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Troubleshooting VLT
To help troubleshoot different VLT issues that may occur, use the following information.
NOTE: For information on VLT Failure mode timing and its impact, contact your Dell Networking
representative.
Table 70. Troubleshooting VLT
Description Behavior at Peer Up Behavior During Run
Time
Action to Take
Bandwidth monitoring A syslog error message
and an SNMP trap is
generated when the
VLTi bandwidth usage
goes above the 80%
threshold and when it
drops below 80%.
A syslog error message
and an SNMP trap is
generated when the
VLTi bandwidth usage
goes above its threshold.
Depending on the traffic
that is received, the
traffic can be offloaded
inVLTi.
Domain ID mismatch
The VLT peer does not
boot up. The VLTi is
forced to a down state.
A syslog error message
and an SNMP trap are
generated.
The VLT peer does not
boot up. The VLTi is
forced to a down state.
A syslog error message
and an SNMP trap are
generated.
Verify the domain ID
matches on both VLT
peers.
Dell Networking OS
Version mismatch
A syslog error message
is generated.
A syslog error message
is generated.
Follow the correct
upgrade procedure for
the unit with the
mismatched Dell
Networking OS version.
Remote VLT port
channel status
N/A N/A Use the show vlt
detail and show vlt
brief
commands to
view the VLT port
channel status
information.
Spanning tree mismatch
at global level
All VLT port channels go
down on both VLT
peers. A syslog error
message is generated.
No traffic is passed on
the port channels.
A one-time
informational syslog
message is generated.
During run time, a loop
may occur as long as
the mismatch lasts.
To resolve, enable RSTP
on both VLT peers.
Spanning tree mismatch
at port level
A syslog error message
is generated.
A one-time
informational syslog
message is generated.
Correct the spanning
tree configuration on
the ports.
System MAC mismatch A syslog error message
and an SNMP trap are
generated.
A syslog error message
and an SNMP trap are
generated.
Verify that the unit ID of
VLT peers is not the
same on both units and
Virtual Link Trunking (VLT)
979