# Using standby NetLinks for high availability in outbound traffic management

Standby NetLinks allow you to define a NetLink as a backup that is only activated when all primary NetLinks are unavailable. Using standby NetLinks minimizes the use of NetLinks that are more expensive or otherwise less preferable, while still ensuring the high availability of Internet connectivity.

To test which NetLinks are available, the status of the NetLinks is monitored. As soon as one or more primary NetLinks become active again, the standby NetLinks are deactivated. The deactivated NetLink still handles the previously established connections, but new connections are no longer sent to the standby NetLink. You can define multiple active and standby NetLinks.

Note: You must configure probing settings for each NetLink when you use active and standby NetLinks.

When load balancing is used with standby NetLinks, traffic is only distributed between the NetLinks that are currently active. Standby NetLinks are only activated when failure is detected, not to balance the load.

Using standby NetLinks on the same interface as other NetLinks affects the interface speed you enter in the configuration of QoS for engine interfaces.