Cisco Catalyst 2975 Software Configuration Manual page 731

Chapter 33 Configuring QoS
Figure 33-3 Classification Flowchart
configuration for classification.
IP and
non-IP
traffic
Check if packet came
with CoS label (tag).
Yes
Use CoS Assign default
from frame. port CoS.
Generate DSCP from
CoS-to-DSCP map.
Use the DSCP value to
generate the QoS label.
Done
Are there any (more) QoS ACLs
configured for this interface?
Yes
Read next ACL. Is there
a match with a "permit" action?
Yes
Assign the DSCP or CoS as specified
by ACL action to generate the QoS label.
OL-19720-02
Start
Read ingress interface
Trust DSCP or Trust IP
IP precedence precedence
(non-IP traffic). (IP traffic).
No
Generate the DSCP based on
IP precedence in packet. Use
the IP-precedence-to-DSCP
map. Use the DSCP value to
generate the QoS label.
No
No
Assign the default
DSCP (0).
Done
Trust CoS (IP and non-IP traffic).
Trust DSCP (IP traffic).
Assign DSCP identical
to DSCP in packet.
(Optional) Modify the
DSCP by using the
DSCP-to-DSCP-mutation
map. Use the DSCP
value to generate
the QoS label.
Done
Check if packet came
with CoS label (tag).
Yes
Use the CoS value to
generate the QoS label.
Generate the DSCP by using
the CoS-to-DSCP map.
Catalyst 2975 Switch Software Configuration Guide
Understanding QoS
No
Assign the default port
CoS and generate a
DSCP from the
CoS-to-DSCP map.
Done
33-7