H3C S5120-EI Series User Manual

3-1
3 Priority Mapping
When configuring priority mapping, go to these sections for information you are interested in:
z Priority Overview
z Priority Mapping Overview
z Configuring a Priority Mapping Table
z Configuring the Port Priority
z Configuring Port Priority Trust Mode
z 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:
z The first three bits indicate IP precedence in the range of 0 to 7.
z Bit 3 to bit 6 indicate ToS precedence in the range of 0 to 15.
z 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

H3C S5120-EI Series Specifications

General

Brand	H3C
Model	S5120-EI Series
Category	Switch
Language	English