ZyXEL nbg-334sh Manuel D’Utilisation

Chapter 5 Wireless LAN

ZyXEL NBG-334SH User’s Guide

When you select WPA2 or WPA2-PSK in your ZyXEL Device, you can also select an option 
(WPA Compatible) to support WPA as well. In this case, if some wireless clients support 
WPA and some support WPA2, you should set up WPA2-PSK or WPA2 (depending on the 
type of wireless network login) and select the WPA Compatible option in the ZyXEL Device.
Many types of encryption use a key to protect the information in the wireless network. The 
longer the key, the stronger the encryption. Every wireless client in the wireless network must 
have the same key.

This section discusses the Quality of Service (QoS) features available on the ZyXEL Device.

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).

The following table describes the WMM QoS priority levels that the ZyXEL Device uses.

Table 22   WMM QoS Priorities

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.