Good evening

Unfortunately, the Man Page: https://netplan.io/reference is not precise in the description for the optional (bool) property.

If one interface has this setting:

    optional: true 

and the Interface gets online some time after the boot sequence, does networkd initialize it as soon as it detects the Interface?

I ask how it is designed/meant to be and not how a specific OS Version implements it :-)

Thanks a lot for any help!

2 Answers 2


Without the optional: true statement, ethernet network interfaces that are not completely ready can add an additional 2+ minutes to the boot time.

With the optional: true statement, the boot cycle will continue, without delay, and it'll bring up the ethernet network interfaces when they're ready.

Unless you've got a specific ethernet network interface that MUST be completely operational for other services to properly start, go ahead and add this statement to the other ethernet interface stanzas.


Yes, it does. optional interfaces are treated the same as any other interface by networkd, they just don't block the boot.


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