Joint buffer management and scheduling for input queued switches

Input queued (IQ) switches are highly scalable and they have been the focus of many studies from academia and industry. Many scheduling algorithms have been proposed for IQ switches. However, they do not consider the buffer space requirement inside an IQ switch that may render the scheduling algorithms inefficient in practical applications. In this dissertation, the Queue Length Proportional (QLP) algorithm is proposed for IQ switches. QLP considers both the buffer management and the scheduling mechanism to obtain the optimal allocation region for both bandwidth and buffer space according to real traffic load. In addition, this dissertation introduces the Queue Proportional Fairness (QPF) criterion, which employs the cell loss ratio as the fairness metric. The research in this dissertation will show that the utilization of network resources will be improved significantly with QPF. Furthermore, to support diverse Quality of Service (QoS) requirements of heterogeneous and bursty traffic, the Weighted Minmax algorithm (WMinmax) is proposed to efficiently and dynamically allocate network resources. Lastly, to support traffic with multiple priorities and also to handle the decouple problem in practice, this dissertation introduces the multiple dimension scheduling algorithm which aims to find the optimal scheduling region in the multiple Euclidean space

Weighted round robin scheduling in input-queued packet switches subject to deadline constraints

Ankara : Department of Electrical and Electronics Engineering and the Institute of Engineering and Science of Bilkent Univ., 2000.Thesis (Master's) -- Bilkent University, 2000.Includes bibliographical references leaves 59-63In this thesis work, the problem of scheduling deadline constrained traffic is studied. The problem is explored in terms of Weighted Round Robin (WRR) service discipline in input queued packet switches. Application of the problem may arise in packet switching networks and Satellite-Switched Time Division Multiple Access (SS/TDMA) systems. A new formulation of the problem is presented. The main contribution of the thesis is a ’’backward extraction” technique to schedule packet forwarding through the switch fabric. A number of heuristic algorithms, each based on backward extraction, are proposed, and their performances are studied via simulation. Numerical results show that the algorithms perform significantly better than earlier proposed algorithms. The experimental results strongly assert Philp and Liu conjecture.Rai, Idris AM.S

Deadline-ordered burst-based parallel scheduling strategy for IP-over-ATM with QoS support.

Siu Chun.Thesis (M.Phil.)--Chinese University of Hong Kong, 2001.Includes bibliographical references (leaves 66-68).Abstracts in English and Chinese.Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Thesis Overview --- p.3Chapter 2 --- Background and Related work --- p.4Chapter 2.1 --- Emergence of IP-over-ATM --- p.4Chapter 2.2 --- ATM architecture --- p.5Chapter 2.3 --- Scheduling issues in output-queued switch --- p.6Chapter 2.4 --- Scheduling issues in input-queued switch --- p.18Chapter 3 --- The Deadline-ordered Burst-based Parallel Scheduling Strategy --- p.23Chapter 3.1 --- Introduction --- p.23Chapter 3.2 --- Switch and queueing model --- p.24Chapter 3.2.1 --- Switch model --- p.24Chapter 3.2.2 --- Queueing model --- p.25Chapter 3.3 --- The DBPS Strategy --- p.26Chapter 3.3.1 --- Motivation --- p.26Chapter 3.3.2 --- Strategy --- p.31Chapter 3.4 --- The Deadline-ordered Burst-based Parallel Iterative Matching --- p.33Chapter 3.4.1 --- Algorithm --- p.34Chapter 3.4.2 --- An example of DBPIM --- p.35Chapter 3.5 --- Simulation results --- p.33Chapter 3.6 --- Discussions --- p.46Chapter 3.7 --- Future work --- p.47Chapter 4 --- The Quasi-static DBPIM Algorithm --- p.50Chapter 4.1 --- Introduction --- p.50Chapter 4.2 --- Quasi-static path scheduling principle --- p.51Chapter 4.3 --- Quasi-static DBPIM algorithm --- p.56Chapter 4.4 --- An example of Quasi-static DBPIM --- p.59Chapter 5 --- Conclusion --- p.63Bibliography --- p.6

Dynamic Window-Constrained Scheduling for Real-Time Media Streaming

This paper describes an algorithm for scheduling packets in real-time multimedia data streams. Common to these classes of data streams are service constraints in terms of bandwidth and delay. However, it is typical for real-time multimedia streams to tolerate bounded delay variations and, in some cases, finite losses of packets. We have therefore developed a scheduling algorithm that assumes streams have window-constraints on groups of consecutive packet deadlines. A window-constraint defines the number of packet deadlines that can be missed in a window of deadlines for consecutive packets in a stream. Our algorithm, called Dynamic Window-Constrained Scheduling (DWCS), attempts to guarantee no more than x out of a window of y deadlines are missed for consecutive packets in real-time and multimedia streams. Using DWCS, the delay of service to real-time streams is bounded even when the scheduler is overloaded. Moreover, DWCS is capable of ensuring independent delay bounds on streams, while at the same time guaranteeing minimum bandwidth utilizations over tunable and finite windows of time. We show the conditions under which the total demand for link bandwidth by a set of real-time (i.e., window-constrained) streams can exceed 100% and still ensure all window-constraints are met. In fact, we show how it is possible to guarantee worst-case per-stream bandwidth and delay constraints while utilizing all available link capacity. Finally, we show how best-effort packets can be serviced with fast response time, in the presence of window-constrained traffic

A Linux Real-Time Packet Scheduler for Reliable Static SDN Routing

In a distributed computing environment, guaranteeing the hard deadline for real-time messages is essential to ensure schedulability of real-time tasks. Since capabilities of the shared resources for transmission are limited, e.g., the buffer size is limited on network devices, it becomes a challenge to design an effective and feasible resource sharing policy based on both the demand of real-time packet transmissions and the limitation of resource capabilities. We address this challenge in two cooperative mechanisms. First, we design a static routing algorithm to find forwarding paths for packets to guarantee their hard deadlines. The routing algorithm employs a validation-based backtracking procedure capable of deriving the demand of a set of real-time packets on each shared network device, and it checks whether this demand can be met on the device. Second, we design a packet scheduler that runs on network devices to transmit messages according to our routing requirements. We implement these mechanisms on virtual software-defined network (SDN) switches and evaluate them on real hardware in a local cluster to demonstrate the feasibility and effectiveness of our routing algorithm and packet scheduler