Priority Mapping Overview; Chapter 5 Priority Mapping - H3C S7500E Series Operation Manual

Operation Manual – QoS
H3C S7500E Series Ethernet Switches
When configuring priority mapping, go to these sections for information you are
interested in:

Priority Mapping Overview

Configuring a Priority Mapping Table
Configuring the Port Priority
Configuring Port Priority Trust Mode
Displaying and Maintaining Priority Mapping
5.1 Priority Mapping Overview
When a packet reaches a switch, the switch assigns the packet parameters according
to it configuration, such as 802.1p precedence, DSCP precedence, IP precedence,
local precedence, and drop precedence.
The local precedence and drop precedence are described as follows.
Local precedence is the precedence that the switch assigns to a packet and it is
corresponding to the number of an outbound queue on the port. Local precedence
takes effect only on the local switch.
Drop precedence is a parameter that is referred to when dropping packets. The
higher the drop precedence, the more likely a packet is dropped.
S7500E series Ethernet switches provide the following two priority trust modes:
Trusting the DSCP precedence of received packets. In this mode, the switch
searches the dscp-dot1p/dp/dscp mapping table based on the DSCP
precedence
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.
Trusting the 802.1p precedence of received packets. In this mode, if a packet is
received without an 802.1q tag, the switch takes the priority of the receiving port as
the 802.1p precedence of the packet and then based on the priority searches the
dot1p-dp/lp mapping table for the local/drop precedence for the packet. If packet
is received with an 802.1q tag, the switch searches the dot1p-dp/lp mapping table
based on the 802.1p precedence in the tag for local/drop precedence for the
packet.
The default dot1p-lp/dp mapping and dscp-dot1p/dp/dscp mapping provided by
S7500E series Ethernet switches are shown in the following two tables.

Chapter 5 Priority Mapping

of the received packet for the
5-1
Chapter 5 Priority Mapping
802.1p precedence/drop