Ho Yong Ryu

QoS support for advanced multimedia systems

An advanced multimedia system is being standardized in ITU-T SG16. One of the primary features of the multimedia system is the inclusion of QoS functions from the outset. This paper presents a possible QoS framework for the multimedia system, which permits multimedia applications to request and acquire QoS for its applications in multi-provider networks. The presented framework is independent of the QoS architecture, mechanisms and tools supported in the network domain. The intention is that irrespective of the QoS mechanisms deployed in the network, multimedia applications can negotiate and acquire QoS from the network in an end-to-end manner.

Design and implementation of Martini based Layer 2 VPN

A VPN is a network composed of hosts and system in different locations. In the past, the most common way to connect these sites was to use an ATM or frame relay leased line, supplied by a service provider. These were traditionally straightforward to provide, as service provider networks were often implemented using a variety of protocols including ATM and frame relay. Recently, service providers have been looking at alternative technologies for creating VPN solutions. For supporting Layer 2 VPN service, MPLS protocol such as LDP, RSVP-TE should be implemented for supporting LSP and LDP proposed by Martini or BGP extended by Kompella. Also, MPLS protocol should be implemented for negotiating the specific virtual circuit. In this paper, we implement the Layer 2 VPN that is controlled by Martini protocol and static. And we evaluate the Layer 2 data traffic including both LSP protection and QoS features

A Residual Power Balancing Routing by Traffic-Splitting Transmission in Mobile Ad-Hoc Networks

In Mobile Ad-hoc Network (MANET), in order to reduce the battery consumption, much research have been studied so far especially on routing algorithm. This paper proposes Residual Power Balancing Routing (RPBR) scheme which uses multiple traffic paths to make every nodes battery in the topology being consumed fairly, so that it could use the path longer and send more data without experiencing path failures. Like Time Delay On-demand Routing (TDOR) scheme does, the proposed scheme, RPBR, use Packet Holding Time at each mobile ad hoc node when configuring the paths. Unlike TDOR, the proposed scheme mainly aimed at multiple paths data transmission and multiple traffic flow environment. To evaluate the performance, we compared the RPBR scheme with TDOR routing and conventional AODV routing in terms of the fairness of residual power dispersion, path connection holding time, and path re-configuration overhead.

A Pseudo State-Based Distributed DoS Detection Mechanism Using Dynamic Hashing ∗

As distributed denial-of-service (DDoS) attacks have caused serious economic and social problems, there have been numerous researches to defend against them. The current DDoS defense system relies on a dedicated security device, which is located in front of the server it is required to protect. To detect DDoS attacks, this security device compares incoming traffic to known attack patterns. Since such a defense mechanism cannot prevent an influx of attack traffic into the network, and every packet must be compared against the known attack patterns, the mechanism often degrades the service. In this paper, we propose a pseudo state-based DDoS detection mechanism using dynamic hashing scheme, which runs on network devices to defend against DDoS attacks without sacrificing performance in terms of data forwarding. The proposed mechanism is suitable for both low- and high-rate attacks. In addition, we verified the performance of the proposed mechanism by evaluating its performance using a DDoS attack similar to the one that occurred in Korea and the USA on July 7th, 2009.