How can packets be delivered to queues with different priorities

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AR delivers packets to different queues based on the priority. By default, the AR interfaces do not trust any packet priority. Packets received on the same interface are delivered to the same queue.


Packets enter queues of different priorities when the following requirements are met:

  • The trust command is used on the interface to map packets based on the priority.
  • Packets of different priorities exist in the service flows passing the interface.

NOTE:

You can run the following commands to re-mark a priority of a packet.

  • remark 8021p: Re-marks the 802.1p priority of VLAN packets.
  • remark dscp: Re-marks the DSCP priority of IP packets.
  • remark local-precedence: Re-marks the internal priority of packets.

Other related questions:
How does an AR send packets with high DSCP value to high-priority queues?
In a traffic classifier, configure the AR to send packets with the high DSCP value to EF queues so that the packets are preferentially processed. For example, configure the AR to send packets with the DSCP value of 22 to EF queues. [Huawei] traffic classifier c1 [Huawei-classifier-c1] if-match dscp 22 [Huawei-classifier-c1] quit [Huawei] traffic behavior b1 [Huawei-behavior-b1] queue ef bandwidth 100 cbs 2500 [Huawei-behavior-b1] quit [Huawei] traffic policy p1 [Huawei-trafficpolicy-p1] classifier c1 behavior b1

How does an AR send packets with a specific DSCP to high-priority queues

Use traffic classifiers to enable packets with high differentiated services code point (DSCP) values to enter expedited forwarding (EF) queues, and to ensure that the packets are transmitted preferentially. For example, to enable packets with a DSCP of 22 to enter EF queues, configure the following:

[Huawei] traffic classifier c1 [Huawei-classifier-c1] if-match dscp 22 [Huawei-classifier-c1] quit [Huawei] traffic behavior b1 [Huawei-behavior-b1] queue ef bandwidth 100 cbs 2500 [Huawei-behavior-b1] quit [Huawei] traffic policy p1 [Huawei-trafficpolicy-p1] classifier c1 behavior b1

What are the mappings between WMM queues and 802.1p priorities
WMM classifies data packets into four queues. 802.1P provides eight priorities. Users can configure the mappings between WMM queues and 802.1p priorities.

Mapping between differentiated services code point (DSCP) and local priority
IP packets carry the DSCP field to indicate the QoS preference. The mapping between the priority fields must be configured on the gateway to retain packet priorities when the packets traverse different networks. You can run the display qos map-table command to view the mapping between priorities, or run the input command in the priority mapping table view to configure the mapping between priorities.

Default mappings between priorities on an AR
Default mappings between priorities on an AR are as follows: For the AR120&AR150&AR160&AR200&AR500 series, AR510 series, AR1200 series, AR2204, AR2220L, and AR2220E, table 1 shows the mappings from 802.1p priorities to DSCP priorities, and the mappings between 802.1p priorities remain unchanged. Table 3 lists the mappings from DSCP priorities to 802.1p priorities, and the mappings between DSCP priorities remain unchanged. The mappings between MPLS EXP priorities remain unchanged. For AR2201-48FE, AR2202-48FE, AR2220, AR2240, and AR3200&AR3600 series, table 2 lists the mappings from 802.1p priorities to DSCP priorities and local priorities, and the mappings between 802.1p priorities remain unchanged. Table 4 lists the mappings from DSCP priorities to 802.1p priorities and local priorities, and the mappings between DSCP priorities remain unchanged. Table 5 lists the mappings from MPLS EXP priorities to local priorities, and the mappings between MPLS EXP priorities remain unchanged.

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