Content

| 8.4 |  | Policing and Marking |
| 8.4.5 |  | Classification and policing using Committed Access Rate (CAR) |

CAR is a multifaceted feature that implements both classification services and policing through rate limiting. This section describes its classification capability.

The classification services of CAR allow traffic flow limits to be placed on incoming traffic. These limits specify the average rate,

rate-bps, and the burst rate, burst-byte, that is permissible. Traffic that is nonconforming either because it exceeds the average rate or the burst rate specified can be marked down in terms of DSCP. As traffic flows through the network, networking devices can use the adjusted DSCP to determine how the traffic should be treated. For example, congestion management and avoidance techniques can be used to selectively drop packets from traffic that was previously marked down in terms of DSCP.

The policy-map command that enables CAR is

police and is specified for a given class of traffic. The exceed-action command determines whether the action should be to strictly enforce the policy by dropping the nonconforming packets, drop, or merely classify them by reducing the DSCP of non conforming packets and forward them policed-dscp-transmit.