The Switch TopN Reports utility allows you to collect and analyze data for each physical port on a switch in switcehs running Cat OS .When the Switch TopN Reports utility starts, it gathers data from the appropriate hardware counters, and then goes into sleep mode for a user-specified period. When the sleep time ends, the utility gathers the current data from the same hardware counters, compares the current data from the earlier data, and stores the difference. If you enter the show top command processing begins. This is available for the 4000 series switches also. Also, the Switch TopN Reports utility cannot be used to generate reports on Multilayer Switch Module (MSM) or Multilayer Switch Feature Card (MSFC) ports.
See the document:
http://www.cisco.com/en/US/products/hw/switches/ps663/products_configuration_guide_chapter09186a00800915c6.html
