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30-11
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
78-17058-01
Chapter 30 Configuring QoS
Understanding QoS
To communicate an ACL classification to an output policy, you assign a QoS number to specify packets
at ingress. This example identifies specific packets as part of QoS group 1 for later processing in an
output policy:
Switch(config)# policy-map in-gold-policy
Switch(config-pmap)# class in-class1
Switch(config-pmap-c)# set qos-group 1
Switch(config-cmap-c)# exit
Switch(config-cmap)# exit
You use the set qos-group command only in an input policy. The assigned QoS group identification is
subsequently used in an output policy with no mark or change to the packet. You use the match
qos-group in the output policy.
Note You cannot configure match qos-group for an input policy map.
This example creates an output policy to match the QoS group created in the input policy map
in-gold-policy. Traffic internally tagged as qos-group 1 is identified and processed by the output policy.
Switch(config)# class-map out-class1
Switch(config-cmap)# match qos-group 1
Switch(config-cmap)# exit
The switch supports a maximum of 16 QoS groups.
Table Maps
You can use table maps to manage a large number of traffic flows with a single command. You can
specify table maps in set commands and use them as mark-down mapping for the policers. You can also
use table maps to map an incoming QoS marking to a replacement marking without having to configure
a large number of explicit matches and sets. Table maps are used only in input policy maps.
Table maps can be used to:
• correlate specific CoS, DSCP, or IP precedence values to specific CoS, DSCP, or IP precedence
values
• mark down a CoS, DSCP, or IP precedence value
• assign defaults for unmapped values
A table map includes one of these default actions:
• default default-value—applies a specific default value (0 to 63) for all unmapped values
• default copy—maps all unmapped values to the equivalent value in another qualifier
• default ignore—makes no changes for unmapped values
This example creates a table to map specific CoS values to DSCP values. The default command maps all
unmapped CoS values to a DSCP value of 63.
Switch(config)# table-map cos-dscp-tablemap
Switch(config-tablemap)# map from 5 to 46
Switch(config-tablemap)# map from 6 to 56
Switch(config-tablemap)# map from 7 to 57
Switch(config-tablemap)# default 63
Switch(config-tablemap)# exit