With a traffic policer such as class-based policing, what do Committed Burst (BC) and Excess Burst (Be) mean and how should I select these values?
A. A traffic policer does not buffer excess packets and transmit them later, as is the case for a shaper. Instead, the policer executes a simple send or do not send policy without buffering. During periods of congestion, since you cannot buffer, the best you can do is drop packets less aggressively by properly configuring extended burst. Therefore, it is important to understand the policer uses the normal burst and extended burst values to ensure the configured Committed Information Rate (CIR) is reached. The burst parameters are loosely modeled on the generic buffering rule for routers. The rule recommends configuring buffering equal to the round-trip time bitrate to accommodate the outstanding Transmission Control Protocol (TCP) windows of all connections in times of congestion. The following table describes the purpose and the recommended formula for the normal and extended burst values: Burst Parameter Purpose Recommended Formula normal burst • Implements a standard token bucket. •
Related Questions
- With a traffic policer such as class-based policing, what do Committed Burst (BC) and Excess Burst (Be) mean and how should I select these values?
- What values should I select for Committed Information Rate (CIR), Committed Burst (BC), Excess Burst (Be), and Minimum CIR (MinCIR)?
- Is the Committed Access Rate (CAR) feature used for traffic policing on the Cisco 7200 series with ATM?
