Link Flapping; Port Errdisabled - Cisco Nexus 1000V Troubleshooting Manual

Chapter 8 Ports
S e n d d o c u m e n t c o m m e n t s t o n e x u s 1 k - d o c f e e d b a c k @ c i s c o . c o m .

Link Flapping

When troubleshooting unexpected link flapping, it is important to have the following information:
•
•
•
Table 8-3
Possible Cause
The bit rate exceeds the
threshold and puts the port
into an error disabled state.
A hardware failure or
intermittent hardware error
causes a packet drop in the
switch.
A software error causes a
packet drop.
A control frame is erroneously
sent to the device.
ESX errors, or link flapping
on the upstream switch.

Port ErrDisabled

Use the guidelines in this section to troubleshoot ports that are error disabled.
Table 8-4
Possible Cause
Defective or damaged
cable.
OL-28795-01
Who initiated the link flap.
The actual reason for the link being down.
For a definition of link flapping, see the
Troubleshooting link flapping
Troubleshooting error disabled ports
Solution
"Link Flapping" section on page
Solution
Disable and then enable the port.
shut
no shut
The port should return to the normal state.
An external device may choose to initialize the link again when
encountering the error. If so, the exact method of link initialization
varies by device.
Determine the reason for the link flap as indicated by the MAC
1.
driver.
Use the debug facilities on the end device to troubleshoot the
2.
problem.
Use the troubleshooting guidelines in the documentation for your
ESX or upstream switch.
1. Verify the physical cabling.
Replace or repair defective cables.
2.
Re-enable the port.
3.
shut
no shut
Cisco Nexus 1000V Troubleshooting Guide, Release 4.2(1)SV2(2.1)
Problems with Ports
8-5.
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