Eunsook Kim

Enhanced Communications Transport Protocol for Multicast Transport

This paper proposes a new multicast transport protocol, called the Enhanced Communications Transport Protocol (ECTP). The proposed protocol is currently being standardized in the ITU-T SG7 and ISO/IEC JTC 1/SC 6. The ECTP is designed to support tightly controlled multicast connections. The sender is at the heart of one-to-many multicast group communications. The sender is responsible for overall connection management such as connection creation, termination, pause, resumption, and the join and leave operations. For tree-based reliability control, ECTP configures a hierarchical tree during connection creation. Error control is performed within each local group defined by a control tree. Each parent retransmits lost data in response to retransmission requests from its children. ECTP has been implemented and tested on Linux machine, along with Application Programming Interfaces based on Berkeley sockets.

QoS support based on IntServ/DiffServ for SIP-based applications

This paper presents a design and implementation of an extended SIP to support QoS on IntServ/DiffServ networks. This paper is focused on describing the extended architecture of SIP UA for supporting QoS demands and the designed network interface module that bridges extended SIP UA and QoS supporting network protocols.

A router-assisted session tree configuration mechanism for reliable multicast

A session tree based mechanism provides an efficient method to avoid well-known feedback implosion. However, it is not easy to configure an efficient session tree for IP multicast because it does not provide any explicit membership and routing topology information to the upper layer protocol. Incongruity between a session tree built on the transport layer and the corresponding routing tree on the network layer would incur large cost to handle control messages. This problem can be solved if a router that knows the information of routing topology can support the configuration of a session tree. Thus this letter proposed a router-assistant mechanism which minimizes the change of router functions and allows the routers to assist in providing a reliable multicast transport service.

Standardization activities on ICTs & climate change

Information and Communication Technology (ICT) sector was observed to emit 2 to 2.5 % of GHG among the total GHG emission. However, it is predicted that ICT sector will be one of the major GHG sources as it could be reach to 10 to 15 % of the total emission by the increased use of ICTs on our life and many sectors. Major International standard bodies have started to study on reducing CO2 emission from ICTs. The study includes methods to measure electricity consumed by ICTs, to reduce the rate of electricity usage and to use of non-fossil fuel sources, which will be key methods to control the carbon footprint of the ICT sector. This paper attempts to introduce the on-going standardization activities on ICTs and climate change.

A New Delivery Scheme for 1-to-N Multicast Applications

We propose a new delivery scheme for 1-to-N multicast applications such as webcasting service used for the web-based broadcasting of contents streams in Internet. The proposed scheme is based on the unicast transport from a remote sender to a subnet host and the subsequent multicast transmissions to the other receiving hosts within the subnet. The main design goal of this scheme is to improve transmission efficiency over the existing unicast transports, without help of multicast-capable networks. The proposed scheme has been tested and compared with the unicast-only transports in terms of the amount of traffic generated in the subnetworks. From experimental results, we see that the proposed scheme provides a nearly same performance as IP multicasting does in the subnetwork environments. Recognizing that IP multicast seems to be a little more delayed, it is expected that the proposed scheme can be used as an alternative short-term solution for one-to-many multicast services over the unicast networks.

A Router Assisting Control Tree Configuration Mechanism for Reliable Multicast

For reliable multicast service, the mechanism based on hierarchical control tree can be a promising solution to avoid well-known feedback implosion. However, configuration of an efficient control tree is very difficult for IP Multicast because it does not provide explicit membership and routing topology information to upper layer protocol. If the transport layer tree and the network layer tree are very different, it may take large cost to handle control messages. Especially, when a node at a downstream link of the network routing tree becomes a parent node of an upstream link at the control tree of transport layer, the discrepancy between routing tree and control tree causes to waste network resources by redundant messages. This problem can be solved if router that knows the information on routing topology can support configuration of a control tree and reliable delivery. However, the change of router function embraces deployment problem. Thus, this paper proposed a very simple method of router assist to minimize change of router functions. With this method, routers are only required to recognize message types of control messages in order to forward the messages to correct direction: upstream or downstream.

A session tree creation mechanism with router assist for reliable multicast

For reliable multicast service, the hierarchical control tree based mechanism can be a promising solution to avoid the well-known feedback implosion. To configure a logical tree is difficult because IP multicast does not provide explicit membership and routing topology information to upper layer protocols. Because of this problem, the transport layer tree may not be congruent with the underlying routing tree, and in this case, reliable multicast services may incur a large cost. This problem can be solved if the router that knows that the routing topology can support configuration of a control tree and reliable delivery. Thus, this paper proposes a router-assist mechanism which uses very simple methods to allow the routers to assist in providing a reliable multicast transport service.

A design and analysis of top-down based ACK-trees

For reliable multicast service, to use a tree hierarchy can be a promising solution to avoid the well-known ACK-implosion. However, to build an efficient ACK-tree is very difficult for IP multicast because it does not provide explicit membership and routing topology information to the upper layer protocol. Due to the difficulties, not much study has been done on the control tree configuration yet, while it immensely affects the behavior and performance on a protocol using the mechanism. Previous approaches can be classified into top-down and bottom-up, and promising previous works have typically been focused on the bottom-up construction mechanism, because the top-down approach has some drawbacks like long tree creation time. However, the ERS-based mechanism, one of the representative bottom-up mechanisms, is known to cause heavy message overhead. Thus, we propose a novel method which takes the benefits of the top-down approach while relieving its most significant drawback, long tree creation time, adopting the concurrent tree creation concept from the bottom-up approach. We show the proposed mechanism reduces message overhead as well as builds a low level of tree. In addition, we achieve medium performance on tree creation time.