Summary
By default, the AR2200-S does not trust any packet priority. If packets need to enter queues
based on packet priorities, the inbound interface must be configured to trust packet priorities.
Priority Mapping Is Incorrect Because the Trusted Priority Is Not Set
Fault Symptom
As shown in Figure 9-6, voice, video, and data services on the LAN of the enterprise are sent
to Eth 0/0/1 and Eth 0/0/0 on RouterA through SwitchA and SwitchB, and are sent to the WAN
through on RouterA.
RouterA identifies and processes service packets on the LAN based on 802.1p priorities in
packets. When packets reach the WAN from , RouterA needs to provide differentiated services
based on DSCP priorities in the packets. Priority mapping is configured so that RouterA can re-
mark 802.1p priorities with DSCP priorities.
Figure 9-6 Priority mappings are incorrect
After the configuration is complete, the DSCP priorities in voice, video, and data flows from
Switch B received on Router B are the same.
Fault Analysis
1. Capture packets sent from on RouterA. You can see that the DSCP priorities in voice, video,
and data flows from Switch B are 56.
2. Check whether priority mappings are correct.
Run the display qos map-table dot1p-dscp command to view the mappings between
802.1p priorities and DSCP priorities.
<RouterA> display qos map-table dot1p-dscp
Input Dot1p DSCP
-------------------
0 0
1 8
2 16
3 24
4 32
5 40
6 48
7 56
The preceding command output indicates that 802.1p priorities 2, 5, and 6 are mapped to
DSCP priorities 16, 40, and 48. The mappings are correct.
3. Check that the priority type trusted by the inbound interface is correct.
Run the display this command in the view of the inbound interface to check the
configuration of the inbound interface.
<RouterA> system-view
[RouterA] interface ethernet 0/0/0
[RouterA-Ethernet0/0/0] display this
#
trust 8021p
[RouterA] interface ethernet 0/0/1
[RouterA-Ethernet0/0/1] display this
#
trust 8021p
traffic-policy tp1 inbound
Huawei AR2200-S Series Enterprise Routers
Troubleshooting 9 QoS
Issue 01 (2012-01-06) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
246
To Next Page
Loading...
