In this paper, we present a component-based network simulation environment that provides a systematic way to simulate, with high fidelity, protocol operations in a variety of target network architectures. We take a four-step approach to developing such a composable network simulation environment with reusable components. First, we lay a component-based software architecture, called the autonomous component architecture (ACA). Second, we propose a new real-time, process-driven simulation technique that fits naturally in ACA and simulates the real system realistically. Third, we devise a packet-based network simulation framework, called extensible internetworking framework (INET), on top of ACA. Fourth, we implement in Java both ACA and INET, and several representative suites of protocol components in a variety of network architectures. The resulting codes, along with a scripting framework, constitute a network simulation environment called J-Sim. By virtue of the many desirable features inherited from ACA, the J-Sim environment meets the flexibility, composability, reusability, extensibility and diagnosability requirements. The price J-Sim pays for the many desirable features is, however, the inter-component communication overhead. In this paper, we show (via experimentation) that this overhead is not significant (in the range of 0.2—0.6 μs), and J-Sim achieves better scalability than two other network simulators in the public domains, ns-2 and Scalable Simulation Framework Network Models (SSFNET), in terms of both the experiment setup time and the simulation completion time.

Wireless sensor networks have gained considerable attention in the past few years. They have found application domains in battlefield communication, homeland security, pollution sensing, and traffic monitoring. As such, there has been an increasing need to define and develop simulation frameworks for carrying out high-fidelity WSN simulation. In this article we present a modeling, simulation, and emulation framework for WSNs in J-Sim — an open source, component-based compositional network simulation environment developed entirely in Java. This framework is built on the autonomous component architecture and extensible internetworking framework of J-Sim, and provides an object-oriented definition of target, sensor, and sink nodes, sensor and wireless communication channels, and physical media such as seismic channels, mobility models, and power models (both energy-producing and energy-consuming components). Application-specific models can be defined by subclassing classes in the simulation framework and customizing their behaviors. We also include in JSim a set of classes and mechanisms to realize network emulation. We demonstrate the use of the proposed WSN simulation framework by implementing several well-known localization, geographic routing, and directed diffusion protocols, and perform performance comparisons (in terms of the execution time incurred and memory used) in simulating WSN scenarios in J-Sim and ns-2. The simulation study indicates the WSN framework in J-Sim is much more scalable than ns-2 (especially in memory usage). We also demonstrate the use of the WSN framework in carrying out real-life full-fledged Future Combat System (FCS) simulation and emulation.

In this paper, we present the design methodology, and the software architecture, of J-Sim, an open-source network simulation/emulation environment that has been developed, in part, under the support of the NSF next generation software program. We first give an overview of the component-based software architecture, called the autonomous component architecture (ACA), that is used as the underlying architecture for J-Sim. Then we describe how we lay a generalized packet-based network simulation framework, called extensible internetworking framework (INET), on top of ACA. Both the ACA and the INET have been implemented in Java. The resulting codes, along with an essential suite of network protocols and components (for the Internet best-effort/integrated services/differentiated services architecture) its extension for wireless and sensor networks, and a scripting framework and GUI interfaces, is called J-Sim. To demonstrate the composability and extensibility of J-Sim, we elaborate on how we model in J-Sim several different network architectures, namely the differentiated services (diffserv) architecture, the multiprotocol label switching (MPLS) architecture, and the wireless sensor network architecture.

Wireless sensor networks (WSNs) have gained considerable attention in the past few years. As such, there has been an increasing need for defining and developing simulation frameworks for carrying out high-fidelity WSN simulation. In this paper, the authors presented a modeling and simulation framework for WSNs in J-Sim - an open-source, component-based compositional network simulation environment that is developed entirely in Java. This framework is built upon the autonomous component architecture (ACA) and the extensible internetworking framework (INET) of J-Sim, and provides an object-oriented definition of (i) target, sensor and sink nodes, (ii) sensor and wireless communication channels, and (iii) physical media such as seismic channels, mobility model and power model (both energy-producing and energy-consuming components). Application-specific models can be defined by sub-classing classes in the simulation framework and customizing their behaviors. The use of the proposed WSN simulation framework was demonstrated by implementing several well-known localization, geographic routing, and directed diffusion protocols. In addition, performance comparisons were performed (in terms of execution time incurred, and the memory used) in simulating several typical WSN scenarios in J-Sim and ns-2. The simulation study indicates that the proposed WSN simulation framework in J-Sim is much more scalable than ns-2 (especially in memory usage).

In this paper, we address the problems of constructing both source-based and core-based many-to-many multicast trees for applications with delay and/or delay jitter constraints. We use the source-destination delay bound and the interdestination delay fitter bound as the QoS requirement and formulate the delay and delay jitter constrained many-to-many multicast tree (D/sup 2/M/sup 3/T) problems. For the source-based, many-to-many multicast paradigm, we extend an existing scheme that builds a one-to-many, QoS-compliant multicast tree and devise a solution scheme that first finds a feasible multicast tree for each source node in the multicast group and then a minimum cover of these multicast trees such that there exists at least one feasible multicast tree in the minimum cover for each source node. For the core-based, many-to-many multicast paradigm, we first derive a necessary and sufficient condition for a core-based multicast tree to be feasible and then devise a solution scheme based on the condition derived. We validate and evaluate both proposed schemes via simulations.

In this paper, we devise a preallocation-based single-hop wavelength division multiple access (WDMA) scheme to support temporal quality of service (QoS) in star-coupled optical networks, We consider a star-coupled broadcast-and-select network architecture in which N stations are connected to a star coupler with W different wavelength channels. Each of the W wavelength channels is slotted and shared by the !V stations by means of time division multiplexing. Depending on the tunability characteristics (tunable or fixed tuned) of the transmitters/receivers, we classify the network architecture as tunable transmitter/fixed tuned receiver (TT-FR), fixed tuned transmitter/tunable receiver (FT-TR), and tunable transmitter/tunable receiver (TT-TR). We first characterize each real-time message stream M/sub i/, with two parameters, the relative message deadline D/sub i/ and the maximum (total) message size C/sub i/ that can arrive within any time interval of length D/sub i/. We then discuss a restricted case in a TT-FR (or FT-TR) system in which the message streams from a source station are assumed to be all destined for the same destination station. Under this assumption, no source destination conflicts may occur. We propose a preallocation-based slot assignment scheme to preallocate slots to a set of isochronous message streams, (M/sub i/=(C/sub i/, D/sub i/)|1/spl les/i/spl les/n) in such a way that, in any time window of size D/sub i/ slots, at least C/sub i/ slots on a wavelength channel are allocated to M/sub i/ for all i. With the solution derived in the restricted case as a basis, we then consider slot assignment in a (general) TT-TR system and propose a binary splitting scheme to assign each message stream sufficient and well-spaced slots to fulfil its temporal requirement, subject to the source/destination conflict constraints. We rigorously prove the invariance properties, and the correctness, of the binary splitting scheme.

This paper describes extension to the core based tree (CBT) protocol to maintain a multicast tree with userspeci ed QoS properties. Speci cally, it describes enhancements in the member join/leave and state update/refresh procedures to facilitate the deployment of additive (e.g., endto-end delay bound), multiplicative (e.g., packet loss ratio along a path) and concave (e.g., minimum bandwidth avail-

In this paper, we propose a packet eligible time calculation mechanism and its associated information update method to provide temporal QoS to multicast services, in terms of delay bound coupled with inter-message delay jitter bound and/or bounded inter-destination delay jitter bound. We assume the availability of a multicast tree on which the delay between a source and any destination falls within the end-to-end delay bound. We then exploit the idea of artificially delaying transmission of data packets until their eligible times, and model each router as a regulator followed by a packet scheduler. A data packet is not eligible to be scheduled until the current time is greater than or equal to its eligible time. For each temporal QoS required, we derive the appropriate packet eligible times. We also devise an information update method to collect/update in a decentralized manner the parameters needed in the calculation of packet eligible times. With all the parameters available, an intermediate router can calculate packet eligible times and the upper bound on the buffers needed in order to fulfill the QoS. Finally, we validate the proposed mechanism in terms of the probability of locating feasible-multicast trees and message overheads, and scalability with event-driven simulations.

We develop and evaluate a set of member join/leave and state update/refresh procedures for QoS provisioning in core-based multicast routing with explicit member join and soft state refresh procedures. Specifically, in our prior work (Hung-Ying Tyan et al., 1999), we devised eligibility tests to verify whether or not a new member can join a multicast tree at adequate QoS while not violating the existing QoS guarantees to other on-tree members. We extend our prior work, identify the tradeoff between the amount of state kept at each on-tree router and the degree of collaboration among on-tree routers to conduct the tests, and develop two member join/leave procedures that range from using the most comprehensive state update procedure (and hence the least degree of collaboration among on-tree routers) to the other extreme. Also, we evaluate the proposed framework, in terms of the probability of locating feasible multicast trees, message overheads, and scalability

We propose a generic rate-based scheduling paradigm that can serve as a vehicle either for implementing existing well-known rate-based message scheduling algorithms, or for designing new rate-based message scheduling algorithms. The proposed scheduling paradigm is general enough to encompass a wide spectrum of rate-based scheduling algorithms and is flexible enough to allow realization of several desirable features, e.g., rate enforcement, capability of handling overbooking, and capability of providing rate parameters for traffic monitoring. Its modular design also facilitates realization of multiple scheduling algorithms in an uniform framework. Different levels of QoS can be provided to applications by invoking appropriate message schedulers implemented in the same framework. We demonstrate the use of the proposed scheduling paradigm by implementing the following two well-known families of message scheduling algorithms: (1) Virtual-Clock and its variations Self-Clocked Pair Queuing and Leap Forward Virtual Clock, and (2) Generalized Processor Sharing (or Weighted Fair Queuing) and its realistic implementations Packet-by-Packet Generalized Processor Sharing and Worst-case Fair Weighted Fair Queuing. We also design a simple message scheduling algorithm, called FIFO-r, using the paradigm, and derive analytically both the actual service rate and the end-to-end delay under FIFO-r