One function is rate-limiting, or setting a ceiling on the amount of bandwidth that can be consumed by a particular application, user, port, network interface, or some other resource. The rate-limiting component of Policer is a bandwidth management tool that enables Service Providers to set up and enforce policies about traffic flows. With rate limiting, network operators dictate a maximum amount of bandwidth that a particular resource can consume. Then, network operators can configure Policer with several levels of policy that dictate what action should be taken on traffic that exceeds that limit. Any traffic generated by that same resource that exceeds 100 Kbps could drop to a lower priority class or be discarded altogether.
Customers pay different fees based on the amount of bandwidth they use.
Service Providers can limit traffic based on network interface at Internet peering points, where traffic from many Service Providers is exchanged. If one operator feels it is carrying too much of a load for another operator, rate-limiting is one way to balance the traffic patterns. Diff-Serv requires a policing component such as Policer. Network operators can define up to eight classes of service. Setting up these types policies using packet classification and rate-limiting is automated using the Policer mechanism.