8
Miscellaneous
Layer 2 forwarding failure
Symptom
Layer 2 packet loss occurs when the switch forwards packets to a peer on the same network
segment and in the same VLAN.
Troubleshooting flowchart
Figure 4 Troubleshooting Layer 2 forwarding failure
Incoming error packets?
No
Yes
Yes
Troubleshoot the
problem
End
No
Yes
Layer 2 packet loss
Packets filtered by ACLs or
QoS policies?
Troubleshoot the
problem
Port blocked?
No
Troubleshoot the
problem
Yes
Port misconfigurations?
No
Locate and modify
misconfigurations
Yes
Port congestion?
No
Troubleshoot the
problem
Yes
Resolved?
No
No
No
No
No
Yes
Yes
Yes
Yes
Resolved?
Resolved?
Resolved?
Resolved?
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