Jaiseung Kwak

Design and implementation of QoS measurement and network diagnosing framework for IP multicast in advanced collaborative environment

The access grid for collaborative environment exploits IP multicast. Although the IP multicast is quite a promising technology, it faces lots of challenges such as unreliable data transport and unstable network infrastructure. As a first step to achieve reliability and stability in IP multicast, it is essential to monitor and debug multicast networks. In this paper we introduce MMag, a user-oriented multicast monitoring tool for the access grid. The MMag provides both application and network level monitoring facilities to assess delivery statistics and to diagnose multicast problems. The implementation has been tested and will support access grid operators with a simple yet extensive view of multicast performance.

Performance analysis of queue scheduling mechanisms for EF PHB and AF PHB in DiffServ networks

Expedited Forwarding Per-Hop Behavior (EF PHB) and Assured Forwarding Per-Hop Behavior (AF PHB) are the forwarding schemes operating in DiffServ networks. EF PHB is appropriate for flows with low delay, low latency and low jitter, and AF PHB provides guaranteed services with minimum bandwidth and buffer. The two PHB can be implemented by several queue scheduling mechanisms such as weighted round-robin (WRR), priority round-robin (PRR) and priority-weight round-robin (PWRR) which is the queue scheduling mechanism conjoining the WRR and PRR. The EF queue in PWRR is served based on PRR, and WRR mechanism is used in scheduling non-EF queues. In this paper, we evaluate the WRR, PRR and PWRR under the conditions that both EF PHB and AF PHB operate in a DiffServ router. We show PWRR is the best queue scheduling mechanism simultaneously gratifying the delay and jitter criteria of the EF class as well as the target throughput of AF classes.

Two-Tier Call Admission Control to Minimize CBP/CDP in Heterogeneous Wireless Networks

This paper proposes a two-tier call admission control scheme for the efficient use of cellular/WLAN integrated resource. The proposed two-tier call admission control has two separated policies for 3 G cellular network and WLAN. Using the proposed call admission control, the call blocking probability and call dropping probability for voice and data calls are reduced and validated by simulations.

A sophisticated base station centralized simple clustering protocol for sensor networks

In wireless sensor networks, energy efficiency has been a key factor. So far, many energy-efficient routing protocols have been proposed and much attention has been paid to cluster-based routing protocols due to their advantages. However, some cluster-based sensor network routing protocols need location information of the sensor nodes in the network to construct clusters efficiently. Owing to the cost, it is not feasible to know the locations of all sensor nodes in the sensor network. In this paper, we propose a sophisticated base station centralized simple clustering protocol (SBCSP). The proposed protocol utilizes the remaining energy of each sensor node, standard deviation of their energy consumed and the number of cluster heads changed depending on the number of sensor nodes alive in the sensor network. Throughout the performance experiments, we show that SBCSP has better performance than low-energy adaptive clustering hierarchy (LEACH).

Emerging network technologies and network neutrality conformance

The Network Neutrality principle states that, In order to preserve the openness of the Internet, Internet Service Providers (ISP) should be prohibited from blocking or differentiating between content from different application providers, and the end users should have equal access to all legal content on the Internet. The Network Neutrality issue is critical as it can have a considerable impact on the future Internet design principles and associated laws and policies. In this paper, we discuss some of the challenges in monitoring Network Neutrality conformance, focusing on the content provider discrimination. In addition we discuss the emerging network technologies such as Giga-LTE, LTE in Unlicensed spectrum (LTE-U) or Licensed Assisted Access (LAA), LTE Broadcast, LTE Wi-Fi Aggregation (LWA), MulteFire, etc., and discuss how they may affect Network Neutrality.

Analysis on Effect of TCP Retransmission to Energy Consumption on End-to-End Data Transfer

A packet loss caused TCP segment drop and retransmission. This makes the energy useless, which is consumed to deliver the whole packets of the dropped segment over many hops. In this paper, end-to-end TCP retramission will be analyzed for the effect to energy consumed for delivering data. Especially, this paper will compare and analyze the legacy TCP method and Store-and-Forward method, and the method of computing the energy efficiency to transmission loss. This paper expects that the proposed method can contribute to new energy saving decision or algorithm on diverse data transmission situation.

Performance Evaluation of Gigabit Ethernet Interfaces

In high performance computational environments, communication stands out as the major limiting factor to performance. However, high speed network infrastructures are constructed and high speed data transfer protocols, such as BIC TCP and UDT, are capable of transferring the data at the speed of 6~7 Gbps. Despite these circumstances, normal PC users, still have difficulties transferring bulk data in 1 Gbps network. In this paper we try to find out performance limiting factor in end systems. First of all, we investigate the performance effect according to types of NIC and we characterize the current capabilities of PCI, PCI-X and PCI-E Gigabit Ethernet Interfaces and identify requisite components for optimal performance.

MEET: multicast debugging toolkit with end-to-end packet trace

The Access Grid (AG) for collaborative environment exploits IP multicast, which is quite a promising technology for sharing network bandwidth. IP multicast however, faces lots of challenges such as unreliable data transport and immature network infrastructure. As a step to improve reliability and stability in IP multicast, it is essential to properly monitor and debug multicast networks. In this paper we introduce MEET (Multicast debugging toolkit with End-to-End packet Trace), an user-oriented multicast debugging toolkit for AG. MEET provides proactive ways of debugging multicast reachablility and measuring end-to-end delivery statistics. We are sure that MEET supports multicast users with a simple yet extensive view of end-to-end multicast reachability and delivery statistics.