Cisco Systems 2960 manual 29-6

29-6
Catalyst 2960 Switch SoftwareConfiguration Guide
78-16881-01
Chapter29 Co nfiguring QoS
Understanding QoS
After classification, the packet is sent to the policing, marking, and the ingress queueing a nd scheduling
stages.
Figure29-3 Classification Flowchart
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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.
Assign default
port CoS.
Yes
Yes
No
No
No
Yes No
(Optional) Modify the
DSCP by using the
DSCP-to-DSCP-mutation
map. Use the DSCP
value to generate
the QoS label.
Read ingress interface
configuration for classification.
Assign DSCP identical
to DSCP in packet.
Check if packet came
with CoS label (tag).
Use the CoS value to
generate the QoS label.
Generate DSCP from
CoS-to-DSCP map.
Use the DSCP value to
generate the QoS label.
Yes
Read next ACL. Is there
a match with a "permit" action?
Assign the DSCP or CoS as specified
by ACL action to generate the QoS label.
Assign the default
DSCP (0).
Are there any (more) QoS ACLs
configured for this interface?
Check if packet came
with CoS label (tag).
Use CoS
from frame.
Start
Trust CoS (IP and non-IP traffic).
IP and
non-IP
traffic Trust DSCP or
IP precedence
(non-IP traffic).
Trust IP
precedence
(IP traffic).
Trust DSCP (IP traffic).
DoneDone
Done
Done
Assign the default port
CoS and generate a
DSCP from the
CoS-to-DSCP map.
Generate the DSCP by using
the CoS-to-DSCP map.