Command Line Reference Guide

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Virtual Link Trunking (VLT)
Virtual link trunking (VLT) is supported on the Dell Networking S5000 switch.
Virtual link trunking allows physical links between two chassis to appear as a single virtual link to the network core or
other switches such as Edge, Access, or top-of-rack (ToR). VLT reduces the role of the spanning tree protocols by
allowing link aggregation group (LAG) terminations on two separate distribution or core switches, and by supporting a
loop-free topology. (You still need a spanning tree protocol to prevent the initial loop that may occur prior to VLT being
established. After VLT is established, you may use the rapid spanning treee protocol (RSTP) to prevent loops from
forming with new links that are incorrectly connected and outside the VLT domain.) 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.
Prerequisites: Before you configure VLT, make sure that both VLT peer switches are running the same Dell Networking
operating software (FTOS) version and are configured for RSTP as described in the ”Virtual Link Trunking (VLT)” chapter
in the FTOS Configuration Guide .
CAUTION: Dell Networking recommends not enabling Stacking and VLT simultaneously. If you enable both at the
same time, unexpected behavior occurs.
back-up destination
Configure the IP address of the management interface on the remote VLT peer to be used as the endpoint of the VLT
backup link for sending out-of-band hello messages.
S5000
Syntax
back-up destination ip-address [interval seconds]
Parameters
ip-address Enter an IP address in dotted decimal format.
interval seconds Enter the keyword interval to specify the time interval used to
send hello messages. The range is 1 to 5 seconds.
Defaults 1 second
Command Modes VLT DOMAIN
Command History
Version 9.0(1.3) Introduced on the S5000.
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