Towards Programmable Packet Scheduling

Packet switching remains one of the bottlenecks in building fast Internet routers. Load balancing and switch scheduling are two important algorithms in the effort to maximize the throughput and minimize the latency of these packet switches. A load balancing algorithm regulates the traffic to conform to the service rates while a switch scheduling algorithm allocates the service rates adaptive to the arrival patterns. Many existing load balancing and switch scheduling algorithms are very similar. We show that load balancing and switch scheduling systems are dual systems based on the linear queue dynamics approximation. This allows us to cast a load balancing problem as a scheduling problem, and vice versa. We further show an example of designing a new algorithm for load balancing using an existing scheduling algorithm based on the duality. The duality perspective also allows us to solve unknown problems. We find the entropy rate of the randomized bandwidth allocation system with linear queue dynamics based on the knowledge of the entropy rate of the randomized load balancing system. For the general case, we find both an upper and a lower bound on the entropy rate. The joint use of dual load balancing and switch scheduling algorithms leads to performance gains as we show using mean field analysis.

We consider the problem of dynamic bandwidth allocation (DBA) for Ethernet passive optical networks (EPONs), subject to requirements of fairness, efficiency, and cost. The traffic from the access side is aggregated at ONUs and mapped to different classes of service queues. We employ credit pooling technique, together with weighted-share policy, that enables the OLT to partition the upstream bandwidth among different classes, and to prevent ONUs from monopolizing the bandwidth. We propose a packet scheduling algorithm, referred to as COPS (Class-of-service Oriented Packet Scheduling) that meets our requirements set out above. We compare COPS with a well-known scheduling algorithm which employed a standard priority-based scheduling, and we show that COPS is superior in terms of network utilization and maximum packet delay.

We propose two almost-all optical packet switch architectures, called the packing switch and the scheduling switch, which when combined with appropriate wait-for-reservation or tell-and-go connection and flow control protocols provide lossless communication for traffic that satisfies certain smoothness properties. Both switch architectures preserve the order of packets that use a given input-output pair, and are consistent with virtual circuit switching. We find a lower bound on the number of elementary (2-state) switches required by any switch architecture to meet the objectives we have set. The number of 2-state switches used in the scheduling switch is of the optimal order jointly with respect to the number of inputs and with respect to the burstiness of the traffic streams (as measured by an appropriate parameter). The packing switch requires very little processing of the packet header, and uses a number of 2-state switches that is of the optimal order in terms of the burstiness parameter. We also examine the suitability of the proposed switches for the design of circuit switched networks. We find that the scheduling switch combines low hardware cost with little processing requirements at the nodes, and is an attractive architecture for both packet switched and circuit switched high-speed networks.

LTE-Advanced offers significantly higher data rates than the legacy system. The carrier aggregation (CA) technology allows scalable expansion of effective bandwidth provided to user equipment (UE) through simultaneous utilization of radio resources across multi-component carriers. In this paper we propose a new packet scheduling (PS) criterion algorithm that satisfies the fairness among the different kinds of UEs by designing a weighting factor to proportional fair (PF) packet scheduling (PS) algorithms, while enhancing their throughput performance. The proposed PS algorithm is implemented and validated in a PS module for LTE/LTE-Advanced via system level simulations. Results show that PS-enhanced algorithm achieve higher throughput for both LTE and LTE-Advanced UEs.

Packet parsing is the first step in processing of packets in devices such as network switches and routers. The process of packet parsing has become more challenging due to the increase in line rates and emergence of Software Defined Networking which leads to new protocols being adopted. In this paper, we present a novel architecture for parsing of packets. The architecture is fully programmable and is not tied to any specific protocol. It can be programmed to parse any protocol making it suitable for Software Defined Networks. Compared with the parser used in the Reconfigurable Match Tables, our parser improves supported throughput by a factor of 3.2. Moreover, to achieve the target throughput of 640 Gbps, our parser needs only 2 percent of the number of gates used in the parsers of Reconfigurable Match Tables.

Long Term Evolution (LTE) network deploys Orthogonal Frequency Division Multiple Access (OFDMA) technology for downlink multi-carrier transmission. To meet the Quality of Service (QoS) requirements for LTE networks, packet scheduling has been employed. Packet scheduling determines when and how the user’s packets are transmitted to the receiver. Therefore effective design of packet scheduling algorithm is an important discussion. The aims of packet scheduling are maximizing system throughput, guaranteeing fairness among users, andminimizing either or both PacketLoss Ratio (PLR)and packet delay. Inthis paper, the performance of two packet scheduling algorithms namely Log Maximum-Largest Weighted Delay First (LOG-MLWDF) and Max Delay Unit (MDU), developed for OFDM(Orthogonal Frequency Division Multiplexing)networks, has been investigated in LTE downlink networks, and acomparison of those algorithmswith a well-known scheduling algorithm namely Maximum-Largest Weighted Delay First(MLWDF) has been studied.The performance evaluation was in terms of system throughput, PLR and fairness index. This study was performed forboth real time (voice and video streaming)and non-real time (best effort)perspectives. Results show that for streaming flows,LOG-MLWDF shows best PLR performance among the considered scheduling schemes, and for best effort flows, it outperforms theother two algorithms in terms of packet delay and throughput.

With the advent of multi-core computer systems, real-time (RT) scheduling on multiprocessors (MPs) is gaining more and more practical relevance. Basic algorithms developed in the 1970s or earlier are strongly influential on state-of-the-art preemptive hard real-time scheduling algorithms. These relationships will be revealed and visualized by four genealogies. Here, the two classification dimensions prioritization dynamics and migration dynamics serve as a framework for the systematization. Finally, such genealogical reconstructions could even lead to the discovery of new algorithms. An extra look will be devoted to the group of fully dynamic scheduling algorithms with full migration in which algorithms can reach full utilization, neglecting scheduling and context switching overheads. The important question for a set of RT scheduling algorithms serving as a basis for more sophisticated ones will be dealt with.

Packet scheduling constitutes the core problem in efficient fair allocation of bandwidth to competing flows. To date, numerous algorithms for packet scheduling have been suggested and tested. However, only a few of them are currently deployed. One of the key reasons for rarity of applied packet scheduling methods lies in the complexity of their implementation. This paper describes a family of randomized algorithms for packet scheduling. These algorithms are simple to implement and require small amounts of computation time. Specifically we present an O(1) probabilistic weighted fair queuing algorithm that emits packets from flows with an improved delay jitter. Experimental results of the proposed randomized algorithms suggest that the randomized approach is a viable alternative to the currently deployed deterministic fair queuing algorithms.

This work investigates which algorithm of scheduling algorithm will provide the best QoS for which type of application in addition to how stationary nodes and mobile nodes affect the network in terms of mobility and time. We used variable scheduling algorithms Weighted Fair Queuing (WFQ), Priority Queuing (PQ),First In First Out (FIFO) for different applications including real-time and non-real-time, in the context of mobility and stationery to investigate which algorithm of scheduling will provide the best quality of service with presenting a HetNet based LTE-A architecture including macrocell, picocells and femtocells.

When single Field-Programmable Gate Array(FPGA) deals with the huge amounts of data in high-speed network,low efficiency problem occurs.According to dual priority schedule algorithm for multi-processor and high-speed data acquisition and processing model based on multi-FPGA,a dual priority dynamic scheduling algorithm was proposed based on multi-FPGA.For strong real-time periodic tasks set in low priority queue,the Earliest Deadline Critical Laxity(EDCL) scheduling algorithm was given to determine the priority of task according to the degree of relaxation of the tasks.If the task was not finished when the promotion time was up,it would be promoted to high priority queue.For soft real-time periodic tasks,an algorithm was put forward to assign the tasks to middle priority queue and schedule them by delaying the deadline of tasks to dynamic blur threshold.The experimental results show that the proposed algorithms can well schedule strong real-time periodic tasks and guarantee the priority execution of important tasks,and it can also reduce miss rate of soft real-time periodic tasks caused by preemption.

In this paper, an analysis of priority queuing and scheduling algorithms is presented. The algorithms utilised in the analysis include First in First out, Priority Queuing, and Weighted Fair Queuing. The analysis network includes a video server and client, an FTP server and client, a VoIP system and a HTTP server and client. The traffic pattern and the packet sizes in the various applications were evenly distributed and based on Poisson's Distribution Function. The Markov model implemented utilised the packet arrival rate and the service time as variables and calculated the average waiting time and the length of the queues. The traffic from this network was routed across a link between two routers which were configured to support the applications based on the queuing algorithms. The end to end delay and the packet drop characteristics of each of these queuing models was compared for the simulated network.

In this paper, a hybrid spatial and temporal scheduling algorithm for wireless networked control system, which takes the distance between robot and task region as well as the deadline of a task into consideration is proposed. In our method, we quantify spatial and temporal factors for eventually getting the priority queue. Based on the priority queue, the robot is able to execute the tasks sequentially. At last, extensive simulations are conducted to show the advantages of our spatial and temporal scheduling algorithm. Simulation results show that, on the premise of ensuring high successful scheduling rate, compared with previous method, our scheme show merits in terms of task requesting throughput, successful task solving ratio, average responding delay.

Long Term Evolution(LTE) 시스템은 멀티미디어 서비스와 같은 다양한 서비스를 이동 사용자에게 제공할 수 있다. 실제로 HSPA+(High Speed Packet Access plus)는 다운링크의 비트 율(bit rate)을 크게 향상 시켰으나, 다양한 멀티미디어 서비스에서 요구하는 서비스 품질을 어떻게 만족시킬 것인가에 대한 연구는 매우 미비한 상태이다. 본 논문에서는 proportional fair(PF) 알고리즘을 기반으로 하여 LTE를 위한 효율적인 패킷 스케쥴링 알고리즘을 제안하였다. 제안된 알고리즘에서는 패킷 스케쥴링을 할 때 패킷의 우선순위를 결정하는 가장 중요한 요소인 트래픽 클래스의 가중치와 순간 사용자 데이터 전송율을 최적화 하였다. 또한 다중 셀(multi-cell) 환경에서 LTE를 통해서 사용자에게 전송되는 멀티미디어 트래픽을 시뮬레이션 함으로써 제안된 알고리즘의 성능이 향상되었음을 보였다. The Long Term Evolution (LTE) system is already able to provide a background of variety services for mobile users with multimedia services such as audio, video, and data. In fact, the High Speed Packet Access plus (HSPA+) solution can greatly enhance bit rates on down-link. However, the supporting for multimedia applications with different QoS (Quality of Service) requirements is not devised yet. Hence, in this paper we propose an effective packet scheduling algorithm based on Proportional Fairness (PF) scheduling algorithms for the LTE. In this proposed packet scheduling scheme, we optimized instantaneous user data rates and the traffic class weight which prioritize user's packets. Finally, we evaluated and showed the performance of the proposed scheduling algorithm through simulations of multimedia traffics being transmitted to users over LTE links in a multi-cell environment.

Only best-effort traffic was supported by traditional packet switching networks, but newer applications need network services that allow an end-client to transport data with performance guarantees. The choice of packet-scheduling algorithm used at switching nodes is crucial in providing Quality of Service (QoS). This paper proposes a downlink packet scheduling algorithm for QoS provisioning in High Speed Downlink Packet Access (HSDPA) based UMTS networks. In HSDPA, a single logical channel is shared amongst multiple contending users. Besides better link utilization, scheduling disciplines seek to achieve fair allocation of this shared resource. However, these two criteria can potentially be in conflict. The scheduling algorithm proposed in this paper, Wireless Fair High Speed Scheduling, addresses this conflict. The basic idea is to allocate the wireless channel fairly amongst users, even during short time scales, according to their data rate requirements. Simulation results show that the proposed scheduling algorithm provides better link utilization, as well as long-term and short-term fairness amongst users, even under heavy load conditions.

With the applications of Internet of Things (IoT) for smart cities, the real-time performance for a large number of network packets is facing serious challenge. Thus, how to improve the emergency response has become a critical issue. However, traditional packet scheduling algorithms cannot meet the requirements of the large-scale IoT system for smart cities. To address this shortcoming, this paper proposes EARS, an efficient data-emergency-aware packet scheduling scheme for smart cities. EARS describes the packet emergency information with the packet priority and deadline. Each source node informs the destination node of the packet emergency information before sending the packets. The destination node determines the packet scheduling sequence and processing sequence according to emergency information. Moreover, this paper compares EARS with a first-come, first-served, multilevel queue algorithm and a dynamic multilevel priority packet scheduling algorithm. Simulation results show that EARS outperforms these previous scheduling algorithms in terms of packet loss rate, average packet waiting time, and average packet end-to-end delay.