Chapter 13 Bandwidth Management
P-660HW-Dx User’s Guide
194
13.10 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.
13.10.1 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 107
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.
PHB consists of two types of services: EF (Expedited Forwarding) and AF (Assured
Forwarding). EF has higher priority. EF guarantees services with minimal loss and delay. AF
has four sub-classes, each with three levels of importance (drop precedence). A high drop
precedence means low importance.
13.10.2 Rule Configuration
Click the Edit icon or select
User Defined
from the
Service
drop-down list in the
Rule Setup
screen to configure a bandwidth management rule. Use bandwidth rules to allocate specific
amounts of bandwidth capacity (bandwidth budgets) to specific applications and/or subnets.
DSCP
(6-bit)
Unused
(2-bit)
Table 77
Sub-Classes of AF Services
DIFFSERV PRIORITY
LOW DROP
PRECEDENCE
MEDIUM DROP
PRECEDENCE
HIGH DROP
PRECEDENCE
SUB-CLASS4
AF41
AF42
AF43
SUB-CLASS3
AF31
AF32
AF33
SUB-CLASS2
AF21
AF22
AF23
SUB-CLASS1
AF11
AF12
AF13
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Страница 10: ...Contents Overview P 660HW Dx User s Guide 10...
Страница 20: ...Table of Contents P 660HW Dx User s Guide 20...
Страница 26: ...List of Figures P 660HW Dx User s Guide 26...
Страница 31: ...31 PART I Introduction Introducing the ZyXEL Device 33 Introducing the Web Configurator 37...
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Страница 50: ...Chapter 2 Introducing the Web Configurator P 660HW Dx User s Guide 50...
Страница 51: ...51 PART II Wizards Wizard Setup for Internet Access 53 Bandwidth Management Wizard 67...
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Страница 66: ...Chapter 3 Wizard Setup for Internet Access P 660HW Dx User s Guide 66...
Страница 72: ...Chapter 4 Bandwidth Management Wizard P 660HW Dx User s Guide 72...
Страница 73: ...73 PART III Network WAN Setup 75 LAN Setup 93 Wireless LAN 105 Network Address Translation NAT Screens 129...
Страница 74: ...74...
Страница 92: ...Chapter 5 WAN Setup P 660HW Dx User s Guide 92...
Страница 141: ...141 PART IV Security Firewalls 143 Firewall Configuration 155 Content Filtering 177...
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Страница 162: ...Chapter 10 Firewall Configuration P 660HW Dx User s Guide 162 Figure 88 Firewall Edit Rule...
Страница 176: ...Chapter 10 Firewall Configuration P 660HW Dx User s Guide 176...
Страница 180: ...Chapter 11 Content Filtering P 660HW Dx User s Guide 180...
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Страница 186: ...Chapter 12 Static Route P 660HW Dx User s Guide 186...
Страница 202: ...Chapter 14 Dynamic DNS Setup P 660HW Dx User s Guide 202...
Страница 224: ...Chapter 16 Universal Plug and Play UPnP P 660HW Dx User s Guide 224...
Страница 225: ...225 PART VI Maintenance and Troubleshooting System 227 Logs 233 Tools 251 Diagnostic 257 Troubleshooting 259...
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Страница 232: ...Chapter 17 System P 660HW Dx User s Guide 232...
Страница 250: ...Chapter 18 Logs P 660HW Dx User s Guide 250...
Страница 256: ...Chapter 19 Tools P 660HW Dx User s Guide 256...
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Страница 270: ...Appendix A Product Specifications and Wall Mounting P 660HW Dx User s Guide 270 Figure 151 Masonry Plug and M4 Tap Screw...
Страница 330: ...Appendix F Internal SPTGEN P 660HW Dx User s Guide 330...
Страница 332: ...Appendix G Command Interpreter P 660HW Dx User s Guide 332...
Страница 344: ...Appendix J Splitters and Microfilters P 660HW Dx User s Guide 344...
Страница 350: ...Appendix L Legal Information P 660HW Dx User s Guide 350...
Страница 356: ...Appendix M Customer Support P 660HW Dx User s Guide 356...
Страница 364: ...Index P 660HW Dx User s Guide 364...