Chapter 1 Port Qos Configuration - Zte ZXR10 5900E Series Configuration Manual

This mode ensures that each queue has a chance to be scheduled. The weight
of each queue is different, so the time of each queue to be scheduled is different.
The weight refers to the proportion of resources obtained by each queue. The
packets in a queue with a higher priority take precedence over that in a queue
with a lower priority.
Deficit Weighted Round Robin (DWRR)
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This mode also ensures that each queue has a chance to be scheduled. The
weight of each queue is also different from another queue. The difference
between DWRR and WRR is: The weight configured in DWRR indicates the
scheduled bytes of eight queues during each scheduling (unit: kbyte), and the
weight configured in WRR indicates the number of scheduled packets of each
queue during each scheduling. So, the size of DWRR packets has less influence
on the bandwidth.
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Default priority
When packet congestion occurs, the switch will discard packets selectively.
general, this selective rule refers to the drop priority. Each packet to the port from the
egress will be colored in accordance with its carried 802.1p label (packet priority).
Packets with different priorities will be colored green (low), yellow (middle), or red
(high) in accordance with a certain mapping relationship. Packets are dropped in
accordance with the color when queue congestion occurs. The color can also be
used by other drop policies.
The mapping table between the 802.1P user priority and the local drop priority of a
switch must be set.
When a switch receives a packet, it determines the CoS value of the packet. For a
TAG packet, the CoS value refers to the 802.1P user priority in the packet. For a
non-TAG packet, the switch determines the local priority of a packet in accordance
with the default local priority of the receiving port, and then determines the CoS value
of the packet in accordance with the relationship between the local priority and the
CoS value. After that, the mapping table determines the drop priority of the packet in
accordance with the CoS value. The default value is 0.
The drop priority is configured on the ingress interface.
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Local priority
The local priority here is different from the common "internal priority" used in the ACL
rule. The local priority here is a mapping relationship between the 802.1p packet and
eight CoS queues of the egress. That is to say, 802.1p packets with different priorities
(level 0-7) will be sent to different CoS queues for scheduling.
The local priority mapping is configured on the ingress.
The local mapping relationship is valid only for the local switching chip. It becomes
invalid when the ingress used for the mapping configuration and the egress used for
the scheduling are not in the same board or the same switching chip.
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Tail Drop
SJ-20150114102049-008|2015-01-15 (R1.0)

Chapter 1 Port QoS Configuration

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