應用封包延遲指示器於差別性服務等候機制之研究

A Study on a Differentiated Service Queuing Scheme with a Packet Delay Indicator

傅振華(Chen-Hua Fu) ； 楊千慧(Chian-Huei Yang)

《國防管理學報》 36卷2期 (2015/11) Pp. 59-74

摘要

過去傳統網路因單純及少量的資料傳送就可滿足許多人之需求，而現今卻因科技技術過於蓬勃發展，頻寬資源、供不應求，導致網路效能不佳。然而對於服務品質（Quality of Service, QoS）之需求則是愈來愈講究，因此網路頻寬資源的管理及網路資源的充分利用成為服務提供者重視的議題。為充分利用網路資源，應當將網路應用依照其重要性分為不同等級而傳送，進而提升網路效能及降少雍塞之情況。本研究在差別性服務網路環境下，應用RED與視窗量測運作機制的概念，針對網路間道器提出一個差別性服務等候機制應用封包延遲指示器進行網路流量控制，期望藉由各個網路應用封包傳送優先等級做為閘道器傳輸封包的考量依據，使得其高優先權限的網路應用封包能夠優先獲得進入閘道器等候機制邏輯佇列空間，並能夠優先從佇列空間中傳送至下一個網路節點，使得網路能夠依據三大類型網路應用之特性提供差別性服務。本研究嘗試瞭解以封包傳送延遲為基之差別性服務等候機制運作在不同的網路應用封包長度需求與封包間平均傳送時間差的模擬想定下，可使其較高傳輸優先權限的網路應用獲得較好的封包傳輸效能，而達到差別性服務成效。

關鍵字

差別性服務等候機制 ； 封包延遲 ； 服務品質 ； 封包允入機制

並列摘要

Due to network bandwidth can not fully satisfy all IP applications QoS requirements of IP applications are different, a differentiated service scheme might use to satisfy QoS requirements of different feature IP applications. This study proposes a differentiated-service queueing scheme with packet delay indicators within an internet gateway to handle traffic flows over a network. The proposed queueing scheme bases on packet transmission priorities of IP applications to handle IP packet forwarding process. In the proposed scheme, three logical queueing buffers are used to store arrival IP packets with three different packet transmission priorities; the packet enqueueing module is a RED-alike function to enqueue IP packets into their logical queueing buffer; and the packet dequeueing module is a WRR function to dequeue IP packet from the logical queueing buffer. Morerover, the proposed queueing bases on average packet delay of the same packet transmission priority packets set their corresponding packet admission indicators. A source node will depend on the packet admission indicators to determine whether an application flow can send its IP packets or not. This study adopts simulation method to understand packet forwarding performance of the proposed queueing scheme. NS2 is used as the simulation platform; the proposed scheme is implemented with C++ and integrated in NS2. After several scenarios simulated, the simulation results show that the proposed queueing scheme can base on packet forwarding priorities to support differentiated packet forwarding services among IP applications. Moreover, with the packet admission indicator operating, packet forwarding performance of IP applications can be enhanced.

並列關鍵字

Differentiated service queueing scheme ； Packet delay ； QoS ； Packet admission measure