In this paper, a design alternative for guaranteeing short-term QoS in the E-PON (Ethernet-Passive Optical Network) OLT (Optical Line Terminal) node is studied. A scheduling algorithm called Short-term QoS Deficit Round Robin (SQ-DRR) is proposed to guarantee tunable deterministic QoS constraints for multimedia applications over E-PON. The major appealing aspect of the scheduler is that it guarantees delay constraint for short-term aggregate burst traffic violating pre-contracted descriptors at the same time without loosing long-term fairness. We then evaluate the scheduler performance with and without admission control scheme under non-stationary long-range dependence (LRD) traffic. The simulation results indicate that the SQ-DRR performs well in dynamic burst traffic conditions.

A fast class-of-service oriented packet scheduling (FCOPS) has a service fairness problem since a credit pool for a service class is initialized at the beginning of a transmission cycle whose starting moment is fixed at a specific ONU. To remedy the service unfairness of FCOPS, we suggest an enhanced class-of-service oriented packet scheduling (ECOPS) that uses a new initialization cycle whose starting moment is fairly distributed to each ONU. Also, ECOPS generates a colorless grant to utilize the resource wastage, when traffic is light and the total sum of grants of an ONU is less than a minimum size. Using simulation, we validate ECOPS as superior to FCOPS in the mean delay and the service fairness.

In this paper, we propose a new framework for global traffic control in ATM networks which aims to maximize resource utilization and to guarantee the reliable congestion control. To do this, we first propose Global Traffic Control (GTC) mechanism which is based on harmonious cooperation of each traffic control function. GTC measures real bandwidth utilization to compensate inaccuracy of the declared mean cell rate and it also monitors cell losses to manage input traffic load when a network approaches congestion state. We also propose new adaptive connection admission control (CAC) algorithms which calculate cell loss performance of related function blocks in a switch node using only a declared peak cell rate and an estimated mean cell rate. We measure only the mean cell rate of the aggregate cell stream in a link to estimate the mean cell rate of each virtual channel connection. We adopt a peak cell rate spacer at the User Network Interface (UNI) to compensate a cell delay variation (CDV). We will also present an approximation technique to estimate a queue length distribution of a general queue. As this technique requires negligible calculation time, it can meet the stringent requirement on the connection set-up time.

In this paper we propose an effective Peak Rate Spacer (PRS) which can guarantee the negotiated peak cell rate almost perfectly even though contention of cells in the output link of the spacer occurs. We also propose a state-dependent Mean cell Rate Policer-Spacer (MRPS) which can manage the cell loss rate properly by controlling the buffer read rate according to the buffer state. As the MRPS has a cell buffer, it intrinsically has a traffic shaping function. Simulation results clearly show effectiveness of our PRS and MRPS.

A new partitioning configuration that divides a given network into overlapped protection areas is investigated. If two working sub-paths are in the adjacent different working areas, their corresponding protection sub-paths can share a wavelength on the link that belongs to the overlap between two adjacent protection areas. The objective of overlapping is to increase sharing of the protection sub-paths that belong to the adjacent protection areas. The performances of resource utilization and recovery time are improved without any significant degradation of other performances.

In Wireless Sensor Networks (WSNs), sensor nodes consume their limited battery energy to send and receive data packets for data transmission. If some sensor nodes transmit data packets more frequently due to imbalance in the network topology or traffic flows, they experience higher energy consumption. And if the sensor nodes are not recharged, they will be turned off from the lack of battery energy which will degrade network sustainability. In order to resolve this problem, this paper proposes an Energy-aware MAC Protocol (EMP), which adaptively decides on the size of the channel polling cycle consisting of the sleep state (not to communicate with its target node) and the listening state (to awaken to receive data packets), according to the network traffic condition. Moreover, in accordance with the remaining energy state of the sensor node, the minimum size of the channel polling cycle is increased for better energy saving. For performance evaluation and comparison, we develop a Markov chain-based analytical model and an event-driven simulator. Simulation results show that a sensor node with EMP effectively reduces its energy consumption in imbalanced network condition and traffic flows, while latency somewhat increases under insufficient remaining energy. As a consequence, a holistic perspective for enhanced network sustainability can be studied in consideration of network traffic condition as well as the remaining energy states of sensor nodes.

This paper proposes an efficient fair queuing algorithm, called Medium Starting Potential Fair Queuing (MSPFQ), which has O(1) complexity for the virtual time computation while it has delay and fairness properties similar to Starting-Potential Fair Queueing (SPFQ). The key idea of MSPFQ algorithm is that it recalibrates the system virtual time to the medium value of the minimum possible virtual start times of HOL packets in each backlogged session. We show that MSPFQ belongs to the class of Rate-Proportional Server (RPS). In addition, we analytically prove that our algorithm has good delay and fairness properties.

WFQ (Weighted Fair Queueing) is an ideal scheduling algorithm in terms of delay and fairness. However, timestamp computation complexity makes the implementation difficult. In this paper we propose an efficient and simple fair queueing algorithm, called Emulated Weighted Fair Queueing (EWFQ), which has O(1) complexity for the virtual time computation while it almost perfectly emulates the delay and fairness properties of WFQ. The key idea of EWFQ is that it calibrates the system virtual time only at the end of each packet transmission, while it calculates the system virtual time for a newly arrived packet by employing a linear approximation. By doing so, EWFQ has a rate-proportional property. EWFQ can be implemented in a router for supporting the differential and integrated services.

In wavelength division multiplexed networks, shared path protection provides the same level of protection against a single fiber-link failure as dedicated path protection with potentially higher network utilization. The shared path protection is more complex to provision and maintain. In this paper, we introduce a parameter, the degree of sharing, which refers to the number of protection paths that a wavelength can be assigned to on a link. We propose methods for calculating the maximum degree of sharing. We consider on-line routing and wavelength assignment (RWA) of protection paths that are established for incremental traffic using the maximum degree of sharing. Establishment of protection paths using the maximum degree of sharing can simplify the algorithm. We compare the results on the decreased calculation time with accepted connection requests for a given number of wavelengths, assuming that wavelengths are assigned according to the First-Fit policy for working paths and Last-Fit policy for protection paths. The more wavelengths are used, the more calculation time can be reduced. When the load increases, the decreasing rate of calculation time also increases.

We propose a simple and scalable scheduler called Elapsing Time-based Priority (ETP) scheduler for the optical burst switch (OBS) control channel; it eliminates the requirements of global synchronization and core-state information. This scheduler reduces edge-to-edge delays of burst control packets and total latencies of data bursts.

OpenFlow, originally proposed for campus and enterprise network experimentation, has become a promising SDN architecture that is considered as a widely-deployable production network node recently. It is, in a consequence, pointed out that OpenFlow cannot scale and replace today's versatile network devices due to its limited scalability and flexibility. In this paper, we propose OpenQFlow, a novel scalable and flexible variant of OpenFlow. OpenQFlow provides a fine-grained flow tracking while flow classification is decoupled from the tracking by separating the inefficiently coupled flow table to three different tables: flow state table, forwarding rule table, and QoS rule table. We also develop a two-tier flow-based QoS framework, derived from our new packet scheduling algorithm, which provides performance guarantee and fairness on both granularity levels of micro- and aggregate-flow at the same time. We have implemented OpenQFlow on an off-the-shelf microTCA chassis equipped with a commodity multicore processor, for which our architecture is suited, to achieve high-performance with carefully engineered software design and optimization.

Recently, the Guaranteed Frame Rate (GFR) service was proposed as a new service category of ATM to support non-realtime data applications and to provide the minimum rate guarantee. To keep the simplicity of GFR as much as possible and overcome defects of FIFO-based mechanisms, we propose a FIFO-based algorithm extending DFBA one to improve the fairness and provide the minimum rate guarantee for a wider range of Minimum Cell Rate (MCR). The key idea is controlling the number of CLP1 cells which are occupying more buffer space than the fair share even when the queue length is below Low Buffer Occupancy (LBO).