Quality of Service
QoS Basic Mode
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• CoS/802.1p—Traffic is mapped to queues based on the VPT field in the 
VLAN tag, or based on the per-port default CoS/802.1p value (if there is no 
VLAN tag on the incoming packet), the actual mapping of the VPT to queue 
can be configured in the mapping CoS/802.1p to Queue page.
• DSCP—All IP traffic is mapped to queues based on the DSCP field in the IP 
header. The actual mapping of the DSCP to queue can be configured in the 
DSCP to Queue page. If traffic is not IP traffic, it is mapped to the best effort 
queue.
• CoS/802.1p-DSCP—Either CoS/802.1p or DSCP whichever has been set.
STEP  3 Select Override Ingress DSCP to override the original DSCP values in the 
incoming packets with the new values according to the DSCP Override Table. 
When Override Ingress DSCP is enabled, the device uses the new DSCP values 
for egress queueing. It also replaces the original DSCP values in the packets with 
the new DSCP values. 
NOTE The frame is mapped to an egress queue using the new, rewritten 
value, and not by the original DSCP value. 
STEP  4 If Override Ingress DSCP was enabled, click DSCP Override Table to 
reconfigure DSCP.
DSCP In displays the DSCP value of the incoming packet that needs to be re-
marked to an alternative value.
STEP  5 Select the DSCP Out value to indicate the outgoing value is mapped.
STEP  6 Click Apply. The Running Configuration file is updated with the new DSCP values.
Interface QoS Settings
The Interface Settings page enables configuring QoS on each port of the device, 
as follows:
QoS State Disabled on an Interface—All inbound traffic on the port is 
mapped to the best effort queue and no classification/prioritization takes 
place.
QoS State of the Port is Enabled—Port prioritize traffic on ingress is 
based on the system wide configured trusted mode, which is either CoS/
802.1p trusted mode or DSCP trusted mode.