H3C LS-3100-52P-OVS-H3 Operation Manual - Priority Mapping
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Priority Mapping
When configuring priority mapping, go to these sections for information you are interested in:
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Priority Overview
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Priority Mapping Overview
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Configuring a Priority Mapping Table
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Configuring the Port Priority
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Configuring Port Priority Trust Mode
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Displaying and Maintaining Priority Mapping
Priority Overview
The following describes several types of precedence:
1) IP precedence, ToS precedence, and DSCP precedence
Figure 3-1 DS field and ToS field
The ToS field in an IP header contains eight bits, which are described as follows:
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The first three bits indicate IP precedence in the range of 0 to 7.
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Bit 3 to bit 6 indicate ToS precedence in the range of 0 to 15.
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RFC2474 re-defines the ToS field in the IP packet header, which is called the DS field. The first six
(bit 0 to bit 5) bits of the DS field indicate DSCP precedence in the range of 0 to 63. The last two bits
(bit 6 and bit 7) are reserved bits.
Table 3-1 Description on IP Precedence
IP Precedence (decimal)
IP Precedence (binary)
Description
0 000
Routine
1 001
priority
2 010
immediate
3 011
flash
4 100
flash-override
5 101
critical