![H3C S5120-SI Series Operation Manual Download Page 339](http://html2.mh-extra.com/html/h3c/s5120-si-series/s5120-si-series_operation-manual_3711174339.webp)
3-2
In this mode, the switch searches for the set of precedence values corresponding to the trusted type
(802.1p precedence or DSCP precedence) of priority of the packet in the corresponding priority
mapping tables and assigns the set of matching precedence values to the packet.
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, assigns the local precedence to the packet, and enqueues
the packet according to the local precedence value.
You can configure the priority trust mode of a port as required. The priority mapping process on a switch
is as shown in
Figure 3-1
.
Figure 3-1
Priority mapping process in the case of supporting trusting port priority
Y
N
Search for the set of precedence
values corresponding to the trusted
type of priority of the packet in the
corresponding priority mapping
tables and assigns the set of
matching precedence values to the
packet
Search for the local precedence
corresponding to the port priority
of the receiving port in the
802.1p-to-local precedence
mapping table, and assign the
local precedence to the packet
Trust port
priority
Packet
Trust packet
priority
Receiving
port
An S5120-SI series switch can trust one of the following two priority types:
z
Trusting the DSCP precedence of received packets. In this mode, the switch searches the
dscp-dot1p/dscp
mapping table based on the DSCP precedence of the received packet for the
802.1p precedence/DSCP precedence to be used to mark the packet. Then the switch searches
the
dscp-lp
mapping table based on the marked DSCP precedence for the corresponding local
precedence and marks the received packet with the local precedence.
z
Trusting the 802.1p precedence of received packets. In this mode, the switch searches the
dot1p-dot1p/dscp
mapping table based on the 802.1p precedence of the received packet for the
802.1p precedence/DSCP precedence to be used to mark the packet. Then the switch searches
the
dot1p-lp
mapping table based on the marked 802.1p precedence for the corresponding local
precedence and marks the received packet with the local precedence.
Introduction to Priority Mapping Tables
The device provides various types of priority mapping table, as listed below.
z
dot1p-dot1p
: 802.1p-precedence-to-802.1p-precedence mapping table.
z
dot1p-dscp
: 802.1p-precedence-to-DSCP mapping table.
z
dot1p-lp
: 802.1p-precedence-to-local-precedence mapping table.
z
dscp-dot1p
: DSCP-to-802.1p-precedence mapping table, which is applicable to only IP packets.
z
dscp-dscp
: DSCP-to-DSCP mapping table, which is applicable to only IP packets.
z
dscp-lp
: DSCP-to-local-precedence mapping table, which is applicable to only IP packets.
Table 3-1
and
Table 3-2
list the default priority mapping tables.