Cisco 350 Series Administration Manual page 649

Quality of Service
QoS Basic Mode
STEP 1
STEP 2
STEP 3
Cisco 350, 350X and 550X Series Managed Switches, Firmware Release 2.4, ver 0.4
Workflow to Configure Basic QoS Mode
To configure Basic QoS mode, perform the following:
1. Select Basic mode for the system by using the QoS Properties page.
2. Select the trust-behavior using the Global Setting page. The device supports CoS/802.1p
trusted mode and DSCP trusted mode. CoS/802.1p trusted mode uses the 802.1p priority in
the VLAN tag. DSCP trusted mode use the DSCP value in the IP header.
If there is any port that, as an exception, should not trust the incoming CoS mark, disable the
QoS state on that port using the Interface Settings page.
Enable or disable the global selected trusted mode at the ports by using the Interface Settings
page. If a port is disabled without trusted mode, all its ingress packets are forward in best
effort. It is recommended that you disable the trusted mode at the ports where the CoS/802.1p
and/or DSCP values in the incoming packets are not trustworthy. Otherwise, it might
negatively affect the performance of your network
Global Settings
The Global Settings page contains information for enabling Trust on the device (see the Trust
Mode field below). This configuration is active when the QoS mode is Basic mode. Packets
entering a QoS domain are classified at the edge of the QoS domain.
To define the Trust configuration:
Click Quality of Service > QoS Basic Mode > Global Settings.
Select the Trust Mode while the device is in Basic mode. If a packet CoS level and DSCP tag
are mapped to separate queues, the Trust mode determines the queue to which the packet is
assigned:
• 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.
Select Override Ingress DSCP to override the original DSCP values in the incoming packets
with the new values entered in the DSCP Override table. When Override Ingress DSCP is
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