Single-Rate Two-Color Policer Overview
Single-rate two color policing applies two types of rate limits on the traffic:
- Bandwidth—The number of bits per second permitted, on average.
- Maximum burst size—The maximum size permitted for bursts of data that exceed the given bandwidth limit.
The policer classifies traffic into two groups: traffic that conforms to the bandwidth limit or the peak burst size, and traffic that exceeds the bandwidth limit and the peak burst size. Each category is associated with an action. For conforming traffic (also called green traffic), the action is to transmit the packet. For nonconforming traffic (also called red traffic), the action might be to discard the packet or to first mark the packet with a higher drop priority and then transmit the packet. If congestion occurs downstream, the packets with higher loss priority are more likely to be discarded.
The following configuration demonstrates how the policer works in a sample scenario.
If traffic arriving on or exiting the interface exceeds 90 percent of the available bandwidth and exceeds the 300 KB burst-size limit, the packets are marked with a high loss priority. As the traffic rate slows and the newly arriving traffic conforms to the configured limits, Junos OS stops marking packets with the high loss priority.
