Hybrid Switching System Research Articles

Adaptive resource management for flow-based IP/ATM hybrid switching systems

This paper addresses a fundamental problem in resource management for flow-based hybrid switching systems. Such systems aim at efficient transport of layer-3 connectionless IP traffic over layer-2 connection-oriented ATM switching fabrics. One idea behind flow-based hybrid switching is to decompose individual IP packet streams into flows and then to classify them into short-lived and long-lived flows. While the short-lived flows are good for forwarding by the embedded software through permanent virtual connections (PVCs), the long-lived flows are more effectively transmitted by hardware through switched virtual connections (SVCs). Clearly the flow identification/classification mechanism will have great impact on the utilization of the system's resources. Our paper focuses on the resources which are directly associated with packet processing power, signaling capacity, and flow cache table size. Our study indicates that the presently available static flow classification methods have a vital shortcoming in balancing the utilization of the system's resources. We propose a novel approach for adaptive flow classification based on the min-max objective for the system resource utilizations to match with the time-varying traffic/resource characteristics based on the monotone properties and sensitivity analysis of the resource utilizations as functions of the control parameters, we first prove that the optimal solution of the static min-max problem is achieved at a unique balance point for the resource utilizations. With the intuition gained from the static results, we then design an adaptive controller formulated as a hierarchical stochastic automata control system with local search. The optimality of the proposed adaptive controller is tested against the static optimal control based on real trace simulations. The simulation studies in highly nonstationary environments show the viability of the proposed flow adaptation for dynamic resource management in hybrid switching system design. The algorithm is simple to implement and only requires the adaptation of two global variables at time intervals of every few seconds based on the present usage of resources.

Performance analysis of a hybrid switching system where voice messages can be queued

In the classical model of a hybrid switching system with movable boundary it is assumed that blocked voice messages are lost and do not affect the further functioning of the system. We describe a more realistic model where blocked voice messages are queued and then are served once a channel becomes free. The main mathematical difficulty in the analysis of such models lies in the fact that the underlying stochastic process has as state space the whole quadrant ℤ+2. We reduce the problem to a set of equations defined over the lattice semi-strip {1,...,N} × ℤ+. This in turn allows us to use available general mathematical theories.

A MODEL FOR VOICE/ DATA INTEGRATION ON S- TDM USING MOVABLE BOUNDARY,HYBRID SWITCHING TECHNIQUE

This paper assesses a model of voice / data integration on statistical time divsion multiplexing technique. A comparison between fixed and movable boundary frame structure is introduced and the selection of a movable boundary than fixed boundary _due to the efficient sharing of voice and data transmission capacity in the frame period with higher channel utilization_ is discussed. Hybrid switching system which combined circuit and packet switching techniques is provided in this model, where the hybrid switching frame period consists of both circuit switched voice traffic and packet switched data traffic The performance of the model is evaluated and the results obtained are analyized , also the blocking probability of voice source and the waiting delay of data packet are measured . The effect of number of slots( N 1,N 2 ) assigned to voice / data sources on the system performance is evaluated. The effect of the offerd voice load on the waiting delay of data packets for the propose' integration model is also provided

Line capacity expansion schemes in photonic switching

Design considerations for capacity expansion are described, and requirements for photonic switch matrices, optical memories, and tunable-wavelength filters are examined. The present status of photonic switching devices and system experiments is discussed, covering space-, wavelength-, and time-division switches. Hybrid switching systems and coherent optical detection are considered as examples of system technology that will facilitate line capacity expansion. >

Photonic wavelength-division and time-division hybrid switching system utilizing coherent optical detection

The application of coherent optical detection to a photonic wavelength-division (WD) and time-division (TD) hybrid switching system for a large-capacity switching is studied. Wavelength switching time is 1.8 ns, and the wavelength is stable after wavelength switching as wide as 3-4 AA. The results suggest the feasibility of switching over 20 channels (TD 4 channels, WD approximately 6 channels) for 100-Mb/s signals. This channel number can be increased to 256 channels (WD 64 channels) in view of the maximum wavelength sweep range (40 AA) of wavelength tunable laser diodes obtained so far.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Applications of matrix-geometric solutions for queueing performance evaluation of a hybrid switching system

AbstractWe consider a hybrid switch which provides integrated packet (asynchronous) and circuit (isochronous) switching. Queue size and delay distribution of the packet switched traffic in the steady state are derived by modelling the packet queue as a queue in a Markovian environment. The arrival process of the packets as well as of the circuit allocation requests are both modelled by a Poisson process. The analysis is performed for several circuit allocation policies, namely repacking, first-fit (involving static or dynamic renumbering) and best-fit. Both exact results and approximations are discussed. Numerical results are presented to demonstrate the effect of increase in packet and circuit loading on the packet delay for each of the policies.

Circuit allocation and overload control in a hybrid switching system

A hybrid switching system which provides integrated packet and circuit switching is considered. The framing structure is based on position multiplexing of the isochronous slots. The switch capacity is dynamically allocated to meet the demand of the synchronous circuits. Due to some wastage inherent in the framing structure, not all of the remaining capacity is available for the packet switched traffic. In order to evaluate the packet capacity, we derive the statistics of the effective bandwidth utilized by the isochronous traffic. Three circuit allocation policies are considered: repacking, first-fit and first-fit involving circuit blocking policy. The analysis takes into consideration the waste created by these policies. Numerical results are presented to compare between the efficiency of these schemes, and to demonstrate, in each case, the effect of circuit loading on the effective capacity utilized by the isochronous traffic which in turn determines the packet capacity.

Bandwidth allocation for bursty isochronous traffic in a hybrid switching system

Consideration is given to a hybrid switch which provides integrated packet and circuit switching. The statistical characteristics of the bandwidth utilized by bursty isochronous traffic are derived. The derivation takes into consideration the waste inherent in the framing structure. Bursty traffic due to circuit allocation requests is modeled by a switched Poisson process. The analysis is performed for two circuit allocation policies, namely, repacking and first-fit with static numbering. Numerical results are presented to demonstrate the effect of traffic burstiness on the capacity utilized by the isochronous traffic.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A study on hybrid switch architecture using hierarchical memory system

AbstractOn the premise that flexibility in communication is a primary objective for future digital networks providing various services, it is highly desirable to integrate circuit switching (CS) and packet switching (PS) functions into a single switching node. This paper proposes a hybrid switching system where PS and CS switching functions are integrated by making use of a hierarchical memory system in which the CS and PS switching buffers and program buffers reside in the same memory area, and the high‐speed memory in the hierarchy can be accessed both by transmission lines and processors. The design concept which adopts a new architecture necessary to meet the above requirement and the evaluation of its call processing capacity using traffic simulation and theoretical analysis are described.

Analysis and Design of Hybrid Switching Networks

This paper presents a methodology for the design of hybrid switching systems. Hybrid switching enables both circuit and packet-switched services to be provided in the same communication network. A model for the analysis of blocking and delay of a hybrid switching link is developed. The capacity assignment problem for hybrid-switched networks is also formulated and solution techniques developed. These models are incorporated into an overall hybrid switching network design methodology, and applied to study alternative system operations.