3Com S7906E Configuration Manual page 1809

As shown in Figure 13-1, the ToS field of the IP header contains eight bits, and the first three 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 DSCP value is represented by the first six
bits (0 to 5) and is in the range 0 to 63. The remaining two bits (6 and 7) are reserved.
Table 13-20 Description on IP precedence
IP precedence (decimal)
0
1
2
3
4
5
6
7
Table 13-21 Description on DSCP values
DSCP value (decimal)
46
10
12
14
18
20
22
26
28
30
34
36
38
8
16
24
32
40
48
56
IP precedence (binary)
000
001
010
011
100
101
110
111
DSCP value (binary)
101110
001010
001100
001110
010010
010100
010110
011010
011100
011110
100010
100100
100110
001000
010000
011000
100000
101000
110000
111000
13-10
Description
Routine
priority
immediate
flash
flash-override
critical
internet
network
Description
ef
af11
af12
af13
af21
af22
af23
af31
af32
af33
af41
af42
af43
cs1
cs2
cs3
cs4
cs5
cs6
cs7