H3C Technologies H3C S12500 Series Switches - Manual (Page 37)

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Applying the QoS policy globally
You can apply a QoS policy globally to the inbound or outbound direction of all ports.
To apply the QoS policy globally:
Step Command
1. Enter system view. system-view
2. Apply the QoS policy globally. qos apply policy policy-name global { inbound | outbound }
NOTE:
If the hardware resources of an interface card are insufficient, applying a QoS policy globally will fail on
the interface card. The system does not automatically roll back the QoS policy configuration already
applied to the main processing unit or other interface cards. To ensure consistency, you must use the undo
qos apply policy global command to manually remove the QoS policy configuration applied to them.
Applying the QoS policy to the control plane
When you apply the QoS policy to the control plane, follow these restrictions and guidelines:
• You can apply a QoS policy to the control plane of only an Ethernet interface card.
• By default, the switch is 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.
• When you apply a QoS policy to the control plane of the slot where the IRF port resides, if a class
in the QoS policy uses an Ethernet frame header ACL configured with rule permit to match all
packets, do not configure car cir or filter deny in the behavior associated with the class. Otherwise,
the IRF might split, and the switch cannot work correctly.
The packets entering a device can be processed by the data plane or the control plane.
• The units at the data plane are responsible for receiving, transmitting, and switching (forwarding)
packets, such as various dedicated forwarding chips. They deliver super processing speeds and
throughput.
• The units at the control plane are processing units running most routing and switching protocols and
responsible for protocol packet resolution and calculation, such as CPUs. Compared with data
plane units, they 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 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, ensuring that the control plane can receive, transmit, and
process packets properly.
To apply the QoS policy to the control plane: