The Flexlink+ feature enables the user to configure a pair of a Layer 2 interfaces (trunk ports or port channels) where one
interface is configured to act as a backup to the other. The feature provides an alternative solution to the Spanning Tree
Protocol (STP). Users can disable STP and still retain basic link redundancy. Flexlinks are typically configured in service
provider or enterprise networks where customers do not want to run STP on the device. If the device is running STP, Flexlinks
are not necessary because STP already provides link-level redundancy or backup.
On devices, Flexlink+ can be on the same device or on another device in the stack. When one of the links is up and forwarding
traffic, the other link is in standby mode, ready to begin forwarding traffic if the active link shuts down. If the primary
link shuts down, the standby link starts forwarding traffic. When the active link comes back up, it goes into standby mode
and does not forward traffic.