一個提供比例式延遲差異服務的封包排程演算法

Abstract

由於網際網路的普及，提供需要較高頻寬和及時性的服務是愈來愈迫切．然而現今網際 網路架構的best-effort特性使得提供這類服務的想法變得不可能．Devrolis提出了一個 相對的差別服務架構，在這個架構下使用了比較簡單和粗略的方式來提供差別服務． 基於這個相對的差別服務架構，我們提出了一個封包排程的機制，叫做AJP排程器，這個 排程器可以在不同的類別之中針對封包延遲的差異(jitter)提供成比例的差別服務． 模擬實驗的結果顯示我們所設計的排程器的確符合其設計的目標，也就是對於長時間的 封包延遲差異和短時間的封包延遲差異，排程器都能對於不同的競爭類別提供成比例的 差別服務．網路的管理人員可以直接透過設定差別服務係數來調整不同類別之間所獲得 服務的等級差距．將AJP排程器整合進網際網路之後，提供互動式的語音服務就變得可 行了．

For the popularity of the Internet, more high-bandwith and real-time services are needed. The best-effor natural of current Internet architecture makes it impossible to provide such services. Dovrolis proposed the relative differentiated service architecture, which provides service differentiation in a simpler and coarse way. Following this architecture, we propose a packet scheduling mechanism, called AJP scheduler, which provides the proportional jitter differentiation between the competing classes. Simulation results show that the AJP scheduler does acheive its design goal, i.e. providing proportional jitter differentiation between the competing classes in terms of long-term average jitter and short-term average jitter. Network operator can adjust the service level spacing by simply setting the service differentiation parameters. Deploying the AJP scheduler in the Internet will make it possible for providing interactive voice services.