Figure 4 Priority mapping process for an Ethernet packet
Use port priority
as 802.1p priority
for priority
mapping
Look up dot1p-dp and
dot1p-lp mapping
tables
Mark the packet
with local
precedence or drop
precedence
For information about priority marking, see
Priority mapping configuration tasks
You can modify priority mappings by modifying priority mapping tables, priority trust mode on a port,
and port priority.
To configure priority mapping, perform the following tasks:
Tasks at a glance
(Optional.)
802.1p in
packets
No
Is the packet
802.1q tagged?
Yes
Look up dot1p-dp and
dot1p-lp mapping
tables
Mark the packet
with local
precedence or drop
precedence
Configuring a priority map
Receive a
packet on a port
Does the packet match
Yes
conditions for local
precedence or drop
precedence marking?
No
Which priority is
trusted on the port?
DSCP
in packets
Look up dscp-dp,
dscp-dot1p, and
dscp-dscp mapping
tables
Mark the packet
with 802.1p priority,
drop precedence,
and new DSCP
precedence
Look up dot1p-lp
mapping table
Mark the packet with
local precedence
Schedule the packet
according to its local
and drop precedence
"Configuring priority
marking."
27
Mark it with local
precedence or drop
precedence
Port priority
Use port priority
as 802.1p priority
for priority
mapping
Look up dot1p-dp and
dot1p-lp mapping
tables
Mark the packet
with local
precedence or drop
precedence