VES-1616F-3x Series User’s Guide
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22
Differentiated Services
This chapter shows you how to configure Differentiated Services (DiffServ) on the switch.
22.1 DiffServ Overview
Quality of Service (QoS) is used to prioritize source-to-destination traffic flows. All packets in
the flow are given the same priority. You can use CoS (class of service) to give different
priorities to different packet types.
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.
22.1.1 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 66
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.
22.1.2 DiffServ Network Example
The following figure depicts a simple DiffServ network consisting of a group of contiguous
DiffServ-compliant network devices.
DSCP (6 bits)
DS (2 bits)
Summary of Contents for VDSL SWITCH VES-1616F-3X
Page 1: ...www zyxel com VES 1616F 3x Series VDSL Switch User s Guide Version 3 60 5 2007 Edition 2 ...
Page 2: ......
Page 7: ...Safety Warnings VES 1616F 3x Series User s Guide 7 ...
Page 8: ...Safety Warnings VES 1616F 3x Series User s Guide 8 ...
Page 28: ...List of Tables VES 1616F 3x Series User s Guide 28 ...
Page 30: ...30 ...
Page 34: ...Chapter 1 Getting to Know Your Switch VES 1616F 3x Series User s Guide 34 ...
Page 42: ...Chapter 3 Hardware Overview VES 1616F 3x Series User s Guide 42 ...
Page 44: ...44 ...
Page 62: ...Chapter 5 System Status and Port Statistics VES 1616F 3x Series User s Guide 62 ...
Page 84: ...Chapter 6 Basic Setting VES 1616F 3x Series User s Guide 84 ...
Page 86: ...86 ...
Page 106: ...Chapter 10 Spanning Tree Protocol VES 1616F 3x Series User s Guide 106 ...
Page 120: ...Chapter 15 Port Authentication VES 1616F 3x Series User s Guide 120 ...
Page 126: ...Chapter 17 Queuing Method VES 1616F 3x Series User s Guide 126 ...
Page 131: ...Chapter 18 Classifier VES 1616F 3x Series User s Guide 131 Figure 51 Classifier Example ...
Page 132: ...Chapter 18 Classifier VES 1616F 3x Series User s Guide 132 ...
Page 138: ...Chapter 19 Policy VES 1616F 3x Series User s Guide 138 Figure 53 Policy Example ...
Page 144: ...Chapter 20 VLAN Stacking VES 1616F 3x Series User s Guide 144 ...
Page 156: ...Chapter 21 Multicast VES 1616F 3x Series User s Guide 156 ...
Page 160: ...Chapter 22 Differentiated Services VES 1616F 3x Series User s Guide 160 ...
Page 161: ...161 PART IV Routing Protocol Static Route 163 DHCP Relay 165 ...
Page 162: ...162 ...
Page 168: ...168 ...
Page 178: ...Chapter 25 Maintenance VES 1616F 3x Series User s Guide 178 ...
Page 192: ...Chapter 27 Diagnostic VES 1616F 3x Series User s Guide 192 ...
Page 196: ...Chapter 28 Syslog VES 1616F 3x Series User s Guide 196 ...
Page 202: ...Chapter 29 Cluster Management VES 1616F 3x Series User s Guide 202 ...
Page 208: ...208 ...
Page 242: ...Chapter 32 Introducing the Commands VES 1616F 3x Series User s Guide 242 ...
Page 266: ...Chapter 34 IEEE 802 1Q Tagged VLAN Commands VES 1616F 3x Series User s Guide 266 ...
Page 274: ...Chapter 35 Troubleshooting VES 1616F 3x Series User s Guide 274 ...
Page 282: ...Chapter 36 Product Specifications VES 1616F 3x Series User s Guide 282 ...
Page 284: ...284 ...
Page 298: ...Appendix B Legal Information VES 1616F 3x Series User s Guide 298 ...