Introduction to Rate Limiting, Rate Shaping, and Scheduling

The terms rate limiting and rate shaping are used throughout this chapter to describe QoS (Quality of Service) features. Some QoS features perform both rate limiting and rate shaping. Rate limiting is the process of restricting traffic to a peak rate (PR). Rate shaping is the process of reshaping traffic throughput to give preference to higher priority traffic or to buffer traffic until forwarding resources become available.

Both rate limiting and rate shaping allow you to take action on traffic that exceeds the configured limits. These actions include forwarding traffic, dropping traffic, and marking the excess traffic for possible drops later in the communication path. Software counters allow you to record traffic statistics such as total packets forwarded and total packets dropped.