Quality of Service
QoS Features and Components
Cisco 220 Series Smart Switches Administration Guide Release 1.1.0.x 249
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function of the traffic class to which they belong. See Configuring QoS
Queues.
• Other Traffic Class-Handling Attribute—Applies QoS functions to various
classes, including bandwidth management.
The QoS mode that is selected applies to all interfaces on the switch. The switch
supports the following QoS modes:
• Basic Mode—Class of service (CoS).
All traffic of the same class receives the same treatment, which is the single
QoS action of determining the egress queue on the egress port, based on
the indicated QoS value in the incoming frame. When operating in QoS
basic mode, the switch trusts this external assigned QoS value. The
external assigned QoS value of a packet determines its traffic class and
QoS.
• Advanced Mode—Per-flow quality of service (QoS).
In QoS advanced mode, a per-flow QoS consists of a class map and a
policer:
- A class map defines the kind of traffic in a flow, and contains one or more
ACLs. Packets that match the ACLs belong to the flow.
- A policer applies the configured QoS to a flow. The QoS configuration of
a flow may consist of egress queue, the DSCP or CoS/802.1p value, and
actions on out of profile (excess) traffic.
• Disable Mode—All traffic is mapped to a single best effort queue so that no
type of traffic is prioritized over another.
NOTE Only a single mode can be active at a time. When the switch is configured to work
in QoS advanced mode, the settings for QoS basic mode are not active and vice
versa.
When the QoS mode is changed, the following occurs:
• When changing from QoS advanced mode to any other mode, policy profile
definitions and class maps are deleted. ACLs bonded directly to interfaces
remain bonded.
• When changing from QoS basic mode to QoS advanced mode, the QoS
trust mode configuration in QoS basic mode is not retained.
• When disabling QoS, the shaper and queue setting (WRR/SP bandwidth
setting) are reset to default values.
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