Applying a DSCP-to-traffic class mutation map to an interface

The following actions must be completed.

A QoS DSCP-to traffic class map must been configured.
For Extreme 8720, Extreme 8520, SLX 9250, and SLX 9150 devices, a Layer 2 switch port needs that the qos trust dscp be enabled before applying the qos dscp-to-traffic class map.

Similarly, on the Layer 2 switch port qos trust dscp cannot be disabled before removing the qos dscp-to-traffic class map.

Enter global configuration mode.
```
device# configure terminal
```

Enter interface configuration mode.

device(config)# interface ethernet 1/2

Activate the QoS DSCP-to-traffic class mutation map on the interface.
```
device(conf-if-eth-1/2)# qos dscp-traffic-class dscpTcMap  
```
Return to privileged EXEC mode.
```
device(conf-if-eth-1/2)# end
```

Verify the configuration

device# show qos maps dscp-traffic-class 

Dscp-to-Traffic-Class map 'dscpTcMap' 
{x/y: traffic-class = x, drop-precedence = y & dscp = d1d2}
d1 :  d2  0   1   2   3   4   5   6   7   8   9 
------------------------------------------------
0 :     0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 4/2 1/0
1 :     1/0 1/0 1/0 1/0 1/0 1/0 2/0 2/0 2/0 2/0
2 :     2/0 2/0 2/0 2/0 3/0 3/0 3/0 3/0 3/0 3/0
3 :     3/0 3/0 4/0 4/0 4/0 4/0 4/0 4/0 4/0 4/0
4 :     5/0 5/0 5/0 5/0 5/0 5/0 5/0 5/0 6/0 6/0
5 :     6/0 6/0 6/0 6/0 6/0 6/0 7/0 7/0 7/0 7/0
6 :     7/0 7/0 7/0 7/0

   Enabled on the following interfaces: Eth 1/2

Save the running-config file to the startup-config file.
```
device# copy running-config startup-config
```

Applying a QoS DSCP-to-traffic class map to an interface configuration example

device# configure terminal
device(config)# interface ethernet 1/2 
device(conf-if-eth-1/2)# qos dscp-traffic-class dscpTcMap  
device(conf-if-eth-1/2)# end
device# show qos maps dscp-traffic-class 
device# copy running-config startup-config