Cisco Catalyst 3560-X Software Configuration Manual page 978

Configuring Standard QoS
A policy map can contain multiple class statements, each with different match criteria and actions.
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A separate policy-map class can exist for each type of traffic received on the SVI.
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In a switch stack, you cannot use the match input-interface class-map configuration command to
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specify interfaces across stack members in a policy-map class.
A policy-map and a port trust state can both run on a physical interface. The policy-map is applied before
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the port trust state.
• If you configure the IP-precedence-to-DSCP map by using the mls qos map ip-prec-dscp
dscp1...dscp8 global configuration command, the settings only affect packets on ingress interfaces
that are configured to trust the IP precedence value. In a policy map, if you set the packet IP
precedence value to a new value by using the set ip precedence new-precedence policy-map class
configuration command, the egress DSCP value is not affected by the IP-precedence-to-DSCP map.
If you want the egress DSCP value to be different than the ingress value, use the set dscp new-dscp
policy-map class configuration command.
• If you enter or have used the set ip dscp command, the switch changes this command to set dscp in
its configuration. If you enter the set ip dscp command, this setting appears as set dscp in the switch
configuration.
You can use the set ip precedence or the set precedence policy-map class configuration command
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to change the packet IP precedence value. This setting appears as set ip precedence in the switch
configuration.
If VLAN-based QoS is enabled, the hierarchical policy map supersedes the previously configured
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port-based policy map.
The hierarchical policy map is attached to the SVI and affects all traffic in the VLAN. The actions
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specified in the VLAN-level policy map affect the traffic belonging to the SVI. The police action on
the port-level policy map affects the ingress traffic on the affected physical interfaces.
• When configuring a hierarchical policy map on trunk ports, the VLAN ranges must not overlap. If
the ranges overlap, the actions specified in the policy map affect the incoming and outgoing traffic
on the overlapped VLANs.
Aggregate policers are not supported in hierarchical policy maps.
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When VLAN-based QoS is enabled, the switch supports VLAN-based features, such as the VLAN
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map.
You can configure a hierarchical policy map only on the primary VLAN of a private VLAN.
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When you enable VLAN-based QoS and configure a hierarchical policy map in a switch stack, these
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automatic actions occur when the stack configuration changes:
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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
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When a new stack master is selected, the stack master re-enables and reconfigures these features
on all applicable interfaces on the stack master.
When a stack member is added, the stack master re-enables and reconfigures these features on
all applicable ports on the stack member.
When you merge switch stacks, the new stack master re-enables and reconfigures these features
on the switches in the new stack.
When the switch stack divides into two or more switch stacks, the stack master in each switch
stack re-enables and reconfigures these features on all applicable interfaces on the stack
members, including the stack master.
Chapter 1 Configuring QoS
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