Operation Manual – QoS-QoS Profile
H3C S3100 Series Ethernet Switches
Chapter 1 QoS Configuration
1-8
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 a port, the switch replaces the 802.1p
priority of the received packet with the port priority, searches for the local precedence
corresponding to the port priority of the receiving port in the 802.1p-to-local precedence
mapping table, and assigns the local precedence to the packet.
2)
For an 802.1q tagged packet
For incoming 802.1q tagged packets, you can configure the switch to trust packet
priority with the
priority trust
command or to trust port priority with the
undo priority
trust
command. By default, the S3100 series switches trust port priority.
z
Trusting port priority
In this mode, the switch replaces the 802.1p priority of the received packet with the port
priority, searches for the local precedence corresponding to the port priority of the
receiving port in the 802.1p-to-local precedence mapping table, and assigns the local
precedence to the packet.
z
Trusting packet priority
After configuring to trust packet priority, you can specify the trusted priority type, which
can be 802.1p priority, DSCP precedence, or IP precedence. With trusting packet
priority enabled, the switch trusts the 802.1p priority of received packets.
Table 1-5
describes the three trusted packet priority types.
Table 1-5
Description on the three trusted packet priority types
Trusted priority
type
Description
802.1p priority
The switch searches for the local precedence
corresponding to the 802.1p priority of the packet in the
802.1p-to-local precedence mapping table and assigns the
local precedence to the packet.