
25
Figure 5
Priority mapping procedure for an Ethernet packet
Which priority is
trusted on the
port?
Receive a packet
on a port
Use the port priority
as the 802.1p priority
for priority mapping
N
Look up the dot1p-
dscp and dot1p-lp
mapping tables
Mark the packet with
new DSCP
precedence and local
precedence
Is the packet
802.1q tagged?
Y
DSCP
in packets
Look up the dscp-lp,
dscp-dot1p, and dscp-
dscp mapping tables
802.1p
in packets
Mark the packet with
local precedence,
802.1p priority, and
new DSCP
precedence
Look up the dot1p-
dot1p, dot1p-dscp,
and dot1p-lp mapping
tables
Mark the packet with
new 802.1p priority,
new DSCP
precedence, and
local precedence
Schedule the packet
according to its local
precedence
Use the port
priority as the
802.1p priority for
priority mapping
Look up the dot1p-
dscp, and dot1p-lp
mapping tables
Mark the packet
with new DSCP
precedence and
local precedence
Port priority
NOTE:
This priority mapping procedure applies in the absence of priority marking. If priority marking is
configured, the device performs priority marking before priority mapping, and then uses the re-marked
packet-carried priority for priority mapping or directly uses the re-marked scheduling priority for traffic
scheduling depending on your configuration. Neither priority trust mode configuration on the port nor
port priority configuration takes effect.
Priority mapping configuration task list
You can modify priority mappings by modifying priority mapping tables, priority trust mode on a port,
and port priority.
H3C recommends that you plan QoS throughout the network before making QoS configuration.
Complete the following task to configure priority mapping:
Task Remarks
Configuring a priority mapping table
Optional
Configuring a port to trust packet priority for priority mapping
Optional
Changing the port priority of an interface
Optional