P Priority - HP 4800G Series Configuration Manual

802.1p Priority

802.1p priority lies in Layer 2 packet headers and is applicable to occasions where Layer 3 header
analysis is not needed and QoS must be assured at Layer 2.
Figure 12-2 An Ethernet frame with an 802.1Q tag header
As shown in Figure
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
Byte 1
TPID (Tag protocol identifier)
1 0 0 0 0 0 0 1 0 0 0 0 0 0 0
7 6 5 4 3 2 1 0 7
Table 12-6 Description on 802.1p priority
802.1p priority (decimal)
0
1
2
3
4
5
6
7
12-2, the 4-byte 802.1Q tag header consists of the tag protocol identifier (TPID, two
Byte 2
0 Priority
6 5 4 3 2 1 0 7
802.1p priority (binary)
000
001
010
011
100
101
110
111
Byte 3
TCI (Tag control information)
CFI
VLAN ID
6 5 4 3 2 1 0 7 6
12-5
Table 12-6 presents the values for
Byte 4
5 4 3 2 1 0
Description
best-effort
background
spare
excellent-effort
controlled-load
video
voice
network-management