3Com S7906E Configuration Manual page 1738

Applying the QoS policy globally
You can apply a QoS policy globally to the inbound or outbound direction of all ports.
Follow these steps to apply the QoS policy globally:
To do...
Enter system view
Apply the QoS policy globally
A QoS policy containing any of the nest, remark customer-vlan-id, and remark service-vlan-id
Actions cannot be applied globally.
Applying the QoS policy to the control plane
Packet processing units fit into the data plane and the control plane depending on their functions.
At the data plane are units responsible for receiving, transmitting, and switching (that is, forwarding)
packets, such as various dedicated forwarding chips. They deliver super processing speeds and
throughput.
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 legitimate packets correctly or timely. As a result, protocol performance is affected.
To address this problem, you can apply a QoS policy to the control plane to take QoS actions such as
traffic filtering or rate limiting on inbound traffic, thus ensuring that the control plane can receive,
transmit, and process packets normally.
Follow these steps to apply the QoS policy to the control plane:
To do...
Enter system view
Enter control plane view (on a
distributed device)
Enter control plane view (on a
distributed IRF device)
Apply the QoS policy to the
control plane
Use the command...
system-view
qos apply policy policy-name
global { inbound | outbound }
Use the command...
system-view
control-plane slot slot-number
control-plane chassis chassis-number
slot slot-number
qos apply policy policy-name
{ inbound | outbound }
2-8
Remarks
—
Required
Remarks
—
Required
Required
Required