachability of communication data. In helping these learners, instructors explain the errors in the behavior of the learners' networks; such errors are referred to as behavior errors. Because of limitations on the number of network devices, traditional exercises have tended to divide the learners into several groups, each of which then constructs the required networks. In recent years, however, it has become possible for each learner to implement networks using an interconnection of virtual machines running on an ordinary personal computer. This phenomenon has increased the time that learners must wait to receive help from an instructor, because the number of instructors is far fewer than the number of learners. Hence, we have developed a hint generation system that displays information regarding behavior errors as hints. The system receives a learner's network settings and an exercise problem as input, and computes the behavior of both the learner's network and the correct network. An analysis of both behaviors allows the system to specify the behavior errors and display static images of the behavior of both networks in parallel and messages describing the errors.