Atc+Wmm From Wlan To Lan; Type Of Service (Tos); Diffserv; Dscp And Per-Hop Behavior - ZyXEL Communications NWA-3166 User Manual

8.3.3.2 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 27 ATC + WMM Priority Assignment (WLAN to LAN)
WMM VALUE
WMM_VOICE
WMM_VIDEO
WMM_BEST_EFFORT
WMM_BACKGROUN
D
NONE

8.3.4 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 NWA) so a server can decide the best method of
delivery, that is the least cost, fastest route and so on.

8.3.4.1 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.

8.3.4.2 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 69 DiffServ: Differentiated Service Field
NWA-3166 User's Guide
ATC VALUE
ATC_High
ATC_High
ATC_Medium
ATC_Low
ATC_Medium
DSCP Unused
(6-bit) (2-bit)
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