The on boot link override feature adds support for keeping interfaces down at switch boot until the correct interface state can be determined by feature agents. Keeping the interfaces down through device boot will protect against transient traffic loss by preventing downstream peers from detecting a transient interface up and sending traffic to the device. 

If a gNMI.Set union_replace operation or gNOI.BootConfig RPC is issued without this configuration, an error is returned to the client.This feature adds support for the following to OpenConfig: gNMI.Set union_replace operation