Operation Manual – QoS-QoS Profile
H3C S5600 Series Ethernet Switches
Chapter 1 QoS Configuration
1-8
Figure 1-4
802.1Q tag headers
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 1-4
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
The precedence is called 802.1p priority because the related applications of this
precedence are defined in detail in the 802.1p specifications.
3) Local
precedence
Local precedence is a locally significant precedence that the device assigns to a packet.
A local precedence value corresponds to one of the eight hardware output queues.
Packets with the highest local precedence are processed preferentially. As local
precedence is used only for internal queuing, a packet does not carry it after leaving the
queue.
II. Priority trust mode
After a packet enters a switch, the switch sets the 802.1p priority and local precedence
for the packet according to its own capability and the corresponding rules.
1)
For a packet carrying no 802.1q tag
When a packet carrying no 802.1q tag reaches the port of a switch, the switch replaces
the 802.1p priority of the received packet with the port priority, searches for the local