4-3
z Dropping conforming or non-conforming packets.
z Marking a conforming packet or a non-conforming packet with a new DSCP precedence value and
forwarding the packet.
z Traffic Shaping
Traffic shaping provides measures to adjust the rate of outbound traffic actively. A typical traffic shaping
application is to limit the local traffic output rate according to the downstream traffic policing parameters.
The difference between traffic policing and GTS is that packets to be dropped in traffic policing are
cached in a buffer or queue in GTS, as shown in
　. When there are enough tokens in the token bucket,
these cached packets are sent at an even rate. Traffic shaping may result in an additional delay while
traffic policing does not.
z Diagram for GTS
For example, in
　, Switch A sends packets to Switch B. Switch B performs traffic policing on packets
from Switch A and drops packets exceeding the limit.
z GTS application
You can perform traffic shaping for the packets on the outgoing interface of Switch A to avoid
unnecessary packet loss. Packets exceeding the limit are cached in Switch A. Once resources are
released, traffic shaping takes out the cached packets and sends them out. In this way, all the traffic
sent to Switch B conforms to the traffic specification defined in Switch B.
Line Rate
The line rate of a physical interface specifies the maximum rate for forwarding packets (including critical
packets).
Line rate also uses token buckets for traffic control. With line rate configured on an interface, all packets
to be sent through the interface are first handled by the token bucket at line rate. If there are enough
tokens 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.
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