1.Common Causes
This fault is commonly caused by one of the following:
l The FR link is incorrectly configured.
l No packet is sent or received on the FR link.
l FR packets are incorrectly encapsulated.
2.Troubleshooting Flowchart
Figure 1-1 shows the troubleshooting flowchart.
Figure 1-1 Troubleshooting flowchart for a traffic forwarding fault on an FR link
3.Troubleshooting Procedure
Context
Saving the results of each troubleshooting step is recommended. If your troubleshooting fails to correct the fault, you will have a record of your actions to provide Huawei technical support personnel.
Procedure
Step 1 Check that the FR link is correctly configured.
If the FR link is incorrectly configured, configure it correctly according to 19.2.5.3.1 FR Frequently Flaps or Cannot Become Up and 19.2.5.3.2 Local Device Fails to Ping the Remote Device When the Link Protocol Status of Their Connected FR Interfaces Is Up.
If the fault persists, go to step 2.
Step 2 Check that packets are properly sent and received on the FR link.
1. Configure a traffic policy and apply this traffic policy to the FR link.
# Define the traffic classifier c1 to match packets with ACL 3999.
<Huawei> system-view
[Huawei] traffic classifier c1 operator and
[Huawei-classifier-c1] if-match acl 3999
# Enable the traffic statistics function in the traffic behavior b1.
<Huawei> system view
[Huawei] traffic behavior b1
[Huawei-behavior-b1] statistic enable
# In the traffic policy p1, bind the traffic classifier c1 to traffic behavior b1.
<Huawei> system-view
[Huawei] traffic policy p1
[Huawei-trafficpolicy-p1] classifier c1 behavior b1
[Huawei-trafficpolicy-p1] quit
# Apply this traffic policy to the inbound and outbound direction of Serial 1/0/0 on the FR link.
<Huawei> system-view
[Huawei] interface serial 1/0/0
[Huawei-Serial1/0/0] traffic-policy p1 inbound
[Huawei-Serial1/0/0] traffic-policy p1 outbound
2. Run the display traffic policy statistics command to check statistics on the traffic policy applied to Serial 1/0/0 to verify whether packets are properly sent and received on the FR link.
If the fault persists, go to step 3.
Step 3 Check where packets are discarded.
1. Run the debugging forward event counter command in the user view to enable debugging of error packet statistics in the forwarding plane.
2. Run the display forward all event counter command check statistics on error packets in the forwarding plane.
3. Determine whether packets are discarded in the forwarding plane based on error packet statistics in the forwarding plane and traffic statistics collected in Step 2.
Packets are discarded in the forwarding plane. If the fault persists, go to step 4.
Step 4 Check that packets are correctly encapsulated.
Check the packet encapsulation format packet by packet to verify whether packets are discarded by other components or on the intermediate transmission network.
Two methods are provided as follows:
l Run the debugging forward fr packet debug-num verbose command in the user view to enable debugging of encapsulation format of FR frames.
l Obtain packets on the FR interface and analyze the packet format.
Collect statistics on packet encapsulations, and go to step 5.
Step 5 Collect the following information and contact technical support personnel:
l Result of the preceding procedure
l Trap, log, and configuration information
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