Configuration Guide Configuring WQoS
Fair scheduling allows STAs in the same frequency band of the same AP to share the wireless network resources provided
by the AP fairly. The fair scheduling function can prevent low-speed STAs from decreasing the throughput of the entire
wireless network, and provide smoother network experience for STAs. Besides, the fair scheduling function provides users
with better experience by monitoring changes in the traffic of each STA intelligently and adjusting the proportion of the
wireless bandwidth used by each STA dynamically. In software version later than 10.4(1T19)p1, different priorities can be
configured for STAs in fair scheduling so that specified users can preferentially enjoy the wireless bandwidth.
Overview
Limit the rates of an AP, a WLAN, or a STA to that the rate does not exceed the limit.
Associate a STA with other STAs in the same frequency band of the same AP to share the wireless
network resources provided by the AP, thus sharing the bandwidth of the wireless network in a fair
manner.
1.3.1 Rate Limiting
Rate limiting is used to limit the rates of an AP, a WLAN, or a STA to ensure that the rate does not exceed a certain range.
Working Principle
Rate limiting is implemented based on the token bucket.
The token bucket records the number of bytes that can pass in a certain period of time.
In each period, the number of data bytes that can pass is calculated based on the configured CIR and CBS, thereby
adjusting the size of the token bucket.
When a packet arrives, the packet size in bytes is compared with the size of the token bucket. When the packet size is
smaller than that of the token bucket, the packet is allowed to pass, and the token bucket size decreases with the
corresponding amount. When the packet size is greater than that of the token bucket, the packet is buffered and
transmitted after obtaining permission by the token bucket. Traffic Shaping smoothens the traffic with low fluctuation.
Currently, on an AP, Traffic Shaping is used to implement rate limiting of an AP, a STA, or a WLAN.
1.3.2 Fair Scheduling
Fair scheduling, by dividing the time equally, resolves the problem that some nodes occupy the air interfaces for a longer
time, particularly low-rate nodes.
Working Principle
Owing to the special characteristics of the wireless network, STAs (including APs) on the same network share the air
interface resources, which is also a bottleneck of STA performance. This is one of the differences between the wired and
wireless networks. Traditional packet scheduling often adopts the first in first out (FIFO) mode. On one wireless network,
every STA that needs to transmit data want to occupy the air interface resources whenever possible. Transmission of
overwhelming low-rate packets results in long-time occupation of the air interfaces. Thereby, the lasting queue take-up
causes packet loss and degrades the overall performance of the network.
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