Configuring Priority Mappings for MPLS Packets

This section describes how to configure priority mappings for MPLS packets and the application environment of this function.

Context

Traffic policy based on BA classification is used to map the precedence of traffic on one type of network to another type. That is, to transmit the traffic in the other network according to the original precedence.

When the NetEngine 8000 F serves as the border router for different networks, the original external priorities (EXP values) in the MPLS packets that go into the NetEngine 8000 F are all mapped to the internal priorities of the router represented by service classes of DiffServ and colors. When the NetEngine 8000 F sends out the packet, the internal priority is mapped back to the external priority.

Generally, the priority mappings of MPLS packets are configured on the core device of the network.

Pre-configuration Tasks

Before configuring traffic shaping, complete the following tasks:

Configuring the physical parameters of interfaces
Configuring the link layer attributes of interfaces to ensure their normal operation
Configuring IP addresses for interfaces
Enabling the routing protocol for communication between devices

This configuration is supported only on the Admin VS.

Procedure

Run system-view
The system view is displayed.
Run diffserv domain ds-domain-name [ domain-id domain-id ]
A DS domain is defined and the DS domain view is displayed.

Define traffic policies on the router based on the actual situation.

To define a traffic policy for incoming MPLS traffic, run the mpls-exp-inbound exp phb service-class [ color ] command.
To define a traffic policy for outgoing MPLS traffic, run the mpls-exp-outbound service-class color map exp-value command.

The system predefines a default domain. If you do not configure priority mappings in Step 3 for the DS domain, the system uses the default mappings. The default domain describes the default mappings from the EXP values of MPLS packets to QoS service classes and colors, or from QoS service classes and colors to the EXP values of MPLS packets. You can change the mappings in the default domain. The EXP values of the packets from an upstream device are mapped to QoS service classes and colors. Their mappings are shown in Table 1. The QoS service classes and colors of the packets entering a downstream device are mapped to EXP values. Their mappings are shown in Table 2.

The default mappings between the EXP values of MPLS packets and QoS service classes are shown in Table 1.

**Table 1** Default mappings between the EXP values the QoS service classes
EXP	Service	Color	EXP	Service	Color
0	BE	Green	4	AF4	Green
1	AF1	Green	5	EF	Green
2	AF2	Green	6	CS6	Green
3	AF3	Green	7	CS7	Green

The default mappings between the EXP values of MPLS packets and QoS service classes are shown in Table 2.

**Table 2** The default mappings between the EXP values and QoS service classes
Service	Color	MPLS EXP
BE	Green	0
AF1	Green, Yellow, Red	1
AF2	Green, Yellow, Red	2
AF3	Green, Yellow, Red	3
AF4	Green, Yellow, Red	4
EF	Green	5
CS6	Green	6
CS7	Green	7

Run commit
The configuration is committed.
Run quit
Return to the system view.
Run interface interface-type interface-number
The interface view is displayed.
Run trust upstream { ds-domain-name | default }
The DS domain is bound to the interface, and BA classification is enabled on the interface.
(Optional) Run mpls l2vc diffserv domain { 5p3d | domain-name | default }
A DS domain to which the private network label priority to be marked belongs is bound to a VLL interface.
Run quit
Return to the system view.
(Optional) Run slot slot-id
The slot view is displayed.
(Optional) Run mpls-inner-exp phb disable vll
The function of obtaining the private network label priority from a DS domain for the downstream traffic on the PW interface is disabled in the VLL networking.
Run commit
The configuration is committed.

Verifying the Configuration

Run the following commands to check the previous configuration.

Run the display diffserv domain [ ds-domain-name ] [ 8021p | dscp | exp ] [ inbound| outbound ] command to display the configurations of a DS domain.
Run the display diffserv domain application ds-domain-name command to display the interface list applied to a DS domain.