ZyXEL Communications G-570S, Руководство пользователя

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Chapter 7 Wireless Screens
ZyXEL G-570S User’s Guide
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7.5 Quality of Service
This section discusses the Quality of Service (QoS) features available on the ZyXEL Device.
7.5.1 WMM QoS
WMM (Wi-Fi MultiMedia) QoS (Quality of Service) ensures quality of service in wireless
networks. It controls WLAN transmission priority on packets to be transmitted over the
wireless network.
WMM QoS prioritizes wireless traffic according to delivery requirements. WMM QoS is a
part of the IEEE 802.11e QoS enhancement to certified Wi-Fi wireless networks.
On APs without WMM QoS, all traffic streams are given the same access priority to the
wireless network. If the introduction of another traffic stream creates a data transmission
demand that exceeds the current network capacity, then the new traffic stream reduces the
throughput of the other traffic streams.
The ZyXEL Device uses WMM QoS to prioritize traffic streams according to the IEEE 802.1q
tag or DSCP information in each packet’s header. The ZyXEL Device automatically
determines the priority to use for an individual traffic stream. This prevents reductions in data
transmission for applications that are sensitive to latency (delay) and jitter (variations in
delay).
7.5.1.1 WMM QoS Priorities
The following table describes the WMM QoS priority levels that the ZyXEL Device uses.
Fragmentation
Threshold
A small fragmentation threshold is recommended for busy networks, while a
larger threshold provides faster performance if the network is not very busy.
Roaming If you have two or more ZyXEL Devices (or other wireless access points) on
your wireless network, you can enable this option so that wireless devices can
change locations without having to log in again. This is useful for devices,
such as notebooks, that move around a lot.
Table 12 Additional Wireless Terms
TERM DESCRIPTION
Table 13 WMM QoS Priorities
PRIORITY LEVEL DESCRIPTION
voice
(WMM_VOICE) Typically used for traffic that is especially sensitive to jitter. Use this priority
to reduce latency for improved voice quality.
video
(WMM_VIDEO) Typically used for traffic which has some tolerance for jitter but needs to be
prioritized over other data traffic.
best effort
(WMM_BEST_EFFORT) Typically used for traffic from applications or devices that lack QoS
capabilities. Use best effort priority for traffic that is less sensitive to latency,
but is affected by long delays, such as Internet surfing.
background
(WMM_BACKGROUND) This is typically used for non-critical traffic such as bulk transfers and print
jobs that are allowed but that should not affect other applications and users.
Use background priority for applications that do not have strict latency and
throughput requirements.