H3C LS-3100-52P-OVS-H3 Operation Manual - page 1269
3-3
DSCP value (decimal)
DSCP value (binary)
Description
56 111000
cs7
0 000000
be
(default)
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 3-2 An Ethernet frame with an 802.1Q tag header
As shown in
Figure 3-2
, the 4-byte 802.1Q tag header contains a 2-byte Tag Protocol Identifier (TPID)
whose value is 8100 and a 2-byte Tag Control Information (TCI). TPID is a new class defined by IEEE to
indicate a packet with an 802.1Q tag.
Figure 3-3
describes the detailed contents of an 802.1Q tag
header.
Figure 3-3 802.1Q tag header
In the figure above, the 3-bit priority field in TCI is 802.1p priority in the range of 0 to 7. In the figure
above, the priority field (three bits in length) in TCI is 802.1p priority (also known as CoS precedence),
which ranges from 0 to 7.
Table 3-3 Description on 802.1p priority
802.1p priority (decimal)
802.1p priority (binary)
Description
0 000
best-effort
1 001
background
2 010
spare
3 011
excellent-effort
4 100
controlled-load
5 101
video
6 110
voice
7 111
network-management