Yu Lin

Bio: Yu Lin is an academic researcher from University of Nebraska–Lincoln. The author has contributed to research in topics: Network topology & Backup. The author has an hindex of 2, co-authored 3 publications receiving 8 citations.

Path-based Protection in WDM Networks with Differentiated Quality-of-Protection

Abstract: The design of a survivable network with path-protection involves the provisioning of a primary and a backup path for every connection request. To optimize bandwidth usage under path-based protection, backup paths are allowed to share bandwidth under single failure model. However, path-based protection does not guarantee fast recovery as switches along a shared backup path may need to be reconfigured according to the particular primary path that needs to be recovered. Pre-cross-connected trail (PXT) addresses this problem by ensuring that backup paths are pre-connected. In practice, different requests may have different tolerance for recovery time. However, PXT does not consider differentiated tolerance and thus may block connections that may tolerate longer recovery times. In this paper, we address the problem of provisioning WDM networks with differentiated quality of protection under the path-based protection scheme. We formulate the problem of path protection with Differentiated Quality-of-Protection (DQoP) under single failure model, and develop an on-line algorithm that relaxes the PXT scheme by enabling the provisioning of requests under two classes of protection services. We consider both node failures as well as link failures. Extensive simulation results on several network topologies and under different traffic models confirm a reduction of up to 13% in blocking probability and up to 4% in bandwidth usage compared to the conventional PXT scheme.

A new approach for fast segment-based protection in WDM mesh networks

Abstract: We propose a new approach for developing segment-based schemes for protection against single link/node failure in wavelength division multiplexing (WDM) mesh networks. In the proposed approach, every request is allocated a pair of link disjoint but most coupled primary and backup paths. Two paths are said to be most coupled if they share the maximum number of end nodes of some existing requests. Coupled paths reduce the total number of hops need to be traversed by a failure signal and, hence, potentially reduces the overall recovery time. We show that the problem of finding a pair of disjoint and most coupled paths is NP-complete. Accordingly, we propose an efficient and fast protection algorithm called SPXP—Segment Pre-Cross-Connected Protection, to allocate disjoint and most coupled paths. The proposed SPXP algorithm reduces the recovery time by ensuring that backup resources are pre-configured along each backup segment and, hence, is readily available upon a failure. Simulation results for different incremental traffic models and network topologies show that, for most cases, the proposed SPXP exhibits better performance in terms of blocking probability, resource usage, and recovery time compared with existing protection schemes. Copyright © 2010 John Wiley & Sons, Ltd.

Designing fast and bandwidth efficient protection scheme for WDM optical networks

Abstract: In this paper, we introduce the Pre-cross-connected Segment First — PXSFirst protection scheme; a new path-based protection schemes for WDM optical networks. The goal of the PXSFirst scheme is to achieve fast recovery, while maximizing bandwidth sharing to improve bandwidth utilization. Similar to pre-cross-connected trails (PXTs) protection scheme, PXSFirst ensures that all backup paths are pre-cross-connected, and hence eliminates the switching configuration delay along backup paths. However, unlike the PXT scheme, where backup paths can only share trails, PXSFirst breaks backup paths into smaller segments by existing end nodes, and hence, increases the possibility of bandwidth sharing. Extensive simulation results for different network topologies and under different traffic patterns show that the proposed scheme has better blocking performance and less bandwidth utilization (an average of 11.0% reduction) compared to existing PXT protection schemes.

Supplementing Non-Simple p-Cycles with Preconfigured Lines

Abstract: This paper considers link based protection where backup capacity is preconfigured into various patterns. When the amount of backup capacity available on a link is constrained, the choice of patterns under consideration can determine if a given network is protectable. This paper gives an ILP that can be used in calculating preconfigurations, even when p-Cycles with p-lines or non-simple p-Cycles alone may not be able to. This ILP includes constraints that will cause backup capacity to be distributed in a somewhat even fashion when possible. When considering networks with dynamic traffic, this may offer the advantage of lower blocking probability over schemes that concentrate backup capacity on a few links. The advantage is demonstrated by a simulation of NSFnet comparing blocking probability of a distribution computed by this ILP vs. a Hamiltonian p-Cycle which is a capacity optimal way to protect the network.

WDM multistage interconnection networks architectures for enhancing supernetworks switching infrastructure

Abstract: Multistage Interconnection Networks (MINs) provide the required switching infrastructure for many shared-memory multiprocessor systems and telecommunication networks. The concept of Supernetworks is evolving in response to emerging computation and communication intensive applications. Supernetworks exploit parallelism in both computing resources and communication infrastructures by interconnecting several computing clusters via high-bandwidth communication links. Wavelength Division Multiplexing (WDM) technology provides the communication infrastructure for Supernetowrks by dividing the bandwidth of a single fiber into numerous channels that can be used independently. In this paper, we investigate several architectures for WDM MINs that enhance the Supernetworks switching infrastructure. Our objective is to propose a new architecture and to evaluate its hardware complexity by comparing it to other WDM MINs architectures.

Extensible optical access network enabling multistage protections and data aggregation based on tangent rings

Abstract: In this paper, an extensible optical access network architecture is proposed on the basis of multiple tangent single-fiber rings. With the proposed architecture, both multistage protections and data aggregation can be realized. Optical line terminal and remote nodes RNs can automatically switch to protection mode to overcome fiber failure occurring in both main ring MR and sub-rings SRs. The RNs, which are designed as tangent points, can realize wavelengths adding and dropping between MR and SRs, and they also can realize the network expansion conveniently and smoothly through adding more wavelengths. So, it is a good selection for next-generation large-scale access networks. Copyright © 2013 John Wiley & Sons, Ltd.

A load balanced approach of multicast routing and wavelength assignment in WDM networks

Abstract: Multicast routing and wavelength assignment MRWA deals with the problem of one-to-many communication in a wavelength division multiplexed optical fibre networks. As physical optical networks are equipped with finite number of optical channels in each fibre cable, throughput of the network is treated as a major performance issue. The aim of this work is to maximise throughput in a finite wavelength WDM network. As to establish multicast session a single message may need to split into multiple messages fanning out of a node, the node must contain costly splitters. This work also considers the cost of splitting at the split nodes while establishing a light-tree for a particular multicast session request. Here a load-balancing technique is used to optimise the optical channel requirements to establish a multicast connection. The algorithm proposed here is compared with standard all-shortest path algorithm combined with first-fit wavelength assignment for multicasting by simulation on various network topologies and different network configurations. The simulation result shows that our proposed algorithm performs much better than the standard one.

Dynamic connection provisioning with shared protection in IP/WDM networks

Abstract: Internet protocol IP traffic connections arrive dynamically at wavelength-division multiplexing WDM network edges with low data rates compared with the wavelength capacity, availability, and quality-of-service QoS constraints. This paper introduces a scheme to be integrated into the control and management plane of IP/WDM networks to satisfy the availability and QoS required for IP traffic connections bundled onto a single wavelength lightpath in WDM networks protected by shared-backup path protection SBPP. This scheme consists of two main operations: i routing multi-granular connections and traffic grooming policies, and ii providing appropriate shared protection on the basis of subscribers' service-level agreements in terms of data rate, availability, and blocking probability. Using the Markov chain process, a probabilistic approach is developed to conceive connection blocking probability models, which can quantify the blocking probability and service utilization of M:N and 1:N SBPP schemes. The proposed scheme and developed mathematical models have been evaluated in terms of bandwidth blocking ratio, availability satisfaction rate, network utilization, and connection blocking probability performance metrics. The obtained research results in this paper provide network operators an operational setting parameter, which controls the allocation of working and backup resources to dynamic IP traffic connections on the basis of their priority and data rate while satisfying their requirements in terms of bandwidth and availability. Copyright © 2013 John Wiley & Sons, Ltd.