Cisco 500 series Administration Manual page 430

Configuring Quality of Service
QoS Advanced Mode
STEP 5
Cisco 500 Series Stackable Managed Switch Administration Guide
The frame is mapped to an egress queue using the new, rewritten
NOTE
value, and not by the original DSCP value.
If Override Ingress DSCP was enabled, click DSCP Override Table to
reconfigure DSCP. See the DSCP Override Table page for details.
Configuring Out-of-Profile DSCP Mapping
When a policer is assigned to a class maps (flows), you can specify the action to
take when the amount of traffic in the flow(s) exceeds the QoS-specified limits.
The portion of the traffic that causes the flow to exceed its QoS limit is referred to
as out-of-profile packets.
If the exceed action is Out of Profile DSCP, the switch remaps the original DSCP
value of the out-of-profile IP packets with a new value based on the Out of Profile
DSCP Mapping Table. The switch uses the new values to assign resources and the
egress queues to these packets. The switch also physically replaces the original
DSCP value in the out of profile packets with the new DSCP value.
To use the out-of-profile DSCP exceed action, remap the DSCP value in the Out Of
Profile DSCP Mapping Table. Otherwise the action is null, because the DSCP value
in the table remaps the packets to itself by factory default.
This feature changes the DSCP tags for incoming traffic switched between
trusted QoS domains. Changing the DSCP values used in one domain, sets the
priority of that type of traffic to the DSCP value used in the other domain to
identify the same type of traffic.
These settings are active when the system is in the QoS basic mode, and once
activated they are active globally.
For example: Assume that there are three levels of service: Silver, Gold, and
Platinum and the DSCP incoming values used to mark these levels are 10, 20, and
30 respectively. If this traffic is forwarded to another service provider that has the
same three levels of service, but uses DSCP values 16, 24, and 48, Out of Profile
DSCP Mapping changes the incoming values as they are mapped to the outgoing
values.
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