Browsing by Author "Tsai, Chia-Tai"

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Design and Implementation of High Availability OSPF Router
(2010-11-01)
Tsai, Chia-Tai
;
Jan, Rong-Hong
;
Wang, Kuochen
;
資訊工程學系
;
Department of Computer Science
In this paper, we propose a High Availability Open Shortest Path First (HA-OSPF) router which consists of two OSPF router modules, active and standby, to support a high availability network. First, we used the continuous-time Markov chain (CTMC) to analyze the steady-state availability of an HA-OSPF router with one active router and N standby routers (1 + N redundancy model). Then, with the failure detection and recovery rate considered, from analytic results, we show that the HA-OSPF router with 1 + 1 redundancy model, one active and one standby, is the preferred model for enhancing router availability. We also show that the carrier-grade HA-OSPF router availability (i.e., five-nine availability) can be achieved under an appropriate combination of the router module failure rate (lambda), repair rate (mu), and the failure detection and recovery rate (delta). Since there is a lack of research on the integration of the redundancy model, link state information backup, and failure detection and recovery, we propose a high availability management middleware (HAM middleware) framework to integrate these three elements. The HAM middleware consists of Availability Management Framework (AMF) service, Checkpoint service, and Failure Manager. It supports health check, state information exchange, and failure detection and recovery. Each HA-OSPF router was designed to have a Linux operating system, HAM middleware, and OSPF process. We have implemented the HA-OSPF router on a PC-based system. Experimental results show that the failure detection and recovery times of the proposed PC-based HA-OSPF router were reduced by 98.76% and 91.45% compared to those of an industry standard approach, VRRP (Virtual Router Redundancy Prctocol), for a software failure and a hardware failure, respectively. In addition, we have also implemented the HA-OSPF router on an ATCA (Advanced Telecom Computing Architecture) platform, which can provide an industrial standardized modular architecture for an efficient, flexible, and reliable router design. Based on our ATCA-based platform with 1/delta = 217 ms for a software failure and 1/delta = 1066 ms for a hardware failure, along with the router module data, 1/lambda = 7 years and 1/mu = 4 hours, obtained from Cisco, the availabilities of the proposed ATCA-based HA-OSPF router are 99.99999905% for a software failure and 99.99999867% for a hardware failure. Therefore, the experimental results have shown that both our proposed ATC A-based and PC-based HA-OSPF routers with 1 + 1 redundancy model can easily meet the requirement of carrier-grade availabilities with five-nine.
Design and Implementation of High Availability OSPF Router
(2010-11-01)
Tsai, Chia-Tai
;
Jan, Rong-Hong
;
Wang, Kuochen
;
資訊工程學系
;
Department of Computer Science
In this paper, we propose a High Availability Open Shortest Path First (HA-OSPF) router which consists of two OSPF router modules, active and standby, to support a high availability network. First, we used the continuous-time Markov chain (CTMC) to analyze the steady-state availability of an HA-OSPF router with one active router and N standby routers (1 + N redundancy model). Then, with the failure detection and recovery rate considered, from analytic results, we show that the HA-OSPF router with 1 + 1 redundancy model, one active and one standby, is the preferred model for enhancing router availability. We also show that the carrier-grade HA-OSPF router availability (i.e., five-nine availability) can be achieved under an appropriate combination of the router module failure rate (lambda), repair rate (mu), and the failure detection and recovery rate (delta). Since there is a lack of research on the integration of the redundancy model, link state information backup, and failure detection and recovery, we propose a high availability management middleware (HAM middleware) framework to integrate these three elements. The HAM middleware consists of Availability Management Framework (AMF) service, Checkpoint service, and Failure Manager. It supports health check, state information exchange, and failure detection and recovery. Each HA-OSPF router was designed to have a Linux operating system, HAM middleware, and OSPF process. We have implemented the HA-OSPF router on a PC-based system. Experimental results show that the failure detection and recovery times of the proposed PC-based HA-OSPF router were reduced by 98.76% and 91.45% compared to those of an industry standard approach, VRRP (Virtual Router Redundancy Prctocol), for a software failure and a hardware failure, respectively. In addition, we have also implemented the HA-OSPF router on an ATCA (Advanced Telecom Computing Architecture) platform, which can provide an industrial standardized modular architecture for an efficient, flexible, and reliable router design. Based on our ATCA-based platform with 1/delta = 217 ms for a software failure and 1/delta = 1066 ms for a hardware failure, along with the router module data, 1/lambda = 7 years and 1/mu = 4 hours, obtained from Cisco, the availabilities of the proposed ATCA-based HA-OSPF router are 99.99999905% for a software failure and 99.99999867% for a hardware failure. Therefore, the experimental results have shown that both our proposed ATC A-based and PC-based HA-OSPF routers with 1 + 1 redundancy model can easily meet the requirement of carrier-grade availabilities with five-nine.
Implementation of Highly Available OSPF router on ATCA
(2007)
Tsai, Chia-Tai
;
Jan, Rong-Hong
;
Chen, Chien
;
Huang, Chia-Yuan
;
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.
Optimal modulation and coding scheme allocation of scalable video multicast over IEEE 802.16e networks
(2011)
Tsai, Chia-Tai
;
Jan, Rong-Hong
;
Chen, Chien
;
資訊工程學系
;
Department of Computer Science
With the rapid development of wireless communication technology and the rapid increase in demand for network bandwidth, IEEE 802.16e is an emerging network technique that has been deployed in many metropolises. In addition to the features of high data rate and large coverage, it also enables scalable video multicasting, which is a potentially promising application, over an IEEE 802.16e network. How to optimally assign the modulation and coding scheme (MCS) of the scalable video stream for the mobile subscriber stations to improve spectral efficiency and maximize utility is a crucial task. We formulate this MCS assignment problem as an optimization problem, called the total utility maximization problem (TUMP). This article transforms the TUMP into a precedence constraint knapsack problem, which is a NP-complete problem. Then, a branch and bound method, which is based on two dominance rules and a lower bound, is presented to solve the TUMP. The simulation results show that the proposed branch and bound method can find the optimal solution efficiently.
Optimal redundancy allocation for high availability routers
(2010-12-01)
Tsai, Chia-Tai
;
Jan, Rong-Hong
;
Wang, Kuochen
;
資訊工程學系
;
Department of Computer Science
How to optimally allocate redundant routers for high availability (HA) networks is a crucial task. In this paper, a 5-tuple availability function A (N, M, lambda, mu, delta) is proposed to determine the minimum required number of standby routers to meet the desired availability (rho) of an HA router, where N and M are the numbers of active routers and standby routers, respectively, and lambda, mu, and delta are a single router's failure rate, repair rate, and failure detection and recovery rate, respectively. We have derived the availability function, and analytical results show that the failure detection and recovery rate (delta) is a key parameter for reducing the minimum required number of standby routers of an HA router. Thus, we also propose a High Availability Management (HAM) middleware, which was designed based on an open architecture specification, called OpenAIS, to achieve the goal of reducing takeover delay (1/delta) by stateful backup. We have implemented an HA Open Shortest Path First (HA-OSPF) router, which consists of two active routers and one standby router, to illustrate the proposed HA router. Experimental results show that the takeover delays of the proposed HA-OSPF router were reduced by 6, 37.3, and 98.6% compared with those of the industry standard approaches, the Cisco-ASR 1000 series router, the Juniper MX series router, and the Virtual Router Redundancy Protocol (VRRP) router, respectively. In addition, in contract to the industry routers, the proposed HA router, which was designed based on an open architecture specification, is more cost-effective, and its redundancy model can be more flexibly adjusted. Copyright (C) 2010 John Wiley & Sons, Ltd.