對於網路速度的要求，我們越來越依賴於光纖網路及光交換機。由於缺乏光隨機儲存記憶體，傳統上只能利用電子記憶體，例如：隨機存取記憶體，來建造隊伍。雖然，電子隨機存取記憶體非常便宜，然而要將光封包轉換成電子訊號來儲存；再將電子訊號轉成光封包來傳輸，一方面顯得不經濟，另一方面也拖慢了傳輸速度。這就是我們一般所稱的光-電(O-E)及電-光(E-O)轉換的瓶頸。使用交換機延遲線，我們可以建構出最基本的光儲存元件。利用交換機延遲線如何建造低複雜度的光儲存隊伍就變成了很重要的研究題目。
排隊理論一般而言是用來分析隊伍的效能。在這篇論文之中，我們對於排隊理論的另一方面感到興趣，那就是：如何來建造一個隊伍。我們考慮了三種離散時間的隊伍：線性壓縮器、非超前延遲線及彈性延遲線。這三種隊伍可以對應於交換機理論的條件非阻擋交換機及〈嚴格〉非阻擋交換機。相似於他們在交換機理論上的對應，這三種隊伍也存在多層的建造方式。具體的說，我們發展了兩層結構的線性壓縮器。然而，在非超前延遲線及彈性延遲線中，我們發展了三層的結構。除此以外，也能利用階層的Cantor網路來建構彈性延遲線。至於這些隊伍的應用，我們指出了兩種可以完全仿真輸出緩衝儲存交換機的光封包交換機架構。

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