ZyXEL Communications NWA-3550, NWA-3500 8.5.7 ATC, 8.5.6.1 WMM QoS Priorities

Chapter 8 Wireless Configuration

reductions in data transmission for applications that are sensitive to latency (delay) and jitter (variations in delay).

8.5.6.1 WMM QoS Priorities

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

Table 32 WMM QoS Priorities

PRIORITY LEVEL	DESCRIPTION
voice	Typically used for traffic that is especially sensitive to jitter. Use
(WMM_VOICE)	this priority to reduce latency for improved voice quality.
video	Typically used for traffic which has some tolerance for jitter but
(WMM_VIDEO)	needs to be prioritized over other data traffic.
best effort	Typically used for traffic from applications or devices that lack
(WMM_BEST_EFFORT	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	This is typically used for non-critical traffic such as bulk transfers
(WMM_BACKGROUND	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.

8.5.7 ATC

Automatic Traffic Classifier (ATC) is a bandwidth management tool that prioritizes data packets sent across the network. ATC assigns each packet a priority and then queues the packet accordingly. Packets assigned a high priority are processed more quickly than those with low priority if there is congestion, allowing time- sensitive applications to flow more smoothly. Time-sensitive applications include both those that require a low level of latency and a low level of jitter such as Voice over IP or Internet gaming, and those for which jitter alone is a problem such as Internet radio or streaming video.

ATC assigns priority based on packet size, since time-sensitive applications such as Internet telephony (Voice over IP or VoIP) tend to have smaller packet sizes than non-time sensitive applications such as FTP (File Transfer Protocol). The following table shows some common applications, their time sensitivity, and their typical data packet sizes. Note that the figures given are merely examples - sizes may differ according to application and circumstances.

Table 33 Typical Packet Sizes

APPLICATION	TIME	TYPICAL PACKET
	SENSITIVITY	SIZE (BYTES)
Voice over IP (SIP)	High	< 250
Online Gaming	High	60 ~ 90

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	NWA-3500/NWA-3550 User’s Guide