Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/8315
標題: ATM 交換器輸入端優先權控制策略之效益模型
Performance Modeling for Two Priority Control Policies for ATM Switches with Input Queueing
作者: 呂育健
Lu, Yu Chien
關鍵字: ATM;非同步傳輸模式;nonblocking packet switch;head-of-line;queueing;push out;partial buffer sharing;非阻隔封包交換器;頭位阻隔;排隊;排擠;部分緩衝器分享
出版社: 電機工程學系
摘要: 
非同步傳輸模式已成為寬頻整體服務數位網路的傳送和交換的機制。交錯非阻隔封包交換器被廣泛應用成為非同步傳輸模式之基本架構。本篇論文研究一具有輸入排隊之非阻隔封包交換器且有兩種不同等級的封包去提供交通流量不同的服務品質要求。兩種輸入排隊方法:排擠和部份緩衝器分享,在這裡被討論。在兩種方法下,高等級和低等級的封包都必須排隊等候服務,而且高等級的封包在輸入端和輸出端都應該比低等級的封包先被處理。在排擠的方法中,只要輸入端的暫存器還沒滿時高等級和低等級的封包都能進入輸入端的暫存器。當暫存器滿的時候,只有高等級封包能排擠掉暫存器的低等級封包進入輸入端的暫存器。在部份緩衝器分享的方法下,當輸入端的暫存器還沒滿的時候高等級封包可以進入輸入端的暫存器,當輸入端暫存器的臨界值還沒滿的時候低等級封包可以進入輸入端的暫存器。為了探討在這兩種方法下的系統效益,我們提出一個近似的兩維馬克夫模型。這篇論文基於一些獨立的假設提供了一個近似的分析而且在每一個輸入端使用一個相等的排隊系統去偵測服務的能力。從這個模型我們可以獲得高等級封包和低等級封包的輸出量、封包遺失機率、排隊長度分佈。我們用模擬來驗證這些結果。

Asynchronous Transfer Mode (ATM) has been adopted as the transport and switching mechanism for B-ISDN. Crossbar nonblocking packet switches are widely used as the fundamental architecture for ATM switch. This thesis studies an N N nonblocking packet switch with input queues and two priority classes of cells which can be used to support traffic with different QoS requirements. Two queueing policies (push out and partition buffer sharing) are studied here. Under both policies, packets of high priority and low priority classes are queued when waiting for service, and high priority packets prevail over low priority packets at the inputs as well as the outputs. In the push out policy, high priority packets and low priority packets can enter the input buffer when the input buffer is not full. When the input buffer is full, only high priority packets can enter the queue by forcing out low priority packets in the queue. In the partition buffer sharing policy, high priority packets can enter the input buffer when the input buffer is not full. Low priority packets can enter the input buffer when the current occupancy of input buffer has not reached a pre-specified threshold. An approximate two-dimensional Markov-chain model is developed for studying the performance under both policies, based on some independence assumptions and by using an equivalent queueing system to estimate the services capability seen by each input. From this model, we obtain the throughput, packet drop probability, and queue length distribution of high priority and low priority packets. The results are verified with simulation.
URI: http://hdl.handle.net/11455/8315
Appears in Collections:電機工程學系所

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