G-3000H User’s Guide
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Chapter 5 Wireless Configuration
5.3.2.1 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.
5.3.2.2 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.
DSCP is backward compatible with the three precedence bits in the ToS octet so that non-
DiffServ compliant, ToS-enabled network device will not conflict with the DSCP mapping.
Figure 20
DiffServ: Differentiated Service Field
The DSCP value determines the forwarding behavior, the PHB (Per-Hop Behavior), that each
packet gets across the DiffServ network. Based on the marking rule, different kinds of traffic
can be marked for different priorities of forwarding. Resources can then be allocated
according to the DSCP values and the configured policies.
5.3.3 ToS (Type of Service) and WMM QoS
The DSCP value of outgoing packets is between 0 and 255. 0 is the default priority. WMM
QoS checks the DSCP value in the header of data packets. It gives the traffic a priority
according to this number.
In order to control which priority level is given to traffic, the device sending the traffic must
set the DSCP value in the header. If the DSCP value is not specified, then the traffic is treated
as best-effort. This means the wireless clients and the devices with which they are
communicating must both set the DSCP value in order to make the best use of WMM QoS. A
Voice over IP (VoIP) device for example may allow you to define the DSCP value.
The following table lists which WMM QoS priority level the ZyAIR uses for specific DSCP
values.
DSCP
(6-bit)
Unused
(2-bit)
Table 11
ToS and IEEE 802.1d to WMM QoS Priority Level Mapping
DSCP VALUE
WMM QOS PRIORITY LEVEL
224, 192
voice
160, 128
video
Summary of Contents for ZyAIR G-3000H
Page 1: ...G 3000H 802 11g Wireless Access Point User s Guide Version 3 50 1 2006 ...
Page 22: ...G 3000H User s Guide 22 List of Figures ...
Page 26: ...G 3000H User s Guide 26 List of Tables ...
Page 114: ...G 3000H User s Guide 114 Chapter 9 VLAN ...
Page 134: ...G 3000H User s Guide 134 Chapter 11 Certificates ...
Page 164: ...G 3000H User s Guide 164 Chapter 15 Introducing the SMT ...
Page 180: ...G 3000H User s Guide 180 Chapter 17 LAN Setup ...
Page 218: ...G 3000H User s Guide 218 Chapter 24 System Maintenance and Information ...
Page 224: ...G 3000H User s Guide 224 Appendix C Power over Ethernet PoE Specifications ...
Page 226: ...G 3000H User s Guide 226 Appendix D Brute Force Password Guessing Protection ...
Page 238: ...G 3000H User s Guide 238 Appendix E Setting up Your Computer s IP Address ...
Page 242: ...G 3000H User s Guide 242 Appendix F IP Address Assignment Conflicts ...
Page 254: ...G 3000H User s Guide 254 Appendix G Wireless LANs ...
Page 262: ...G 3000H User s Guide 262 Appendix H IP Subnetting ...
Page 264: ...G 3000H User s Guide 264 Appendix I Command Interpreter ...
Page 268: ...G 3000H User s Guide 268 Appendix J Log Descriptions ...
Page 272: ...G 3000H User s Guide 272 Appendix L Power Adaptor Specifications ...
Page 280: ...G 3000H User s Guide 280 Appendix M Text File Based Auto Configuration ...
Page 294: ...G 3000H User s Guide 294 Appendix N Wireless LAN Manager ...
Page 299: ...G 3000H User s Guide Index 299 ZyNOS F W Version 196 zyxel prowireless mib 287 ...