June-Koo Kevin Rhee

Ethernet ring protection for carrier ethernet networks

Ethernet technologies are rapidly gaining importance as a prevailing solution for carrier networks. Ethernet ring protection switching, defined in ITU-T Recommendation G.8032, provides a means of achieving carrier network requirements for ring network topologies. This article outlines the novel concepts in this Ethernet ring protection switching mechanism and discusses the fundamental operating principles by which the automatic protection switching (APS) protocol works. In addition, several feature enhancements in protection behavior and solutions being considered for the next phase of standardization are discussed.

Distributed potential field based routing and autonomous load balancing for wireless mesh networks

Congested hot spots and node failures severely degrade the performance of wireless mesh networks. However, conventional routing schemes are inefficient in mitigation of the problems. Considering analogy to physics, we propose a novel distributed potential-field-based routing scheme for anycast wireless mesh networks, which is robust to sudden traffic and network perturbations, effectively balancing load among multiple gateways and mesh nodes with little control overhead. Simulation results exhibit autonomous load balancing and failure-tolerant performance in wireless mesh networking.

Efficient Ethernet Ring Mesh Network Design

Ethernet ring protection (ERP) is an emerging solution for carrier-grade optical Ethernet networking developed as an ITU-T recommendation. The most recent development of the ERP technique provides multi-ring protection in a mesh packet transport network. The ERP configuration and capacity planning in a ring mesh topology can be optimized in the selection of the interconnected ring hierarchy and logical loop prevention block positions. This paper reports the first investigation to understand the designing principles of protected Ethernet ring mesh networks and proposes an optimized design scheme for cost-effective and reliable ERP networking.

IP-Over-WDM Cross-Layer Design for Green Optical Networking With Energy Proportionality Consideration

Energy consumption in a network is becoming the physical limit against the everlasting increase of network traffic in the near future. Current network equipment consumes energy inefficiently due to poor energy-load proportionality of network equipment which causes a vast amount of energy consumption even in an idle state. We investigate and model the energy consumption of packet optical transport networks. Employing integer linear programming, we model and optimize the energy consumption of IP/WDM (IP/WDM) networks with traffic-grooming cross layer designs. Our study shows that energy savings in IP/WDM networks with traffic grooming is not effective unless IP layer equipment is energy proportional. In addition, different network planning schemes are required with respect to energy proportionality of network equipment.

Power and cost reduction by hybrid optical packet switching with shared memory buffering

The power consumption of a network becomes a critical performance metric for a petabit-per-second scale Internet, in addition to the system cost. We investigate the power and cost efficiency of all-optical and electrical technologies to understand the design principle for petabit-scale hybrid optical switch nodes for optical packet and burst switching. In order to achieve an efficient hybrid design, we point out the interesting observation that the use of long packets switched by passive-medium photonic switches can substantially reduce power consumption and system cost. For contention resolution, shared electronic memory buffers are more effective and power efficient than fiber delay line buffers. An empirical optimization exhibits that a traditional all-optical solution is not the best choice for power and cost efficiency. Using passive-medium photonic switches with electronic memory buffers, we can introduce a substantial savings in power and cost, approximately half of those of commercially available optical cross-connect systems, with a packet loss rate as low as 10-6.

Multipath Video Real-Time Streaming by Field-Based Anycast Routing

Wireless mesh networking (WMN) for video surveillance provides a strong potential for rapid deployment in a large community, for which reliability and survivability for real-time streaming are the key performance measure. However, current routing protocols do not provide a robust solution to meet video transmission requirements such as providing load balancing for the high data rate and delay requirements. We propose an application of field-based anycast routing (FAR) protocol, which utilizes rapid routing dynamics inspired by an electrostatic potential field model governed by Poissons equation. This routing metric takes into account geometric proximity and congestion degree in order to increase delivery ratio and decrease end-to-end delay, which determine the quality of the delivered video. In addition, FAR protects node failure with an on-the-fly rerouting process that guarantees the continuity of video streaming. Simulation results show 100% delivery ratio in congestion situations and it shows tolerance to different delay requirements compared with AODV and FDMR protocols in terms of delivering real-time and non real-time video surveillance which verifies FAR as a strong candidate for video transmission over WMN.

Traffic grooming for IP-Over-WDM networks: Energy and delay perspectives

As energy consumption has become a major concern of networks, traffic grooming studies on Internet protocol over wavelength division multiplexing (IP-over-WDM) networks have been revisited for energy-efficient optical network applications. Traffic grooming techniques can save on the number of installed lightpaths and corresponding IP router line cards at the cost of traffic processing overhead. Energy awareness in networking device development has initiated improvement of the energy-traffic proportionality of networking devices. Accordingly, networks will consist of networking devices with a wide range of energy-traffic proportionalities. Therefore, previously known traffic grooming techniques may not achieve energy-efficient networking in high energy-traffic proportional networks. Moreover, the traffic grooming technique tends to prefer longer paths, which are responsible for longer transmission delays. These two concerns trigger investigation of new aspects of heuristic traffic grooming algorithms for green and low delay optical networks consisting of network devices with diverse energy-traffic proportionalities. This paper demonstrates that a heuristic traffic grooming algorithm enhanced by comparison with direct bypass routing improves both energy and delay performances in a high energy-traffic proportionality regime. A hottest-first sorting policy in flow provisioning can further improve delay performance even in a low energy-traffic proportionality regime.

System tolerance of all-optical sampling OFDM using AWG discrete Fourier transform

The fundamental-mode arrayed waveguide grating (AWG) for all-optical discrete Fourier transformer (DFT) shows significant feasibility in the system tolerance of all-optical sampling orthogonal frequency division multiplexing (AOS-OFDM) systems. We discuss the system tolerance of AWG-based DFT designs for 100/160Gbps OFDM transmission system in comparison with coupler-based DFT designs.

MDP based dynamic base station management for power conservation in self-organizing networks

This paper proposes a Markov decision process (MDP) based base station management scheme that dynamically and collectively manages activation of a group of base stations depending on the time-varying traffic demand for power conservation in self-organization networks. Our MDP model is unique in a sense that it accurately captures the dynamics of handover traffic among neighboring cells, and it formulates infeasible actions as constraints in a constrained optimization problem. Simulation results confirm that the proposed scheme can significantly reduce power consumption: 55% of daily power savings, upto 73% of power savings during low traffic periods, and the minimum 23% of power savings even during high traffic periods. Our MDP algorithms find desired optimal policies to deactivate unnecessary base stations without sacrificing network performances.

Reliable Network Design for Ethernet Ring Mesh Networks

A Novel Design Optimization For Reliable Networking Is Investigated In Ethernet Ring Mesh Networks With The Itu-T G.8032 Ethernet Ring Protection Recommendation. Designing An Ethernet Ring Mesh Consisting Of Multiple Rings To Achieve The Maximum Network Availability Is An Np-Complete Problem. We Show That A Graph With Vertex Connectivity Equal To Or Greater Than Two Is A Sufficient Condition For Designing An Ethernet Ring Mesh. A Novel Design Rule With An Efficient Heuristic Algorithm Is Proposed To Find A Design Close To An Optimal Ethernet Ring Mesh In Terms Of Maximum Network Availability. Compared With An Optimal Network Design Algorithm With An Exponential Enumeration Search Cost, The Heuristic Algorithm Achieves Network Availability Nearly As High As That Of An Optimal Design At A Polynomial Cost.