In a communications network, which may be a broadband optical network, a packet is transmitted from a source node to a destination node on a looped signal path. A return signal, which may function as an acknowledgement of the original signal, is transmitted back to the source node from the destination...http://www.google.com.tw/patents/US6731648?utm_source=gb-gplus-share專利 US6731648 - Method and apparatus for transmitting a return signal in a loop network
