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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter35 Configuring QoS
Understanding QoS
When configuring policing on an SVI, you can create and configure a hierarchical policy map with these
two levels:
VLAN level—Create this primary level by configuring class maps and classes that specify the port
trust state or set a new DSCP or IP precedence value in the packet. The VLAN-level policy map
applies only to the VLAN in an SVI and does not support policers.
Interface level—Create this secondary level by configuring class maps and classes that specify the
individual policers on physical ports the belong to the SVI. The interface-level policy map only
supports individual policers and does not support aggregate policers. You can configure different
interface-level policy maps for each class defined in the VLAN-level policy map.
See the “Classifying, Policing, and Marking Traffic on SVIs by Using Hierarchical Policy Maps” section
on page 35-57 for an example of a hierarchical policy map.
Figure 35-5 shows the policing and marking process when hierarchical policy maps on an SVI.
Figure35-5 Policing and Marking Flowchart on SVIs
92355
Yes
Yes
No
No
Pass
through Drop
Mark
Get the VLAN and
interface-level classification
results for the packet.
Is an interface-level policer
configured for this packet?
Verify if the packet is in the
profile by querying the policer.
Verify the out-of-profile action
configured for this policer. Drop packet.
Modify DSCP according to the
policed-DSCP map. Generate
a new QoS label.
Start
Done