Operational and performance issues of a CBQ router

Risso, Fulvio; Gevros, Panos

doi:10.1145/505696.505702

Cited by 18 publications

(12 citation statements)

References 6 publications

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“…Class-based WFQ (CBWFQ) extends the standard WFQ [1] functionality to provide support for user defined traffic classes. It also extends the packet round robin (PRR) in [37] and weighted round robin (WRR) in [38]. In [39], Millet and Mammeri derived the delay bound of a packet belonging to a regulated (r p i , ) flow and assigned the highest priority in CBWFQ network, where r represents the link capacity and p i the fraction of the link bandwidth that determines the amount of bandwidth reserved for class i.…”

Section: Class-based Queuingmentioning

confidence: 99%

Expedited forwarding end‐to‐end delay and jitter in DiffServ

Alshaer

Elmirghani

2008

Int J Communication

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SUMMARYThe scheduling disciplines and active buffer management represent the main components employed in the differentiated services (DiffServ) data plane, which provide qualitative per-hop behaviors corresponding to the QoS required by supported traffic classes. In the first part of this paper, we compute the per-hop delay bound that should be guaranteed by the different multiservice scheduling disciplines, so that the end-to-end (e2e) delay required by expedited forwarding (EF) traffic can be guaranteed. Consequently, we derive the e2e delay bound of EF traffic served by priority queuing-weighted fair queuing (PQ-WFQ) at every hop along its routing path. Although real-time flows are principally offered EF service class, some simulations on DiffServ-enabled network show that these flows suffer from delay jitter and they are negatively impacted by lower priority traffic. In the second part of this paper, we clarify the passive impact of delay jitter on EF traffic, where EF flows are represented by renewal periodic ON-OFF flows, and the background (BG) flows are characterized by the Poisson process. We analyze through different scenarios the jitter effects of these BG flows on EF flow patterns when they are served by a single class scheduling discipline, such as first-input first-output, and a multiclass or multiservice scheduling discipline, such as static priority service discipline. As a result, we have found out that the EF per-hop behaviors (PHBs) configuration according to RFCs 2598 and 3246 (IETF RFC 2598, June 1999 RFC 3246, IETF, March 2002) cannot stand alone in guaranteeing the delay jitter required by EF flows . Therefore, playout buffers must be added to DiffServ-enabled networks for handling delay jitter problem that suffers from EF flows.

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Section: Class-based Queuingmentioning

confidence: 99%

Expedited forwarding end‐to‐end delay and jitter in DiffServ

Alshaer

Elmirghani

2008

Int J Communication

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“…For example, Class A queue may get 60% of link BW, Class B 30% and Class C 10% as shown inFigure 5.3. Some of the link sharing and scheduling algorithms include Class-Based Queuing[14],[20], Hierarchical-Fair Service Curve Algorithm[23],[21]. By allowing isolation between realtime and best effort traffic in cooperation with packet schedulingalgorithms that give priority to the real-time traffic, controlled link-sharing is a key component in enabling deployment of priority based packet scheduling algorithms designed to meet the end-to-end service requirements of real time traffic.…”

mentioning

confidence: 99%

Cooperative congestion control in power grid communication networks

Cherukuri

Nahrstedt

2011

2011 IEEE International Conference on Smart Grid Communications (SmartGridComm)

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Power Grid Digital Communication networks are needed for the delivery of Phasor Measurement Unit (PMU)[1] sensor data with real time guarantees to the control centers for timely decisions. Present day network systems are unable to ensure the real-time needs of the PMU data as they are not designed to support PMU devices. Hence, the need arises for new communication and control protocols. This thesis describes the Cooperative Congestion Control framework to ensure real-time guarantees for PMU data and to respond if transient deviations in real-time PMU network traffic occur. The framework utilizes a) NASPI[3], [4] aligned multiple service class queuing architecture; b) Cooperative real-time flow scheduling and Bandwidth reassignment; c) Cooperative coordination and back-pressure among neighboring nodes. It then yields real-time PMU data guarantees during transient traffic pattern changes and/or overload situations. Our experiments confirm that the framework delivers real-time performance very well under different transient scenarios.

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“…The most common CBQ implementations 3 can be found in the ns-2 simulator and ALTQ tool, although both of them present some discrepancies from the original specification (some have been pointed out in [3]). However an in-depth analysis of the CBQ behavior shows some weakness that will be briefly pointed out.…”

Section: Cbq: An In-depth Analysismentioning

confidence: 99%

Decoupling bandwidth and delay properties in class based queuing

Risso

Proceedings. Sixth IEEE Symposium on Computers and Communications

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This paper presents the Decoupled Class Based Scheduling, a CBQ-derived scheduling algorithm. Main advantages of D-CBQ are a new set of rules for distributing excess bandwidth and the ability to guarantee bandwidth and delay in a separate way, whence the name "decoupled"; moreover D-CBQ guarantees better delay bounds and more precise bandwidth assignment. This paper presents D-CBQ main points and discusses the choices for the implementation of the algorithm.

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Operational and performance issues of a CBQ router

Cited by 18 publications

References 6 publications

Expedited forwarding end‐to‐end delay and jitter in DiffServ

Expedited forwarding end‐to‐end delay and jitter in DiffServ

Cooperative congestion control in power grid communication networks

Decoupling bandwidth and delay properties in class based queuing

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