• Title/Summary/Keyword: CSFQ

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Performance Analysis of a WCSFQ (Weighted Core-Stateless Fair Queueing)-like Space Priority Policy for ATM nodes (ATM 노드를 위한 WCSFQ-유사 공간 우선순위 정책의 성능분석)

  • Kang, Koo-Hong
    • The KIPS Transactions:PartC
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    • v.12C no.5 s.101
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    • pp.687-694
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    • 2005
  • In ATM and W networks, high Priority Packets should be selectively favored over low Priority Packets in case of congestion. For this purpose, we introduce a space priority policy for ATM nodes in this paper which is very similar to the weighted core-stateless fair queueing(WCSFQ) in IP nodes. We also analyze the loss probabilities for different classes of cells for MMPP/D/1/K with a threshold level, and discuss the numerical results. The numerical results illustrate that the WCSFQ scheme can be used to support the differentiated services in ATM or IP nodes.

A Study on Fair Bandwidth Allocation in Core-Stateless Networks: Improved Algorithm and Its Evaluation

  • Kim, Mun-Kyung;Seo, Kyoung-Hyun;Yuk, Dong-Cheol;Park, Seung-Seob
    • Journal of Navigation and Port Research
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    • v.28 no.4
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    • pp.299-303
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    • 2004
  • In the Internet, to guarantee transmission rate and delay and to achieve fair bandwidth allocation, many per-flow scheduling algorithms, such as fair queueing, which have many desirable properties for congestion control, have been proposed and designed. However, algorithms based on per-flow need maintain rate state, buffer management and packet scheduling, so that it cost great deal : implement. Therefore, in this paper, to implement routers cost-effectively, we propose CS-FNE algorithm based on FNE in Core-Stateless network We evaluate CS-FNE comparing with four additional algorithms i.e., CSFQ, FRED, RED and DRR, in several different, configurations and traffic sources. Through simulation results, we show that CS-FNE algorithm can allocate fair bandwidth approximately and is simpler and easier to implement than other per-flow basis queueing mechanisms.

Fair Bandwidth Allocation in Core-Stateless Networks (Core-Stateless망에서의 공정한 대역폭 할당 방식)

  • Kim Mun-Kyung;Park Seung-Seob
    • The KIPS Transactions:PartC
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    • v.12C no.5 s.101
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    • pp.695-700
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    • 2005
  • To provide the fair rate and achieve the fair bandwidth allocation, many per-flow scheduling algorithms have been proposed such as fair queueing algorithm for congestion control. But these algorithms need to maintain the state, manage buffer and schedule packets on a per-flow basis; the complexity of these functions may prevent them from being cost-effectively implemented. In this paper, therefore, to acquire cost-effectively for implementation, we propose a CS-FNE(Core Stateless FNE) algorithm that is based on FM(Flow Number Estimation), and evaluated CS-FNE scheme together with CSFQ(Core Stateless Fair Queueing), FRED(Fair Random Early Detection), RED(Random Early Detection), and DRR(Dynamic Round Robin) in several different configurations and traffic sources. Through the simulation results, we showed that CS-FNE algorithm can allocate fair bandwidth approximately than other algorithms, and CS-FNE is simpler than many per-flow basis queueing mechanisms and it can be easily implemented.

Prevalence of Psychiatric Disorders and Psychosocial Adjustment in Patients with Acquired Immune Deficiency Syndrome(AIDS) (후천성면역결핍증후군(Acquired Immune Deficiency Syndrome ; AIDS) 환자의 정신질환 유병률과 심리사회적 적응)

  • Park, Hwi-Jun;Hong, Jin-Pyo;Woo, Jun-Hee;Ahn, Joon-Ho
    • Anxiety and mood
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    • v.5 no.2
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    • pp.103-111
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    • 2009
  • Objectives : We examined quality of life, psychosocial adjustments to illness, changes in sexual functioning, and prevalence of psychiatric disorders in AIDS patients compared to patients with chronic hepatitis B virus infection (CHB). Methods : Thirty-one men with AIDS and 50 men with CHB were enrolled. The Short-Form 12-Item Health Survey (SF-12), the Psychosocial Adjustment to Illness Scale (PAIS), and the Changes in Sexual Functioning Questionnaire short form (CSFQ-14) were administered. Results on these assessments were compared between the 31 AIDS patients and 50 CHB patients. The Structured Clinical Interview for DSMIV (SCID) was administered to determine the psychiatric diagnosis only for the AIDS patients. Results : The Physical Component Summary score (PCS) was lower in AIDS patients than in CHB patients (p<0.001). In the section examining sexual relationships, AIDS patients exhibited a lower level of adjustment (p<0.05) and had more changes in sexual function (p<0.05) than did CHB patients. Administration of the SCID to AIDS patients indicated that the lifetime prevalence of any psychiatric disorder was 56.7% ; 43.3% for mood disorders, 33.3% for alcohol use disorders, 26.7% for anxiety disorders, and 20% for adjustment disorder. Patients who had experienced any psychiatric disorder had more severe psychosocial distress (p=0.004) and evidenced a lower level of overall psychosocial adjustment (p=0.030) than patients who had not. Conclusion : We showed that AIDS patients have a high prevalence of psychiatric disorders, and that AIDS patients with psychiatric disorders were particularly low in levels of psychosocial adjustment. Thus, careful attention should be given to psychiatric aspects of AIDS patients emphasizing the early diagnosis and treatment of psychiatric disorders.

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A Study of Core-Stateless Mechanism for Fair Bandwidth Allocation (대역 공평성 보장을 위한 Core-Stateless 기법 연구)

  • Kim, Hwa-Suk;Kim, Sang-Ha;Kim, Young-Bu
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.4C
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    • pp.343-355
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    • 2003
  • Fair bandwidth allocations at routers protect adaptive flows from non-adaptive ones and may simplify end-to end congestion control. However, traditional fair bandwidth allocation mechanisms, like Weighted Fair Queueing and Flow Random Early Drop, maintain state, manage buffera and perform packet scheduling on a per-flow basis. These mechanisms are more complex and less scalable than simple FIFO queueing when they are used in the interi or of a high-speed network. Recently, to overcome the implementation complexity problem and address the scalability and robustness, several fair bandwidth allocation mechanisms without per-flow state in the interior routers are proposed. Core-Stateless Fair Queueing and Rainbow Fair Queuing are approximates fair queueing in the core-stateless networks. In this paper, we proposed simple Layered Fair Queueing (SLFQ), another core-stateless mechanism to approximate fair bandwidth allocation without per-flow state. SLFQ use simple layered scheme for packet labeling and has simpler packet dropping algorithm than other core-stateless fair bandwidth allocation mechanisms. We presente simulations and evaluated the performance of SLFQ in comparison to other schemes. We also discussed other are as to which SLFQ is applicable.