H3C Technologies H3C MSR 50 - Manual (Page 282)

261
Appendix Packet precedences
IP precedence and DSCP values
Figure 261 DS field and ToS field
As shown in Figure 261 , the ToS field of 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 of the IP header is redefined as the
differentiated services (DS) field, where a differentiated service code point (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 121 Description on IP precedence
IP precedence (decimal) IP precedence (binary) Keyword
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 122 Description on DSCP values
DSCP value (decimal) DSCP value (binary) Keyword
46 101110 ef
10 001010 af11
12 001100 af12
14 001110 af13
18 010010 af21
20 010100 af22
22 010110 af23
26 011010 af31