Operation Manual – QoS-QoS Profile
H3C S3100 Series Ethernet Switches
Chapter 1 QoS Configuration
1-12
III. Traffic policing
The typical application of traffic policing is to supervise specific traffic into the network
and limit it to a reasonable range, or to "discipline" the extra traffic. In this way, the
network resources and the interests of the operators are protected. For example, you
can limit HTTP packets to be within 50% of the network bandwidth. If the traffic of a
certain connection is excess, traffic policing can choose to drop the packets or to reset
the priority of the packets.
Traffic policing is widely used in policing the traffic into the network of internet service
providers (ISPs). Traffic policing can identify the policed traffic and perform pre-defined
policing actions based on different evaluation results. These actions include:
z
Discarding the nonconforming packets.
z
Forwarding the conforming packets or nonconforming packets.
z
Marking the conforming packets with 802.1p precedence and then forwarding the
packets.
z
Marking the conforming packets or nonconforming packets with DSCP
precedence and forwarding the packets.
IV. Traffic shaping
Traffic shaping is a measure to regulate the output rate of traffic actively. Its typical
application is to control local traffic output based on the traffic policing indexes of
downstream network nodes.
The major difference between traffic shaping and traffic policing is that the packets to
be dropped in traffic policing are cached in traffic shaping——usually in buffers or
queues, as shown in
Figure 1-6
. When there are enough tokens in the token bucket,
the cached packets are sent out evenly. Another difference between traffic policing and
traffic shaping is that traffic shaping may increase the delay while traffic policing hardly
increases the delay.
