Traffic Shaping
When the rate of an interface on a downstream device is slower than that of an interface on an
upstream device or burst traffic occurs, traffic congestion may occur on the downstream device
interface. Traffic shaping can be configured on the interface of an upstream device so that
outgoing traffic is sent at even rates and congestion is avoided.
The AR500 supports traffic shaping adaptation and level-3 traffic shaping. Three-level shapers
include the flow queue shaper, subscriber queue shaper, and port queue shaper.
Congestion Management
If a network transmitting both delay-sensitive and delay-insensitive services is congested
intermittently, congestion management is required. However, if a network is always congested,
bandwidth needs to be increased. Congestion management sends packet flows by using queuing
and scheduling.
An interface on the AR500 has four or eight default queues for outgoing packets. LAN-side
interfaces support the scheduling modes of priority queuing (PQ), deficit round robin (DRR),
weighted round robin (WRR), PQ+DRR, and PQ+WRR. WAN-side interfaces support the
scheduling modes of PQ, WFQ, PQ+WFQ, and class-based WFQ (CBQ). Each scheduling
algorithm schedules specific types of traffic, and affects bandwidth allocation, delay, and jitter.
Congestion Avoidance
Congestion avoidance is a flow control mechanism. A system configured with congestion
avoidance monitors network resource usage such as queues and memory buffers. When
congestion occurs or aggravates, the system discards packets.
The AR500 supports tail drop and WRED.
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Tail drop
When the queue length reaches the upper limit, the excess packets (buffered at the queue
tail) are discarded.
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WRED
WRED sets the upper and lower drop thresholds and the maximum drop probability for
each queue. When the queue length is smaller than the lower threshold, no packets are
discarded. When the length of the queue exceeds the upper threshold, all packets are
discarded. When the queue length is between the lower threshold and the upper threshold,
incoming packets are discarded randomly. The drop probability cannot be greater than the
maximum drop probability.
The AR500 uses the WRED based on queue profiles or traffic policies.
For details about QoS features, see
Feature Description - QoS
.
3.2.6 IPv6
The AR500 provides the IPv6 host function, which maximizes customers' return on investment
(ROI) and prevents repeated investment during network upgrade.
The AR500 supports the following IPv6 functions:
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IPv6 ND
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IPv6 PMTU
Huawei AR500 Industrial Switch Routers
Product Description
3 Product Characteristics
Issue 01 (2013-5-10)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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