3Com 4210G Series Configuration Manual page 492

As shown in Figure 12-2, the 4-byte 802.1Q tag header consists of the tag protocol identifier (TPID,
two bytes in length), whose value is 0x8100, and the tag control information (TCI, two bytes in length).
Figure 12-3 presents 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.
802.1p priority.
Figure 12-3 802.1Q tag header
Table 12-6 Description on 802.1p priority
802.1p priority (decimal)
0
1
2
3
4
5
6
7
802.1p priority (binary)
000
001
010
011
100
101
110
111
12-8
Table 12-6 presents the values for
Description
best-effort
background
spare
excellent-effort
controlled-load
video
voice
network-management