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GS-2024 User’s Guide
163
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H A P T E R
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 6-bit DSCP field which can define up to 64
service levels and the remaining 2 bits are defined as currently unused (CU). The following
figure illustrates the DS field.
Figure 85
DiffServ: Differentiated Service 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.
The DSCP value determines the PHB (Per-Hop Behavior), that each packet gets as it is
forwarded 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.
DSCP (6 bits)
CU (2 bits)
Summary of Contents for Dimension GS-2024
Page 2: ......
Page 7: ...Safety Warnings GS 2024 User s Guide 7 This product is recyclable Dispose of it properly ...
Page 8: ...Safety Warnings GS 2024 User s Guide 8 ...
Page 26: ...List of Tables GS 2024 User s Guide 26 ...
Page 28: ...28 ...
Page 36: ...Chapter 2 Hardware Installation and Connection GS 2024 User s Guide 36 ...
Page 44: ...44 ...
Page 62: ...Chapter 6 System Status and Port Statistics GS 2024 User s Guide 62 ...
Page 70: ...Chapter 7 Basic Setting GS 2024 User s Guide 70 Figure 27 Basic Setting IP Setup ...
Page 74: ...Chapter 7 Basic Setting GS 2024 User s Guide 74 ...
Page 76: ...76 ...
Page 88: ...Chapter 8 VLAN GS 2024 User s Guide 88 ...
Page 110: ...Chapter 13 Mirroring GS 2024 User s Guide 110 ...
Page 120: ...Chapter 15 Port Authentication GS 2024 User s Guide 120 ...
Page 138: ...Chapter 18 Multicast GS 2024 User s Guide 138 ...
Page 152: ...Chapter 19 Authentication Accounting GS 2024 User s Guide 152 ...
Page 157: ...157 PART IV IP Application Static Route 159 Differentiated Services 163 DHCP 167 ...
Page 158: ...158 ...
Page 162: ...Chapter 21 Static Route GS 2024 User s Guide 162 ...
Page 166: ...Chapter 22 Differentiated Services GS 2024 User s Guide 166 ...
Page 174: ...174 ...
Page 198: ...Chapter 25 Access Control GS 2024 User s Guide 198 ...
Page 200: ...Chapter 26 Diagnostic GS 2024 User s Guide 200 ...
Page 204: ...Chapter 27 Syslog GS 2024 User s Guide 204 ...
Page 218: ...218 ...
Page 222: ...Chapter 32 Troubleshooting GS 2024 User s Guide 222 ...
Page 230: ...Chapter 33 Product Specifications GS 2024 User s Guide 230 ...
Page 232: ...232 ...
Page 240: ...Appendix A Pop up Windows JavaScripts and Java Permissions GS 2024 User s Guide 240 ...
Page 252: ...Appendix C Legal Information GS 2024 User s Guide 252 ...
Page 258: ...Appendix D Customer Support GS 2024 User s Guide 258 ...
Page 266: ...Index GS 2024 User s Guide 266 ...