1-6
DSCP value (decimal)
DSCP value (binary)
Description
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)
2) 802.1p
precedence
802.1p precedence 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 1-4
An Ethernet frame with an 802.1Q tag header
As shown in
Figure 1-4
, 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 1-5
presents the format of the 802.1Q tag header.
Figure 1-5
802.1Q tag header