GS-2750 User’s Guide
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C
H A P T E R
19
Policy Rule
This chapter shows you how to configure policy rules.
19.1 Policy Rules Overview
A classifier distinguishes traffic into flows based on the configured criteria (refer to
Chapter
18 on page 145
for more information). A policy rule ensures that a traffic flow gets the
requested treatment in the network.
19.1.1 DiffServ
DiffServ (Differentiated Services) 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.
19.1.2 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.
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 kinds of forwarding. Resources can then be allocated according to
the DSCP values and the configured policies.
DSCP (6 bits)
Unused (2 bits)
Summary of Contents for GS-2750
Page 2: ......
Page 7: ...Safety Warnings GS 2750 User s Guide 7 This product is recyclable Dispose of it properly ...
Page 8: ...Safety Warnings GS 2750 User s Guide 8 ...
Page 26: ...List of Figures GS 2750 User s Guide 26 ...
Page 32: ...32 ...
Page 40: ...Chapter 2 Hardware Installation and Connection GS 2750 User s Guide 40 ...
Page 48: ...48 ...
Page 58: ...Chapter 4 The Web Configurator GS 2750 User s Guide 58 ...
Page 64: ...Chapter 5 Initial Setup Example GS 2750 User s Guide 64 ...
Page 70: ...Chapter 6 System Status and Port Statistics GS 2750 User s Guide 70 ...
Page 82: ...Chapter 7 Basic Setting GS 2750 User s Guide 82 ...
Page 84: ...84 ...
Page 120: ...Chapter 11 Spanning Tree Protocol GS 2750 User s Guide 120 ...
Page 134: ...Chapter 15 Link Aggregation GS 2750 User s Guide 134 ...
Page 144: ...Chapter 17 Port Security GS 2750 User s Guide 144 ...
Page 155: ...Chapter 19 Policy Rule GS 2750 User s Guide 155 Figure 73 Policy Example example ...
Page 156: ...Chapter 19 Policy Rule GS 2750 User s Guide 156 ...
Page 160: ...Chapter 20 Queuing Method GS 2750 User s Guide 160 ...
Page 166: ...Chapter 21 VLAN Stacking GS 2750 User s Guide 166 ...
Page 194: ...Chapter 23 Authentication Accounting GS 2750 User s Guide 194 ...
Page 220: ...220 ...
Page 232: ...Chapter 28 Differentiated Services GS 2750 User s Guide 232 ...
Page 242: ...Chapter 29 DHCP GS 2750 User s Guide 242 ...
Page 252: ...Chapter 30 VRRP GS 2750 User s Guide 252 ...
Page 254: ...254 ...
Page 278: ...Chapter 32 Access Control GS 2750 User s Guide 278 ...
Page 280: ...Chapter 33 Diagnostic GS 2750 User s Guide 280 ...
Page 284: ...Chapter 34 Syslog GS 2750 User s Guide 284 ...
Page 298: ...Chapter 39 Routing Table GS 2750 User s Guide 298 ...
Page 301: ...301 PART VI Product Specifications Product Specifications 303 ...
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Page 322: ...Appendix B Legal Information GS 2750 User s Guide 322 ...
Page 328: ...Appendix C Customer Support GS 2750 User s Guide 328 ...