ZyXEL Communications ZyXEL ZyAIR NWA-3500 - Manual (Page 90)

Chapter 6 Wireless Configuration
ZyXEL NWA-3500 User’s Guide
90
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.
When ATC is activated, the device sends traffic with smaller packets before traffic with larger
packets if the network is congested.
ATC assigns priority to packets as shown in the following table.
You should activate ATC on the ZyXEL Device if your wireless network includes networking
devices that do not support WMM QoS, or if you want to prioritize traffic but do not want to
configure WMM QoS settings.
6.3.3 ATC+WMM
The ZyXEL Device can use a mapping mechanism to use both ATC and WMM QoS. The
ATC+WMM function prioritizes all packets transmitted onto the wireless network using
WMM QoS, and prioritizes all packets transmitted onto the wired network using ATC. See
Section 8.2.2 on page 123 for details of how to configure ATC+WMM.
Use the ATC+WMM function if you want to do the following:
• enable WMM QoS on your wireless network and automatically assign a WMM priority to
packets that do not already have one (see Section 6.3.3.1 on page 90 ).
• automatically prioritize all packets going from your wireless network to the wired network
(see Section 6.3.3.2 on page 91 ).
6.3.3.1 ATC+WMM from LAN to WLAN
ATC+WMM from LAN (the wired Local Area Network) to WLAN (the Wireless Local Area
Network) allows WMM prioritization of packets that do not already have WMM QoS
priorities assigned. The ZyXEL Device automatically classifies data packets using ATC and
then assigns WMM priorities based on that ATC classification.
Table 15 Typical Packet Sizes
APPLICATION
TIME
SENSITIVITY
TYPICAL PACKET SIZE
(BYTES)
Voice over IP (SIP) High < 250
Online Gaming High 60 ~ 90
Web browsing (http) Medium 300 ~ 600
FTP Low 1500
Table 16 Automatic Traffic Classifier Priorities
PACKET SIZE (BYTES) ATC PRIORITY
1 ~ 250 ATC_High
250 ~ 1100 ATC_Medium
1100 + ATC_Low