Priority Mapping Overview - H3C S3610-28P Operation Manual

Operation Manual – QoS
H3C S3610&S5510 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 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 priority, 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.
For packets without 802.1q tags, the switch uses the priority of the receiving port as the
802.1p precedence of the received packets, and then obtains the local precedence of
the received packets by mapping the 802.1p precedence.
For packets with 802.1q tags, the switch provides the following two priority trust modes:
Trusting packet priority
The switch looks up the 802.1p precedence of the received packets in the
802.1p-precedence-to-local-precedence or 802.1p-precedence-to-drop-precedence
mapping table for the corresponding local precedence or drop precedence and assigns
the precedence to the received packets.
Trusting port priority
The switch uses the priority of the receiving port as the 802.1p precedence of the
received
802.1p-precedence-to-local-precedence or 802.1p-precedence-to-drop-precedence
mapping table for the corresponding local precedence or drop precedence, and then
assigns the precedence to the received packets.
The default 802.1p precedence to local precedence/drop precedence mapping table is
as shown below.
Chapter 5 Priority Mapping
packets, looks up the 802.1p
5-1
Chapter 5 Priority Mapping
precedence in the