H3C Technologies H3C S10500 Series Switches - Manual (Page 31)

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• The control plane has processing units running most routing and switching protocols and
responsible for protocol packet resolution and calculation, such as CPUs. Compared with data
plane units, the control plane units allow for great packet processing flexibility, but have lower
throughput.
When the data plane receives packets that it cannot recognize or process, it transmits them to the control
plane. If the transmission rate exceeds the processing capability of the control plane, which very likely
occurs at times of DoS attacks, the control plane will be busy handling undesired packets and fail to
handle legitimate packets correctly or timely. As a result, protocol performance is affected.
To address this problem, apply a QoS policy to the control plane to take QoS actions, such as traffic
filtering or rate limiting, on inbound traffic. This action ensures that the control plane can receive, transmit,
and process packets properly.
Follow these steps to apply the QoS policy to the control plane:
To do… Use the command… Remarks
Enter system view system-view —
Enter control plane view (in standalone mode) control-plane slot slot-number Required
Enter control plane view (in IRF mode)
control-plane chassis chassis-number slot
slot-number
Required
Apply the QoS policy to the control plane qos apply policy policy-name inbound Required
CAUTION:
•
By default, devices are configured with pre-defined control plane policies, which take effect on the
control planes by default. A pre-defined control plane QoS policy uses the system-index to identify the
type of packets sent to the control plane. You can reference system-indexes in if-match commands in
class view for traffic classification and then re-configure traffic behaviors for these classes as required.
You can use the display qos policy control-plane pre-defined command to display them.
• In a QoS policy for control planes, if a system index classifier is configured, the associated traffic
behavior can contain only the car action or the combination of car and accounting packet actions. In
addition, if the CAR action is configured, only its CIR setting can be applied.
• In the QoS policy for a control plane, if a system index classifier is not configured, the associated traffic
behaviors also take effect on the data traffic of the card where the control plane resides.
• If you fail to apply a QoS policy to a control plane or fail to refresh the QoS policy applied to a control
plane because the hardware resources of the card are insufficient, you can use the undo qos apply
policy command to manually remove the QoS policy from the control plane.
Displaying and maintaining QoS policies
To do… Use the command… Remarks
Display traffic class configuration
display traffic classifier user-defined [ tcl-name ] [ |
{ begin | exclude | include } regular-expression ] Available in any
view
Display traffic behavior
configuration
display traffic behavior user-defined
[ behavior-name ] [ | { begin | exclude | include }
regular-expression ]
Available in any
view
Display user-defined QoS policy
configuration
display qos policy user-defined [ policy-name
[ classifier tcl-name ] ] [ | { begin | exclude |
include } regular-expression ]
Available in any
view