Concept Guide

Troubleshooting VLT
To help troubleshoot dierent VLT issues that may occur, use the following information.
NOTE: For information on VLT Failure mode timing and its impact, contact your Dell EMC Networking representative.
Table 119. 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 trac that is
received, the trac can be
ooaded 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 EMC 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 EMC
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 trac 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
conguration 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 that the MAC address
is the same on both units.
Unit ID mismatch
The VLT peer does not boot up.
The VLTi is forced to a down
state.
A syslog error message is
generated.
The VLT peer does not boot up.
The VLTi is forced to a down
state.
A syslog error message is
generated.
Verify the unit ID is correct on
both VLT peers. Unit ID numbers
must be sequential on peer units;
for example, if Peer 1 is unit ID
“0”, Peer 2 unit ID must be “1’.
Version ID mismatch A syslog error message and an
SNMP trap are generated.
A syslog error message and an
SNMP trap are generated.
Verify the Dell EMC Networking
OS software versions on the VLT
peers is compatible. For more
Virtual Link Trunking (VLT) 1037