DSCP value (decimal)
28
30
34
36
38
8
16
24
32
40
48
56
0
802.1p priority
802.1p priority lies in the Layer 2 header and applies to occasions where Layer 3 header analysis is not
needed and QoS must be assured at Layer 2.
Figure 28 An Ethernet frame with an 802.1Q tag header
As shown in
in length), whose value is 0x8100, and the tag control information (TCI, 2 bytes in length).
shows the format of the 802.1Q tag header. The Priority field in the 802.1Q tag header is called the
"802.1p priority", because its use is defined in IEEE 802.1p.
priority.
Figure 29 802.1Q tag header
Figure
28, the 4-byte 802.1Q tag header consists of the tag protocol identifier (TPID, 2 bytes
DSCP value (binary)
011100
011110
100010
100100
100110
001000
010000
011000
100000
101000
110000
111000
000000
86
Description
af32
af33
af41
af42
af43
cs1
cs2
cs3
cs4
cs5
cs6
cs7
be (default)
Table 12
shows the values for 802.1p
Figure 29