Title page for etd-0813103-203113


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URN etd-0813103-203113
Author Yi-Min Shiu
Author's Email Address kaine@atm.ee.nsysu.edu.tw
Statistics This thesis had been viewed 4660 times. Download 5204 times.
Department Electrical Engineering
Year 2002
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title A Jitter Minimization Mechanism with Credit/Deficit Adjustment in IPv6-Based DiffServ Networks
Date of Defense 2003-07-24
Page Count 58
Keyword
  • Jitter
  • IPv6
  • DiffServ
  • Packet Scheduling
  • WFQ
  • DSCP Adjustment
  • Linux
  • Abstract  In a DiffServ networks, edge and core router classify traffic flows into different PHBs and provide different QoS for the classified flows. In order to achieve satisfactory QoS guarantee, many packet schedulers were proposed. However IETF have not formally standardized an appropriate and effective packet scheduler to minimize the jitter for real-time traffic.
     In RFC, EF flows are characterized with low-latency, low packet loss rate, and low jitter. Therefore, real-time traffic is often classified into EF flow. By considering the characteristics of real-time traffic, it is not appropriate to forward packets either too fast or too slow. Hence, in this Thesis, we propose a mechanism in which each packet is attached with its own per-hop queuing delay. If a packet is forwarded within its own per-hop queuing delay, we say the packet may arrive too early (credit accumulation). If a packet is forwarded beyond its own per-hop queuing delay, we say the packet has late arrival (deficit accumulation). The Credit/Deficit information can be stored in the IPv6 optional header so that it can pass through the whole networks. If we can minimize the Credit/Deficit, the jitter can be minimized too. Our design is based on a modified WFQ by adding functions such as estimated queuing delay and dynamic class changes. The dynamic class changes allow EF packets to switch among queues to achieve lower jitter and constant delay.
     We first implement the traditional WFQ scheduler on Linux platform and then followed by the implementation of the Credit/Deficit WFQ (CDWFQ). The experimental results have shown that CDWFQ can provide nearly constant queuing delay, lower packet loss rate, and lower jitter for EF traffic flows.
    Advisory Committee
  • Cheng-Shong Wu - chair
  • Yuan-Sun Chu - co-chair
  • Shie-Jue Lee - co-chair
  • Chun-Hung Lin - co-chair
  • Tsang-Ling Sheu - advisor
  • Files
  • etd-0813103-203113.pdf
  • indicate access worldwide
    Date of Submission 2003-08-13

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