Mapping Tables - Cisco Catalyst 3750 Software Configuration Manual

Chapter 26 Configuring QoS
Figure 26-4 Ingress, Single-Rate Policing and Marking Flowchart
Check if the packet is in
profile by querying the policer.

Mapping Tables

During QoS ingress processing, the switch represents the priority of all traffic (including non-IP traffic)
with an QoS label based on the DSCP or CoS value from the classification stage:
•
•
78-15870-01
Start
Get the clasification
result for the packet.
Is a policer configured
for this packet?
Yes
Yes
Pass
through
Check out-of-profile action
configured for this policer.
Modify DSCP according to the
policed-DSCP map. Generate
Done
During ingress classification, QoS uses configurable mapping tables to derive a corresponding
DSCP or CoS value from a received CoS, DSCP, or IP precedence value. These maps include the
CoS-to-DSCP map and the IP-precedence-to-DSCP map. You configure these maps by using the mls
qos map cos-dscp and the mls qos map ip-prec-dscp global configuration commands.
On an ingress port configured in the DSCP-trusted state, if the DSCP values are different between
the QoS domains, you can apply the configurable DSCP-to-DSCP-mutation map to the port that is
on the boundary between the two QoS domains. You configure this map by using the mls qos map
dscp-mutation global configuration command.
During ingress policing, QoS can assign another DSCP value to an IP or a non-IP packet (if the
packet is out of profile and the policer specifies a marked-down value). This configurable map is
called the policed-DSCP map. You configure this map by using the mls qos map policed-dscp
global configuration command.
No
No
Drop
Mark
a new QoS label.
Catalyst 3750 Metro Switch Software Configuration Guide
Understanding QoS
Drop packet.
26-11