45 
Related commands 
This section lists the commands that you might use for troubleshooting Layer 3 forwarding failure. 
 
Command   Description 
debugging arp packet 
Enables ARP packet debugging. 
display arp 
Displays ARP entries. 
display
 
fib
 
Displays FIB entries 
display ip routing-table 
Displays the routing table. 
display mac
-
address
 
Displays MAC address entries 
 
Protocol flapping 
Symptom 
The switch cannot send or receive protocol packets. 
Troubleshooting flowchart 
Figure 22 Troubleshooting protocol flapping 
 
 
Solution 
To resolve the issue: 
1.  Verify that Layer 2 is operating correctly, as described in "Layer 2 forwarding failure." 
2.  Verify that Layer 3 is ope
rating correctly, as described in "Layer 3 forwarding failure." 
Layer 2 packet loss occurs?
Layer 3 packet loss occurs?
Troubleshoot the 
problem
Resolved?
Troubleshoot the 
problem
Contact the support
Layer 3 protocol flapping
Yes
No No
Yes
Resolved?
Yes Yes
No No
End
Software-related
packet loss occurs?
No
Yes
Collect diagnostic 
information