• ETRI Journal
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• 제33권3호
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• pp.355-365
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• 2011

IPTV broadcast channels and video content distribution are increasingly saturating network paths. New solutions based on inter-domain multicast protocols could contribute to the enhancement of multimedia content distribution over the Internet. The aim of this paper is to propose new capabilities for an existing inter-domain multicast protocol, the Protocol Independent Multicast-Sparse Mode. We describe the modified protocol and analyze its behavior using newly developed tools based on an open-source software simulator. The resulting protocol does not require topology information, which is advantageous for easier deployment. In addition, the adopted solution avoids inherent problems with inter-domain multicast routing, such as multiple paths and path asymmetries.

• Journal of Communications and Networks
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• 제9권4호
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• pp.350-355
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• 2007

Border gateway protocol allows autonomous systems(ASes) to apply diverse routing policies for selecting routes and for propagating reachability information to other ASes. Although a significant number of studies have been focused on the Internet topology, little is known about what routing policies network operators employ to configure their networks. In this paper, we infer and characterize routing policies employed in the Internet. We find that routes learned from customers are preferred over those from peers and providers, and those from peers are typically preferred over those from providers. We present an algorithm for inferring and characterizing export policies. We show that ASes announce their prefixes to a selected subset of providers to perform traffic engineering for incoming traffic. We find that the selective announcement routing policies imply that there are much less available paths in the Internet than shown in the AS connectivity graph, and can make the Internet extremely sensitive to failure events. We hope that our findings will help network operators in designing routing policies.

• Journal of Communications and Networks
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• 제13권6호
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• pp.602-611
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• 2011

The inter-domain routing scalability issue is a major challenge facing the Internet. Recent wide deployments of multihoming and traffic engineering urge for solutions to this issue. So far, tunnel-based proposals and compact routing schemes have been suggested. An implicit assumption in the routing community is that structured address labels are crucial for routing scalability. This paper first systematically examines the properties of identifiers and address labels and their functional differences. It develops a simple Internet routing model and shows that a binary relation T defined on the address label set A determines the cardinality of the compact label set L. Furthermore, it is shown that routing schemes based on flat address labels are not scalable. This implies that routing scalability and routing stability are inherently related and must be considered together when a routing scheme is evaluated. Furthermore, a metric is defined to measure the efficiency of the address label coding. Simulations show that given a 3000-autonomous system (AS) topology, the required length of address labels in compact routing schemes is only 9.12 bits while the required length is 10.64 bits for the Internet protocol (IP) upper bound case. Simulations also show that the ${\alpha}$ values of the compact routing and IP routing schemes are 0.80 and 0.95, respectively, for a 3000-AS topology. This indicates that a compact routing scheme with necessary routing stability is desirable. It is also seen that using provider allocated IP addresses in multihomed stub ASs does not significantly reduce the global routing size of an IP routing system.

• Journal of Communications and Networks
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• 제6권1호
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• pp.60-67
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• 2004

With the fast growth of Internet and a new widespread interest in optical networks, the unparalleled potential of Multi-Protocol Label Switching (MPLS) is leading to further research and development efforts. One of those areas of research is Path Protection Mechanism. It is widely accepted that layer three protection and recovery mechanisms are too slow for today’s reliability requirements. Failure recovery latencies ranging from several seconds to minutes, for layer three routing protocols, have been widely reported. For this reason, a recovery mechanism at the MPLS layer capable of recovering from failed paths in 10’s of milliseconds has been sought. In light of this, several MPLS based protection mechanisms have been proposed, such as end-to-end path protection and local repair mechanism. Those mechanisms are designed for intra-domain recoveries and little or no attention has been given to the case of non-homogenous independent inter-domains. This paper presents a novel solution for the setup and maintenance of independent protection mechanisms within individual domains and merged at the domain boundaries. This innovative solution offers significant advantages including fast recovery across multiple nonhomogeneous domains and high scalability. Detailed setup and operation procedures are described. Finally, simulation results using OPNET are presented showing recovery times of a few milliseconds.

• 융합보안논문지
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• 제17권5호
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• pp.63-69
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• 2017

1990년대 초반에 IETF(Internet Engineering TaskForce)는 IPv4의 주소 고갈 문제에 대한 임시해결책인 CIDR(Classless Inter-Domain Routing), NAT, 사설 IP 주소 등의 도입과 함께 기존 IPv4 주소 체계에서의 많은 단점들을 수정 및 보완할 수 있는 새로운 주소체계 도입에 관한 논의를 시작하였다. 그 결과 새로운 주소 체계와 관련된 다양한 표준안들이 제안되었는데, 이들 중 가장 발전 가능성이 높은 방안으로 SIPP(Simple Internet Protocol Plus)가 채택되어 지금의 IPv6로 발전하였다. 기존의 IPv4에서 실시간 데이터의 처리 능력과 QoS 관련 성능, 보안, 라우팅의 효율성 등의 많은 분야와 관련하여 부족했던 부분들이 수정 및 보완됨과 동시에 새로운 개념들이 도입되었다. 하지만 IPv6 환경에서도 보안을 위협할 만한 다양한 요소들이 존재하며, 이에 따라 안정적인 데이터 통신 환경의 필요성이 꾸준히 제기되어 왔다. 본 논문에서는 일방향으로 데이터를 전송하면 불확실하고 잠재적인 위협 요소로부터 시스템을 보호할 가능성이 높아진다는 점에 착안하여, IPv6 환경에서의 일방향 통신 알고리즘을 개발하였다. 먼저 기반 환경인 IPv6 및 ICMPv6에 대해 조사 및 분석하고 그에 따른 해결방안인 일방향 통신 알고리즘을 제시한다.

• Journal of Communications and Networks
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• 제9권4호
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• pp.490-498
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• 2007

BGP route flap damping(RFD) was anecdotally considered to be a key contributor to the stability of the global Internet inter-domain routing system. However, it was recently shown that RFD can incorrectly suppress for substantially long periods of time relatively stable routes, i.e., routes that only fail occasionally. This phenomenon can be attributed to the complex interaction between BGP path exploration and how the RFD algorithm identifies route flaps. In this paper we identify a distinct characteristic of BGP path exploration following a single network event such as a link or router failure. Based on this characteristic, we distinguish BGP route updates during BGP path exploration from route flaps and propose a novel BGP route flap damping algorithm, RFD+. RFD+ has a number of attractive properties in improving Internet routing stability. In particular, it can correctly suppress persistent route flaps without affecting routes that only fail occasionally. In addition to presenting the new algorithm and analyzing its properties, we also perform simulation studies to illustrate the performance of the algorithm.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2010년도 추계학술발표대회
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• pp.1050-1052
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• 2010

Locator and Identifier Split is considered as the solution to the scalability problem Internet is facing today. The separation approach of Locator and Identifier requires a third party called mapping system. The mapping system enables the inter-domain routing between two different edge networks. The design of this third party has generated many proposals, among them one approach use Border Gateway Protocol (BGP) for effective mapping information updates distribution. In this paper, we take advantage of this approach by considering the scalability in term of mapping information storage. Our goal is to provide scalability in term of mapping information storage as well as effective mapping information updates distribution.