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Catalyst 3560 Switch Command Reference
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Chapter 2 Catalyst 3560 Switch Cisco IOS Commands
mls qos rewrite ip dscp
mls qos rewrite ip dscp
Use the mls qos rewrite ip dscp global configuration command to configure the switch to change
(rewrite) the Differentiated Services Code Point (DSCP) field of an incoming IP packet. Use the no form
of this command to configure the switch to not modify (rewrite) the DSCP field of the packet and to
enable DSCP transparency.
mls qos rewrite ip dscp
no mls qos rewrite ip dscp
Syntax Description This command has no arguments or keywords.
Defaults DSCP transparency is disabled. The switch changes the DSCP field of the incoming IP packet.
Command Modes Global configuration
Command History
Usage Guidelines DSCP transparency affects only the DSCP field of a packet at the egress. If DSCP transparency is
enabled by using the no mls qos rewrite ip dscp command, the switch does not modify the DSCP field
in the incoming packet, and the DSCP field in the outgoing packet is the same as that in the incoming
packet.
Note Enabling DSCP transparency does not affect the port trust settings on IEEE 802.1Q tunneling ports.
By default, DSCP transparency is disabled. The switch modifies the DSCP field in an incoming packet,
and the DSCP field in the outgoing packet is based on the quality of service (QoS) configuration,
including the port trust setting, policing and marking, and the DSCP-to-DSCP mutation map.
Regardless of the DSCP transparency configuration, the switch modifies the internal DSCP value of the
packet that the switch uses to generate a class of service (CoS) value representing the priority of the
traffic. The switch also uses the internal DSCP value to select an egress queue and threshold.
For example, if QoS is enabled and an incoming packet has a DSCP value of 32, the switch might modify
the internal DSCP value based on the policy-map configuration and change the internal DSCP value
to 16. If DSCP transparency is enabled, the outgoing DSCP value is 32 (same as the incoming value). If
DSCP transparency is disabled, the outgoing DSCP value is 16 because it is based on the internal DSCP
value.
Release Modification
12.2(25)SE This command was introduced.
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