Implementations
On Cisco equipment, both traffic policing and shaping are implemented through the token bucket algorithm.
Traffic policing in ATM networks is known as Usage Parameter Control (UPC) and Network Parameter Control (NPC). The network can also discard non-conformant traffic in the network (using Priority Control). The reference for both traffic policing and traffic shaping in ATM (given by the ATM Forum and the ITU-T) is the Generic Cell Rate Algorithm (GCRA), which is described as a version of the leaky bucket algorithm.
Traffic policing requires maintenance of numerical statistics and measures for each policed traffic flow, but it does not require implementation or management of significant volumes of packet buffer. Consequently it is significantly less complex to implement than traffic shaping.
Read more about this topic: Traffic Policing