by Alisha Cecil. Numerous tools are available to help administrators with the monitoring and analysis of network traffic. This paper discusses router based monitoring techniques and non-router based monitoring techniques (passive versus active). It gives an overview of the three most widely used router based network monitoring tools available (SNMP, RMON, and Cisco Netflow), and provides information about two newer monitoring methods that use a combination of passive and active monitoring techniques (WREN and SCNM).