4000 Router Series ACL and QoS Configuration Guide

Rate limit also uses token buckets for traffic control. When rate limit is configured on an interface, a token

bucket handles all packets to be sent through the interface for rate limiting. If enough tokens are in the

token bucket, packets can be forwarded. Otherwise, packets are put into QoS queues for congestion

management. In this way, the traffic passing the physical interface is controlled.

Figure 10 Rate limit implementation

The token bucket mechanism limits traffic rate when accommodating bursts. It allows bursty traffic to be

transmitted if enough tokens are available. If tokens are scarce, packets cannot be transmitted until

efficient tokens are generated in the token bucket. It restricts the traffic rate to the rate for generating

tokens.

Rate limit controls the total rate of all packets on a physical interface. It is easier to use than traffic policing

in controlling the total traffic rate on a physical interface.

Configuring traffic policing

You can configure traffic policing by using the MQC approach or non-MQC approach. If traffic policing

is configured by using both the MQC approach and non-MQC approach, the configuration in MQC

approach takes effect.

Configuring traffic policing by using the MQC approach

Ste

Command

Remarks

1. Enter system view.

system-view N/A

2. Create a traffic class

and enter traffic class

view.

traffic classifier classifier-name

[ operator { and | or } ]

By default, no traffic class is

configured.

3. Configure match

criteria.

if-match [ not ] match-criteria

By default, no match criterion is

configured.

For more information about the

if-match command, see ACL and QoS

Command Reference.

4. Return to system view.

quit N/A