Cisco WS-C3550-12G Software Configuration Manual page 486

Configuring QoS
Command
Step 6 trust [cos | dscp | ip-precedence]
Step 7 set {ip dscp new-dscp | ip precedence
new-precedence}
Catalyst 3550 Multilayer Switch Software Configuration Guide
20-34
Purpose
Configure the trust state, which selects the value that QoS uses as the
source of the internal DSCP value.
Note This command is mutually exclusive with the set command
within the same policy map. If you enter the trust command,
then skip Step 7.
By default, the port is not trusted. If no keyword is specified when the
command is entered, the default is dscp.
The keywords have these meanings:
• cos—QoS derives the internal DSCP value by using the received
or default port CoS value and the CoS-to-DSCP map.
• dscp—QoS derives the internal DSCP value by using the DSCP
value from the ingress packet. For non-IP packets that are tagged,
QoS derives the internal DSCP value by using the received CoS
value; for non-IP packets that are untagged, QoS derives the
internal DSCP value by using the default port CoS value. In either
case, the internal DSCP value is derived from the CoS-to-DSCP
map.
• ip-precedence—QoS derives the internal DSCP value by using the
IP precedence value from the ingress packet and the
IP-precedence-to-DSCP map. For non-IP packets that are tagged,
QoS derives the internal DSCP value by using the received CoS
value; for non-IP packets that are untagged, QoS derives the
internal DSCP value by using the default port CoS value. In either
case, the internal DSCP value is derived from the CoS-to-DSCP
map.
For more information, see the
section on page 20-39.
Classify IP traffic by setting a new value in the packet.
For ip dscp new-dscp, enter a new DSCP value to be assigned to
•
the classified traffic. The range is 0 to 63.
For ip precedence new-precedence, enter a new IP-precedence
•
value to be assigned to the classified traffic. The range is 0 to 7.
Chapter 20
"Configuring the CoS-to-DSCP Map"
Configuring QoS
78-11194-03