Multicast Availability Research Articles

네트워크 기반 원격 협업 지원을 위한 End-to-End IP 멀티캐스트 모니터링 프레임워크 연구

IP 멀티캐스트는 네트워크 자원을 효율적으로 사용할 수 있는 장점에도 불구하고, 관리도메인 간 정책적 이견 및 멀티캐스트 가용성과 도달성 등 기술적 문제로 인해 활용 확장에 한계를 가지고 있다. 멀티캐스트 오류 등 기술적 문제에 대한 탐지 및 차단은 IP 멀티캐스트의 안정화를 위해 우선적으로 해결되어야 할 과제이다. 본 논문은 네트워크와 네트워킹 환경에 대한 오류의 탐지 및 원인 추정이 가능하며, 효율적 활용 유지 확장을 위해 경편성(portability)과 관리성(manageability)을 갖춘 멀티캐스트 모니터링 프레임워크를 제안한다. 제안된 프레임워크는 IP 멀티캐스트의 가용성, 도달성 및 대화성의 탐지가 가능하며 백그라운드(background) 시험 및 요구형(on-demand) 오류 검증을 통해 네트워킹 환경의 성능 장애 요소들을 추정할 수 있다. 또한, 네트워크 자원을 효율적으로 활용함으로써 프레임워크의 확장성(scalability)을 제공한다. 네트워크 테스트베드에서 행해진 실험을 통해 제안된 프레임워크 확장성과 효용성을 입증한다. Despite its graceful bandwidth saving nature, IP multicast has not been successful in widely spreading and using. Challenging includes policy and technological issues such as inter-domain routing, multicast availability and reachability. Properly detecting and isolating the faults would be the first step to stabilize IP multicast. In this paper, we introduce a scalable multicast monitoring framework. To efficiently cope with multicast network and networking problems, it enlarges its monitoring scopes from collecting delivery statistics to verifying end-to-end multicast availability, reachability and interactivity. We carry out various networking experiments to verify the scalability and feasibility of the proposed framework.

Practical utilities for monitoring multicast service availability

Monitoring has become one of the key issues for the successful deployment of IP multicast in the Internet. During the last decade, several tools and systems have been developed to monitor several different characteristics of IP multicast. In this paper, we focus on one specific monitoring task: monitoring end-to-end multicast service availability in the inter-domain. This task is important to maintain service robustness between sources and receivers. Without this assurance, the multicast infrastructure may become disconnected and essentially unusable. In this paper, we first study existing multicast diagnostic tools (e.g. mping and mtrace) and present their shortcomings in verifying end-to-end multicast availability. Then, we propose new multicast diagnostic utilities ( mcping and mcroute) that can be used to perform various monitoring and measurement functions including verification of end-to-end service availability. We present a sample case study demonstrating the utility of these primitives in detecting and classifying multicast reachability problems in the inter-domain. The proposed utilities introduce only a few modifications to the service architecture and, in exchange, provide the multicast community with effective means to monitor and measure multicast service characteristics.

A low overhead encapsulation method for MF-TDMA

Modern radio systems have to meet demanding criteria, like availability of multicast, broadcast and point-to-point transmission, support of Quality of Service (QoS) and fairness, but also low overhead and low error multiplication. These criteria should all be combined for a successful technology. In this paper we explain the benefits of Low Overhead Encapsulation (LOE) and how it can be properly tailored for a Multi-Frequency-Time Division Multiple Access (MF-TDMA) access scheme.