Chapter 6 Wireless Configuration

The following table shows how priorities are assigned for packets coming from the LAN to the WLAN.

Table 18 ATC + WMM Priority Assignment (LAN to WLAN)

PACKET SIZE (BYTES)

 

 

 

ATC VALUE

 

 

 

WMM VALUE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1 ~ 250

 

 

 

ATC_High

 

 

 

WMM_VIDEO

 

 

 

 

 

 

 

 

 

250 ~ 1100

 

 

 

ATC_Medium

 

 

 

WMM_BEST_EFFORT

 

 

 

 

 

 

 

 

 

1100 +

 

 

 

ATC_Low

 

 

 

WMM_BACKGROUND

 

 

 

 

 

 

 

 

 

6.3.3.2 ATC+WMM from WLAN to LAN

ATC+WMM from WLAN to LAN automatically prioritizes (assigns an ATC value to) all packets coming from the WLAN. Packets are assigned an ATC value based on their WMM value, not their size.

The following table shows how priorities are assigned for packets coming from the WLAN to the LAN when using ATC+WMM.

Table 19 ATC + WMM Priority Assignment (WLAN to LAN)

WMM VALUE

 

 

 

 

ATC VALUE

 

 

 

 

 

 

WMM_VOICE

 

 

 

 

ATC_High

 

 

 

 

 

 

WMM_VIDEO

 

 

 

 

ATC_High

 

 

 

 

 

 

WMM_BEST_EFFORT

 

 

 

 

ATC_Medium

 

 

 

 

 

 

WMM_BACKGROUND

 

 

 

 

ATC_Low

 

 

 

 

 

 

NONE

 

 

 

 

ATC_Medium

 

 

 

 

 

 

6.3.4 Type Of Service (ToS)

Network traffic can be classified by setting the ToS (Type Of Service) values at the data source (for example, at the ZyXEL Device) so a server can decide the best method of delivery, that is the least cost, fastest route and so on.

6.3.4.1 DiffServ

DiffServ is a class of service (CoS) model that marks packets so that they receive specific per- hop treatment at DiffServ-compliant network devices along the route based on the application types and traffic flow. Packets are marked with DiffServ Code Points (DSCPs) indicating the level of service desired. This allows the intermediary DiffServ-compliant network devices to handle the packets differently depending on the code points without the need to negotiate paths or remember state information for every flow. In addition, applications do not have to request a particular service or give advanced notice of where the traffic is going.

6.3.4.2 DSCP and Per-Hop Behavior

DiffServ defines a new DS (Differentiated Services) field to replace the Type of Service (TOS) field in the IP header. The DS field contains a 2-bit unused field and a 6-bit DSCP field which can define up to 64 service levels. The following figure illustrates the DS field.

Figure 47 DiffServ: Differentiated Service Field

DSCP

Unused

(6-bit)

(2-bit)

 

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