Sticking with our mail example, if there’s a blizzard in Minneapolis grinding things to a halt, the Chicago mail hub can decide to route the letter through Omaha instead.

继续我们的邮件示例，如果明尼阿波利斯的暴风雪使一切陷入停顿，芝加哥邮件中心可以决定将信件转交给奥马哈。