Configuring Cos Classification - Cisco Nexus 5000 Series Configuration Manual

Configuring QoS
Use the show class-map command to display the ACL class-map configuration:
switch# show class-map class_acl

Configuring CoS Classification

You can classify traffic based on the class of service (CoS) in the IEEE 802.1Q header. This 3-bit field is
defined in IEEE 802.1p to support QoS traffic classes. CoS is encoded in the high order 3 bits of the VLAN
ID Tag field and is referred to as user_priority.
If a system class is configured with a no-drop function, the match cos command serves an additional purpose.
The switch sends the CoS value to the adapter so that the adapter will apply a PFC pause for this CoS value.
The FCoE system class has a default CoS value of 3. You can add a match cos configuration to the FCoE
system class to set a different CoS value. A PFC pause will be applied to traffic that matches the new value.
SUMMARY STEPS
1. switch# configure terminal
2. switch(config)# class-map type qos class-name
3. switch(config-cmap-qos)# match cos cos-value
4. (Optional) switch(config-cmap-qos)# no match cos cos-value
DETAILED STEPS
Command or Action
Step 1 switch# configure terminal
Step 2 switch(config)# class-map type qos
class-name
Step 3 switch(config-cmap-qos)# match cos
cos-value
Step 4 switch(config-cmap-qos)# no match cos
cos-value
This example shows how to classify traffic by matching packets based on a defined CoS value:
switch# configure terminal
switch(config)# class-map type qos class_cos
switch(config-cmap-qos)# match cos 4, 5-6
Use the show class-map command to display the CoS value class-map configuration:
switch# show class-map class_cos
OL-20921-01
Purpose
Enters configuration mode.
Creates a named object that represents a class of traffic. Class-map names
can contain alphabetic, hyphen, or underscore characters, are case sensitive,
and can be up to 40 characters.
Specifies the CoS value to match for classifying packets into this class.
You can configure a CoS value in the range of 0 to 7.
When a Cisco Nexus 2148T Fabric Extender is connected and in
Note
use, data traffic should never be marked with a CoS value of 7.
CoS 7 is reserved for control traffic transiting the Fabric Extender.
(Optional)
Removes the match from the traffic class.
Cisco Nexus 5000 Series NX-OS Quality of Service Configuration Guide
Configuring Class Maps
17