HI ,

Besides delivering a real-time snapshot of bandwidth usage and consumption, the Cisco NAM Appliances also deliver a continuous historical view of how the bandwidth was used so you can quickly decide when and where to make changes in network resources including applying Cisco acceleration and control mechanisms.

You can create report for Network abndwidth usage by using following URL:

http://www.cisco.com/en/US/docs/net_mgmt/network_analysis_module_software/3.6/user/guide/report.html#wp1042434

Data can also be collected over a select period of time and then analyzed after the event to discover when an anomaly has occurred so it can be immediately resolved.

See fig 8 in the following URL:

http://www.cisco.com/en/US/prod/collateral/netmgtsw/ps5740/ps5688/ps10113/data_sheet_c78-506457.html

Sachin Garg