Web Management Guide-R02

Table Of Contents
Chapter 9
| Class of Service
Layer 3/4 Priority Settings
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To show the CoS/CFI to internal PHB/drop precedence map:
1. Click Traffic, Priority, CoS to DSCP.
2. Select Show from the Action list.
3. Select a port.
Figure 156: Showing CoS to DSCP Internal Mapping
Mapping IP
Precedence Values to
Internal DSCP Values
Use the Traffic > Priority > IP Precedence to DSCP page to map IP precedence
values in incoming packets to per-hop behavior and drop precedence values for
priority processing.
The Type of Service (ToS) octet in the IPv4 header includes three precedence bits
defining eight different priority levels ranging from highest priority for network
control packets to lowest priority for routine traffic. The default IP Precedence
values map one-to-one to the Class of Service values (that is, Precedence value 0
maps to PHB value 0, and so forth). Bits 6 and 7 are used for network control, and
the other bits for various application types. The ToS bits are defined in Table 18.
Table 18: Mapping IP Precedence
Priority Level Traffic Type
7Network Control
6 Internetwork Control
5Critical