Configuring Priority Mappings for IP Packets

This section describes how to configure priority mappings for IP 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 (DSCP values) in the IP 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.

BA classification is usually implemented on the core devices of the network. It can be implemented on both physical and logical interfaces. If implemented on the logical interface, BA classification can limit traffic congestion on member ports of the logical interface and restrict the precedence of packets on the logical interface.

A Diff-Serv (DS) domain is a group of Diff-Serv nodes that adopt the same service policies and implement the same PHB aggregate.

The precedence of packets is usually accepted or re-defined on the core router. On the border router in the IP domain or MPLS domain, DSCP and EXP also need to be mapped.

The BA classification can map the internal precedence to the external precedence, and the external precedence to the internal precedence. However, mapping between traffic of the same type, for example, IP traffic or MPLS traffic, is not supported.

Using the qos default-service-class command, you can configure the upstream traffic on the interface to enter the specific queues and provide service. After this command is run, other packets cannot be enabled to enter the queues, and BA classification cannot be enabled.

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

Configure the mappings between DSCP values of IP packets, service classes, and colors.

Run system-view
The system view is displayed.
Run diffserv domain { ds-domain-name | default | 5p3d } [ domain-id domain-id-value ]
A DiffServ domain is defined and the DiffServ domain view is displayed.

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

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

The system predefines a domain named default for IP packets. You are not allowed to delete the default domain.

If the priority mapping in Step 3 is not set in the DiffServ domain, the system uses the default mapping. The default domain describes the default mappings between the DSCP values, QoS service classes, and colors for IP packets. You can change the mappings in as required. In the default domain, the DSCP 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 DSCP values. Their mappings are shown in Table 2.

**Table 1** Default mappings between DSCP values and service classes in the default domain
DSCP	Service	Color	DSCP	Service	Color
00	BE	Green	32	AF4	Green
01	BE	Green	33	BE	Green
02	BE	Green	34	AF4	Green
03	BE	Green	35	BE	Green
04	BE	Green	36	AF4	Yellow
05	BE	Green	37	BE	Green
06	BE	Green	38	AF4	Red
07	BE	Green	39	BE	Green
08	AF1	Green	40	EF	Green
09	BE	Green	41	BE	Green
10	AF1	Green	42	BE	Green
11	BE	Green	43	BE	Green
12	AF1	Yellow	44	BE	Green
13	BE	Green	45	BE	Green
14	AF1	Red	46	EF	Green
15	BE	Green	47	BE	Green
16	AF2	Green	48	CS6	Green
17	BE	Green	49	BE	Green
18	AF2	Green	50	BE	Green
19	BE	Green	51	BE	Green
20	AF2	Yellow	52	BE	Green
21	BE	Green	53	BE	Green
22	AF2	Red	54	BE	Green
23	BE	Green	55	BE	Green
24	AF3	Green	56	CS7	Green
25	BE	Green	57	BE	Green
26	AF3	Green	58	BE	Green
27	BE	Green	59	BE	Green
28	AF3	Yellow	60	BE	Green
29	BE	Green	61	BE	Green
30	AF3	Red	62	BE	Green
31	BE	Green	63	BE	Green

Table 2 shows the default mappings between internal service classes, colors, and DSCP values for IP packets.

**Table 2** Default mappings between service classes and DSCP values
Service	Color	DSCP
BE	Green	0
AF1	Green	10
AF1	Yellow	12
AF1	Red	14
AF2	Green	18
AF2	Yellow	20
AF2	Red	22
AF3	Green	26
AF3	Yellow	28
AF3	Red	30
AF4	Green	34
AF4	Yellow	36
AF4	Red	38
EF	Green	46
CS6	Green	48
CS7	Green	56

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 { 5p3d | ds-domain-name | default } [ inbound | outbound ]
The DiffServ domain is bound to the interface, and BA classification is enabled on the interface.
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 DiffServ domain.
Run the display diffserv domain application ds-domain-name command to display the interface list applied to a DiffServ domain.