Huhnkuk Lim

An optical packet switch with hybrid buffer structure for contention resolution of asynchronous variable length packets

We propose an optical packet switch (OPS) using a hybrid buffer structure for contention resolution of asynchronous variable length packets. The hybrid buffer consists of a fiber delay line (FDL) buffer as the prime buffer and a shared electronic buffer as the supplementary buffer. For the performance evaluation, a modified void filling scheduling algorithm that can be applied to the OPS was proposed. Simulation results show that the use of the electronic buffer together with the FDL buffer significantly reduce the number of FDL required for contention resolution and considerably lower packet loss.

Virtual-node-based multicast routing and wavelength assignment in sparse-splitting optical networks

This paper investigates several problems associated with optical multicast routing and wavelength assignment in sparse-splitting optical networks for interactive real-time media distribution. Unfortunately, the constrained multicast routing with optimized wavelength assignment leads to NP-complete condition. Thus, in this paper, a virtual-node-based multicast routing algorithm is first proposed to satisfy the requirements of interactive real-time multicasting as well as the constraints from underlying optical networks. For the constructed multicast tree, we then associate an effective wavelength assignment algorithm. The experimental results show that the proposed algorithm combination performs well in terms of (1) the wavelength channel cost, (2) the maximum variation of inter-destination node delays, (3) the signal quality, and (4) the number of wavelength conversions.

Implementation of a front-end and back-end NDN system for climate modeling application

Named Data Networking (NDN), one of the future Internet architecture, is recently emerging as a solution to changing traffic pattern of traditional end-to-end host-centric network systems. To achieve this, NDN has several distinctive features such as name based forwarding and in-network caching. Data-intensive science that handles large-scale experiment and simulation datasets suffers from severe problems in terms of transmitting and processing of a huge amount of datasets. In this paper, to support NDN based data-intensive science application, especially in climate modeling application, we design and implement new NDN components. Our development supports data-centric climate data file searching and publishing, which are a front-end engine in consumer and a back-end engine in producer.

Number of tunable wavelength converters and internal wavelengths needed for cost-effective design of asynchronous optical packet switching system with shared or output fibre delay line buffer

Optical packet switching (OPS) is being considered as one of the switching technologies for a future optical internet. For contention resolution in an optical packet switching (OPS) system, the wavelength dimension is generally used in combination with a fibre delay line (FDL) buffer. In this study, the authors propose to reduce the number of tunable wavelength converters (TWCs) by sharing TWCs for cost-effective design of an asynchronous OPS system with a shared or an output FDL buffer. Asynchronous and variable-length packets are considered in the OPS system design. To investigate the number of TWCs needed for the OPS system, an algorithm is proposed, which searches for an available TWC and an unused internal wavelength, as well as an outgoing channel. This algorithm is applied to an OPS system with a shared or an output FDL buffer. Also, the number of internal wavelengths (i.e. the conversion range of the TWC) needed for an asynchronous OPS system is presented for cost reduction of the OPS system.

Optimization of Tunable Wavelength Converters and Internal Wavelengths in the Optical Packet Switch with Shared FDL Buffer

In an effort to reduce switch cost, we present the optimum numbers of tunable wavelength converters (TWCs) and internal wavelengths required for contention resolution of asynchronous and variable length packets, in the optical packet switch (OPS) with the shared fiber delay line (FDL) buffer. To optimize TWCs and internal wavelengths related to OPS design cost, we proposed a scheduling algorithm for the limited TWCs and internal wavelengths. For three TWC alternatives (not shared, partially shared, and fully shared cases), the optimum numbers of TWCs and internal wavelengths to guarantee minimum packet loss are evaluated to prevent resource waste. Under a given load, TWCs and internal wavelengths could be significantly reduced, guaranteeing the same packet loss as the performance of an OPS with full TWCs and internal wavelengths.

Optimum Numbers of Tunable Wavelength Converters and Internal Wavelengths in the Optical Packet Switch with Shared FDL Buffer

In an effort to reduce switch cost, we, for the first time, present the optimum numbers of tunable wavelength converters (TWCs) and internal wavelengths required for contention resolution of asynchronous and variable length packets, in the optical packet switch (OPS) with the shared fiber delay line (FDL) buffer. To optimize TWCs and internal wavelengths related to an OPS design cost, we proposed a scheduling algorithm for the limited TWCs and internal wavelengths. For three TWC alternatives (not shared, partially shared, and fully shared cases), the optimum numbers of TWCs and internal wavelengths to guarantee minimum packet loss are evaluated to prevent resource waste. Under a given load, TWCs and internal wavelengths could be significantly reduced, guaranteeing the same packet loss as the performance of an OPS with full TWCs and internal wavelengths

EPSB (Electronic Partially Shared Buffering): A Buffering Scheme for Asynchronous and Variable Length Optical Routing for the Edge Optical Packet Switch

We propose a new buffering scheme for wavelength division multiplexing (WDM) packet switching: the Electronic Partially Shared Buffering (EPSB) scheme. This buffering scheme incorporates separate buffers (i.e., electronic buffers) for all the outputs to share in addition to a prime buffer (i.e., the fiber delay line (FDL) buffer) dedicated to all the outputs. By using this EPSB scheme in cooperation with the proposed outgoing data channel scheduling algorithm, a lower packet loss probability can be achieved with fewer FDLs.

Named data networking testbed for scientific data

Named Data Networking (NDN) is one of the future internet architectures, which is a clean-slate approach. NDN provides intelligent data retrieval using the principles of name-based symmetrical forwarding of Interest/Data packets and innetwork caching. The continually increasing demand for rapid dissemination of large-scale scientific data is driving the use of NDN in data-intensive science experiments. In this paper, we establish an intercontinental NDN testbed. In the testbed, an NDN-based application that targets climate science as an example data intensive science application is designed and implemented, which has differentiated features compared to those of previous studies. We verify experimental justification of using NDN for climate science in the intercontinental network, through performance comparisons between classical delivery techniques and NDN-based climate data delivery.

Distributed Hybrid Research Network Operations Framework

Distributed Virtual Network Operations Center (dvNOC) presents virtualized network management framework on hybrid research networks for both network operators and end-users (e.g. researchers) to monitor and manage their own virtual networks. Another purpose of dvNOC is to meet the network demands of advanced applications on hybrid research networks, e.g. very high bandwidth, no datagram loss, almost zero jitter with strict traffic isolation. Based on hierarchical architecture consisting of dNOC (distributed NOC) and vNOC (virtual NOC), users can acquire three functionalities, multi-domain network awareness, efficient NOC-to-NOC cooperation, and user-oriented virtual network management, which are essential elements to achieve automated and virtual network management based on users, over multi-national and inter-domain hybrid research networks.

A Hybrid Overlay Multicast Scheme based on Host Group Model for Subnet-Dense Receivers

Currently multimedia services for customers are rapidly being deployed (e.g. IPTV), and scalable multicasting is required for the needs of the services, e.g. robustness, security, and QoS. While native IP multicast is considered a good solution for the multimedia services, variety of overlay multicast mechanisms have been suggested to remove the barriers that block deployment of IP multicast on Internet. However, most of overlay multicast mechanisms do not consider host group model, which is not a problematic portion, but an advantageous feature of traditional IP multicast in terms of scalability, robustness, and security. In this paper, we propose a hybrid and hierarchical scheme to take advantages of both IP multicast and overlay multicast, based on host group model to gain performance efficiency for many group members on subnet dense mode. Overall network performance enhancement is shown in the performance analysis of our scheme, regarding low latency, small stress, and optimal stretch for multimedia receivers in subnet dense mode.