Virtual link trunking (vlt) – Dell PowerEdge FX2/FX2s User Manual

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You can assign an interface to only one uplink-state group. Configure each
interface assigned to an uplink-state group as either an upstream or downstream
interface, but not both.

You can assign individual member ports of a port channel to the group. An uplink-
state group can contain either the member ports of a port channel or the port
channel itself, but not both.

Example

Dell(conf-uplink-state-group-16)# upstream tengigabitethernet

0/1-5

Dell(conf-uplink-state-group-16)#

Related
Commands

downstream

— assigns a port or port-channel to the uplink-state group as a

downstream interface.

uplink-state-group

— creates an uplink-state group and enables the tracking of

upstream links.

Virtual Link Trunking (VLT)

VLT allows physical links between two chassis to appear as a single virtual link to the network core. VLT
eliminates the requirement for Spanning Tree protocols by allowing link aggregation group (LAG)
terminations on two separate distribution or core switches, and by supporting a loop-free topology. VLT
provides Layer 2 multipathing, creating redundancy through increased bandwidth and enabling multiple
parallel paths between nodes and load-balancing traffic where alternative paths exist.

NOTE: When you launch the VLT link, the VLT peer-ship is not established if any of the following is
TRUE:

• The VLT System-MAC configured on both the VLT peers do not match.
• The VLT Unit-Id configured on both the VLT peers are identical.
• The VLT System-MAC or Unit-Id is configured only on one of the VLT peers.
• The VLT domain ID is not the same on both peers.

If the VLT peer-ship is already established, changing the System-MAC or Unit-Id does not cause VLT
peer-ship to go down.

Also, if the VLT peer-ship is already established and the VLT Unit-Id or System-MAC are configured
on both peers, then changing the CLI configurations on the VLT Unit-Id or System-MAC is rejected
if any of the following become TRUE:

• After making the CLI configuration change, the VLT Unit-Id becomes identical on both peers.
• After making the CLI configuration change, the VLT System-MAC do not match on both peers.

When the VLT peer-ship is already established, you can remove the VLT Unit-Id or System-MAC
configuration from either or both peers. However, removing configuration settings can cause the
VLT ports to go down if you configure the Unit-Id or System-MAC on only one of the VLT peers.

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