3Com 4210 9-Port Configuration Manual page 463

Best Effort (BE) class: This class is a special class without any assurance in the CS class. The AF
class can be degraded to the BE class if it exceeds the limit. Current IP network traffic belongs to
this class by default.
Table 1-3 Description on DSCP precedence values
DSCP value (decimal)
46
10
12
14
18
20
22
26
28
30
34
36
38
8
16
24
32
40
48
56
0
2) 802.1p priority
802.1p priority lies in Layer 2 packet headers and is applicable to occasions where the Layer 3 packet
header does not need analysis but QoS must be assured at Layer 2.
Figure 1-3 An Ethernet frame with an 802.1Q tag header
As shown in the figure above, each host supporting 802.1Q protocol adds a 4-byte 802.1Q tag header
after the source address of the former Ethernet frame header when sending packets.
DSCP value (binary)
101110
001010
001100
001110
010010
010100
010110
011010
011100
011110
100010
100100
100110
001000
010000
011000
100000
101000
110000
111000
000000
1-5
Description
ef
af11
af12
af13
af21
af22
af23
af31
af32
af33
af41
af42
af43
cs1
cs2
cs3
cs4
cs5
cs6
cs7
be (default)