H3C Technologies H3C S12500 Series Switches - Manual (Page 93)

84
NOTE:
•
The mappings described in this section apply to both directions unless otherwise specified.
• The priority used for colored priority mapping table lookup depends on the configuration of trusted
priority on the port and the priority re-marking result.
Appendix C Introduction to packet precedences
IP precedence and DSCP values
Figure 20 ToS and DS fields
As shown in Figure 20 , the ToS field in the IP header contains 8 bits. The first 3 bits (0 to 2) represent IP
precedence from 0 to 7. According to RFC 2474, the ToS field is redefined as the differentiated services
(DS) field, where a DSCP value is represented by the first 6 bits (0 to 5) and is in the range 0 to 63. The
remaining 2 bits (6 and 7) are reserved.
Table 15 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
6 110 internet
7 111 network
Table 16 DSCP values
DSCP value (decimal) DSCP value (binary) Description
46 101110 ef
10 001010 af11
12 001100 af12