39
DSCP value (decimal)
DSCP value (binary)
Description
14
001110
af13
18
010010
af21
20
010100
af22
22
010110
af23
26
011010
af31
28
011100
af32
30
011110
af33
34
100010
af41
36
100100
af42
38
100110
af43
8
001000
cs1
16
010000
cs2
24
011000
cs3
32
100000
cs4
40
101000
cs5
48
110000
cs6
56
111000
cs7
0
000000
be (default)
802.1p priority
802.1p priority lies in the Layer 2 header. It applies to occasions where Layer 3 header analysis is not
needed and QoS must be assured at Layer 2.
Figure 10 An Ethernet frame with an 802.1Q tag header
As shown in
, the 4-byte 802.1Q tag header contains the 2-byte tag protocol identifier
(TPID) and the 2-byte tag control information (TCI). The value of the TPID is 0x8100.
shows the format of the 802.1Q tag header. The Priority field in the 802.1Q tag header is called
802.1p priority, because its use is defined in IEEE 802.1p.
priority.
Destination
Address
Source
Address
802.1Q
header
TPID
Length
/Type
6 bytes
6 bytes
TCI
4 bytes
Data
FCS(CRC-
32)
2 bytes
4 bytes
46~1500 bytes