Why should QoS policing be implemented?

QoS policing should be implemented to adhere network traffic to a contracted committed information rate (CIR). As an example, if your enterprise contracted a Metro Ethernet connection with an access link of 1 Gb/s and a CIR of 400 Mb/s, you would need to make sure that traffic does not exceed the CIR except for occasional bursts. QoS policing is not used to police LAN applications. QoS policing is not used to police WAN applications. QoS will not help with maintaining a contracted burst rate.