Hewlett Packard Enterprise FlexFabric 5940 Series, Руководство по настройке

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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 24 An Ethernet frame with an 802.1Q tag header
As shown in Figure 24 , 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. Figure 25 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.
Table 8 shows the values for 802.1p priority.
Figure 25 802.1Q tag header
Table 8 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
EXP values
The EXP field is in MPLS labels for MPLS QoS purposes. As shown in Figure 26 , the EXP field is
3-bit long and is in the range of 0 to 7.