Browsing by Author "Huang, Chia-Yuan"

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A fast failure detection and failover scheme for SIP high availability networks
(2007)
Wu, Wei-Ming
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Wang, Kuochen
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Jan, Rong-Hong
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Huang, Chia-Yuan
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資訊工程學系
The SIP proxy server, which is an important building block of a SIP network, can be in a form of a cluster to prevent service unavailability caused by software or hardware failures. The design of a SIP proxy server cluster with a single dispatcher in a SIP network faces the single-point-of-failure problem. The use of dual SIP dispatcher architecture was proposed and VRRP (Virtual Router Redundancy Protocol) was used as an JP failover mechanism. In this paper, we have designed and implemented a dependable SIP network that includes n + k SIP dispatchers (n active dispatchers + k backup dispatchers) to control and monitor a cluster of m SIP proxy servers for VoIP and video conferencing applications. A fast failure detection and failover (FFF) scheme has also been proposed. FFF uses OpenAIS as a high availability middleware to perform health check and failover of dispatchers and proxy servers. Experimental results have shown that the FFF scheme reduces the dispatcher failover time by 80% compared to the VRRP mechanism and also shorten the proxy failover time by 85% compared to the mechanism provided by OpenSER itself
Efficient Failover and Load Balancing for Dependable SIP Proxy Servers
(2008)
Cheng, Yun-Jung
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Wang, Kuochen
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Jan, Rong-Hong
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Chen, Chien
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Huang, Chia-Yuan
In this paper, we designed and implemented a dependable SIP-based clustered architecture for VoIP and multimedia applications, and also proposed an efficient OpenAIS-based SIP Load Balancing strategy (OSLB) that can balance proxy servers' load and achieve fast failover by reducing the number of failed calls when one of the dispatchers or one of the SIP proxy servers crashes. Experimental results show that our OSLB is comparable to an existing work, SIP load balancer, in terms of load balance metric (1.05 vs. 1.04). However, our OSLB reduces the number of failed calls by 86% when a proxy server failed compared to the SIP load balancer. This work, which is part of an EPON project, has been realized in an industry standard ATCA-based platform to provide high availability carrier-grade services, and is currently under a field trial In an ISP.
Experience in developing a high availability and continuous TCP using OpenAIS and TCPCP
(2007)
Chen, Ying-Yu
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Chen, Chien
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Huang, Chia-Yuan
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資訊工程學系
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Department of Computer Science
It has become one of the basic requirements for the service providers to deliver highly available services to meet the customers\' critical needs. However, a highly available service does not guarantee that the service is delivered continuously from the user\'s point of view. In this paper, we share the experience of developing high-availability and continuous TCP using open source OpenAIS and TCPCP/TCPCP2. We describe the main system design for building such systems. We specifically discuss two of the problems that need to be overcome under this kind of design model. For each problem and its corresponding resolution, we show a simulation using ns2 simulator, which provides a deeper insight into the problems for further studies. We also develop a simple application which uses OpenAIS and TCPCP2 to achieve its high availability and service continuity. The results indicate that a high availability and service continuity service can be obtained with minor degradation in performance.
Implementation of Highly Available OSPF router on ATCA
(2007)
Tsai, Chia-Tai
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Jan, Rong-Hong
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Chen, Chien
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Huang, Chia-Yuan
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資訊工程學系
This paper proposes a Highly-Available Open Shortest Path First (HA-OSPF) router which consists of two OSPF router modules-active and standby-to support a high-availability network. Each router module runs a Linux operating system, high-availability management middleware (HAM middleware), and OSPF daemon. The HAM middleware consists of an Availability Management Framework (AMF) service, checkpoint service, interface monitor, OSPF fault manager and fault handler; it provides a health check, state information exchange, and takeover mechanism. The experimental results are given to show the system availability), of the HA-OSPF router on a PC-based prototype system. Furthermore, to build a carrier grade commercial product, we realize a HA-OSPF router on an industry standard compliant Advanced Telecom Computing Architecture (ATCA) hardware platform. From actual measurements, we show that our PC-based and ATCA-based HA-OSPF routers take only 166 and 131 ms to switch over to a standby router module when there is a software fault and 360 and 331 ms with a hardware failure respectively.