Control Plane Policing is a Quality of Service policy that is applide to traffic towards or from the routers control plane CPU.
Control Plane Policing Policies are used to limit known traffic to a given rate to protect the CPU from unexpected extreme rates of traffic that could impact the stability of the router.
CoPP policies usually only have an input policy that allow traffic to the control plane to be policed at a desired rate.
A properly planned Control Plane Policing Policy, network traffic is placed into various classes based on the type of traffic, such as management, routing protocols or known IP addresses. The CoPP policy is used to limit traffic to the control plane for each of these classes.
When a rate for a CoPP policy is being defined, the rate for a class may not be known without requiring further investigation. The quality of service police command can use confirm, exceed or violate actions that can be programmed to drop or transmit traffic. By choosing to transmit traffic that exceeds the policed rate and monitoring CoPP, the policy can be adjusted to meet requirements.