switched network backup (SNBU)

1. An optional facility that allows a user to specify, for certain types of physical units, a switched line to be used as an alternate path if the primary line becomes unavailable or unusable.; 一種可供用戶任選的設施,允許用戶在主線路已被占用或不能使用時,給某些類型的物理裝置指定一條交換線路作為其替換通路。 2. In communications, an optional facility enabling a user to specify an alternative path if the primary path is, for some reason, not available. | 在通信技術中,當因某種原因不能占用主通路時,使用戶能指定另一條替換通路的任選設施。