NCT-1000/NCT-1020 User Guide
47
YML836 Rev2
Broadcast Storm Control
Broadcast storms may break down your network traffic. To avoid the broadcast storms from blocking your
network traffic, you can configure this field by choosing any option among 5% to 25%.
When broadcast storms are discovered, the broadcast storm packets can be filtered by percentage. For
example, the option 10% is selected. It means 10% of the broadcast storm packets will be allowed for the
network while the rest (90%) will be dropped. This allows the device to receive the broadcast storm packets
and simultaneously process other packets sent by different hosts.
To disable broadcast storm control, choose Off and click Set to apply the setting.
Priority Queue Service
Note:
The QoS function works under tagged based VLAN mode. Also note, ASTU supports
private VLAN or private/tagged VLAN simultaneously. AAT24A supports either private or
tagged VLAN. Please DO NOT switch the VLAN mode while the ASTU card is connected.
That will cause an unpredictable operational problem.
QoS Mode:
The QoS mode configures the sequence of the packets to be transmitted.
There are two priority queues – high and low. Queue is the packet pool that
collects or holds the packets to be transmitted. Each packet is assigned with
a priority queen (options 1 to 7). The QOS specifies the sequence to process
these waiting packets. There are three QoS modes:
First Come First Service:
The sequence of packets sent depends on the arriving order.
All High Before Low:
The packets in the high priority queue are always sent before those in the low
priority queue.
Weighted Round Robin:
(WRR) Options (1-7) represent the number of the high priority packets sent
before the low priority packets. Use the following diagram for example, option
5 is chosen in the WRR High Priority field, and option 2 is chosen in the WRR
Low Priority field. Then, in the high queue, five Packets “A, B, C, D, E” are
sent prior to the packets in the low queue. After the five packets are sent, two
packets “A and B” will be sent. The rest of the packets are processed in the
same way.
WRR High Priority Weight:
This field only works when Weighted Round Robin is selected from the QoS
Mode field.
WRR Low Priority Weight:
This field only works when Weighted Round Robin is selected from the QoS
Mode field.
Note:
For more details about vlan, refer to section 5.1.3. The QoS is only configurable in the
tagged vlan.
8021P Priority QoS High Priority Queue mapping
The selected 0~7 numbers will be mapped to high priority. Multiple numbers can be chosen. If a packet is
received with the priority queue, it will be processed by mapping to the priority queue table. For example,
numbers 0, 4, 5, 6, are chosen in this field. If the packet was already given the priority queue, 0, and it will
be sent to the high priority queue because number 0 is in the selected priority queue table. If the packet’s
priority is 2, then it will be forwarded to the low priority queue because the number 2 is not in the table.
Summary of Contents for NCT-1000
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