Many such commercial and public-domain projects. MQP motivated by the fact that oddities do occur on a network. Create rules for different types of traffic. Maintain statistics on each rule for presentation. Be able to dump explained or unexplained packets.
Unexplained packets can lead to more rules to further classify the traffic.
Limited to a particular network segment. However as exponential growth occured in the Internet this approach was no longer satisfactory. Older networks provided network management as part of the link level using special control packets sent by a network manager. Allowed for control of switches even if problems existed at higher layers. However the Internet does not have a single link level and thus a more general method is needed and has been adopted.