Existing edge and core routers in DiffServ networks require an effective scheduling mechanism. In this thesis, we design and implement a DiffServ scheduler on Linux platform to provide QoS for different PHB requirements.
We first modify the PDD model proposed by Dovrolis, and then develop two new scheduling algorithms. The first algorithm is referred to as Priority Queue with Quantum (PQWQ) and the second one is referred to as Average Delay Queue (ADQ). PQWQ can provide lower delay for EF traffic than Deficit Round Robin (DRR), and higher network utilization than Priority Queue (PQ) with EF Token Bucket. In addition, PQWQ can guarantee a minimum bandwidth for AF and Default PHBs and avoid starvation in case of low priority PHBs.
The second scheduler, ADQ, is designed to provide different levels of delay for AF classes. The average delays of the four AF classes can be proportional by adjusting the Delay Differentiation Parameter (DDP). This proportional scheme may allow the higher priority class to send packets more quickly, and therefore achieve higher QoS.
Finally, we implement the two schedulers, PQWQ and ADQ, on Linux platform. We adopt share buffer scheme for AF PHB. Share buffer management can effectively improve the buffer utilization and avoid the unnecessary packet dropping due to the unfair buffer allocation. From the experimental results, we can observe that the new DiffServ schedulers not only provide lower delay and higher bandwidth utilization for EF PHB, but also achieve proportional delay among different AF classes.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0710102-011229 |
| Date | 10 July 2002 |
| Creators | Wu, Wei-Cheng |
| Contributors | Wei-Kuang Lai, Tsang-Ling Sheu, Chung-Ming Huang, Shie-Jue Lee, Ce-Kuen Shieh |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0710102-011229 |
| Rights | campus_withheld, Copyright information available at source archive |
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