Remote Monitoring (RMON) is an Internet Engineering Task Force (IETF) standard monitoring specification that allows various network agents and console systems to exchange network monitoring data. The Supervisor Engine software provides embedded support for these components of the RMON specification.
The embedded RMON agent allows the switch to monitor network traffic from all ports simultaneously at the data-link layer of the OSI model without requiring a dedicated monitoring probe or network analyzer.
All switches by default support mini-RMON. This means you can get alarms, events, statistics, and history directly from the switches.
You need a Network Analysis Module (NAM) or a switch probe for full RMON functionality. There is no requirement to install a RMON license for switches and it is up to the user to use the honor system to install the license and to complete the legality to enable/use RMON features.