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Configuring Quality of Service 425
Basic QoS Mode
In basic QoS mode, it is possible to activate one of the Trust modes, including:
•VPT
• DSCP
•TCP
•UDP
•None
In addition, a single MAC-based or IP-based ACL can be attached directly to the interface (see
Configuring Network Security for more information). Only packets that have a
Forward
action are
assigned to the output queue, based on the specified classification.
By properly configuring the output queues, you can set the following basic mode services:
•
Minimum Delay
— The queue is assigned to a strict priority policy, and traffic is assigned to
the highest priority queue.
•
Best Effort
— Traffic is assigned to the lowest priority queue
•
Bandwidth Assignments
— By configuring the WRR scheduling scheme and choosing the
right weights, you can assign bandwidths.
Advanced QoS Mode
Advanced QoS mode provides rules for specifying flow classification and assigning rule actions that
relate to bandwidth management. The rules are defined in classification control lists (CCL).
CCLs are set according to the classification defined in the ACL, and they cannot be defined until a
valid ACL is defined. When CCLs are defined, you can group ACLs and CCLs together in a more
complex structure, called a "policy." Policies can be applied to an interface. Policy ACLs/CCLs are
applied in the sequence they appear within the policy. Only a single policy can be attached to a
port.
In advanced QoS mode, ACLs can be applied directly to an interface. However, a policy and ACL
cannot be simultaneously applied to an interface.
After assigning packets to a specific queue, you can apply services such as configuring output
queues for the scheduling scheme, or configuring output shaping for burst size, CIR, or CBS per
interface or per queue.
Configuration of Services - Examples
You can use advanced QoS mode settings to apply the following services to network traffic:
•
Best Effort
— Traffic is assigned to the lowest priority queue.
•
802.1p
— The VPT value is set according to the classification.
•
IP DSCP
— The value is set according to the classification.