Cisco 500 Series - Mapping Dscp to Queue

Quality of Service
Configuring QoS - General
607 Cisco 500 Series Stackable Managed Switch Administration Guide
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• Output Queue—Select the egress queue to which the 802.1p priority is
mapped. Either four or eight egress queues are supported, where Queue 4
or Queue 8 is the highest priority egress queue and Queue1 is the lowest
priority.
STEP 3 For each 802.1p priority, select the Output Queue to which it is mapped.
STEP 4 Click Apply, Cancel or Restore Defaults. 801.1p priority values to queues are
mapped, and the Running Configuration file is updated, the changes that were
entered are cancelled, or previously defined values are restored.
Mapping DSCP to Queue
The DSCP (IP Differentiated Services Code Point) to Queue page maps DSCP
values to egress queues. The DSCP to Queue Table determines the egress
queues of the incoming IP packets based on their DSCP values. The original VPT
(VLAN Priority Tag) of the packet is unchanged.
By simply changing the DSCP to Queue mapping and the Queue schedule method
and bandwidth allocation, it is possible to achieve the desired quality of services
in a network.
The DSCP to Queue mapping is applicable to IP packets if:
• The device is in QoS Basic mode and DSCP is the trusted mode, or
• The device is in QoS Advanced mode and the packets belongs to flows that
is DSCP trusted
Non-IP packets are always classified to the best-effort queue.