Abstract-Diversity coding is a network restoration technique which offers near-hitless restoration, while other state-of-theart techniques are significantly slower. Furthermore, the extra spare capacity requirement of diversity coding is competitive with the others. Previously, we developed heuristic algorithms to employ diversity coding structures in networks with arbitrary topology. This paper presents two algorithms to solve the network design problems using diversity coding in an optimal manner. The first technique pre-provisions static traffic whereas the second technique carries out the dynamic provisioning of the traffic ondemand. In both cases, diversity coding results in smaller restoration time, simpler synchronization, and much reduced signaling complexity than the existing techniques in the literature. A Mixed Integer Programming (MIP) formulation and an algorithm based on Integer Linear Programming (ILP) are developed for preprovisioning and dynamic provisioning, respectively. Simulation results indicate that diversity coding has significantly higher restoration speed than Shared Path Protection (SPP) and pcycle techniques. It requires more extra capacity than the p-cycle technique and SPP. However, the increase in the total capacity is negligible compared to the increase in the restoration speed.

Abstract-Link failures in wide area networks are common. To recover from such failures, a number of methods such as SONET rings, protection cycles, and source rerouting have been investigated. Two important considerations in such approaches are the recovery time and the needed spare capacity to complete the recovery. Usually, these techniques attempt to achieve a recovery time less than 50 ms. In this paper we introduce an approach that provides link failure recovery in a hitless manner, or without any appreciable delay. This is achieved by means of a method called diversity coding. We present an algorithm for the design of an overlay network to achieve recovery from single link failures in arbitrary networks via diversity coding. This algorithm is designed to minimize spare capacity for recovery. We compare the recovery time and spare capacity performance of this algorithm against conventional techniques in terms of recovery time, spare capacity, and a joint metric called Quality of Recovery (QoR). QoR incorporates both the spare capacity percentages and worst case recovery times. Based on these results, we conclude that the proposed technique provides much shorter recovery times while achieving similar extra capacity, or better QoR performance overall.

Abstract-Diversity coding is a network restoration technique which offers near-hitless restoration, while other state-of-theart techniques are significantly slower. Furthermore, the extra spare capacity requirement of diversity coding is competitive with the others. Previously, we developed heuristic algorithms to employ diversity coding structures in networks with arbitrary topology. This paper presents two algorithms to solve the network design problems using diversity coding in an optimal manner. The first technique pre-provisions static traffic whereas the second technique carries out the dynamic provisioning of the traffic ondemand. In both cases, diversity coding results in smaller restoration time, simpler synchronization, and much reduced signaling complexity than the existing techniques in the literature. A Mixed Integer Programming (MIP) formulation and an algorithm based on Integer Linear Programming (ILP) are developed for preprovisioning and dynamic provisioning, respectively. Simulation results indicate that diversity coding has significantly higher restoration speed than Shared Path Protection (SPP) and pcycle techniques. It requires more extra capacity than the p-cycle technique and SPP. However, the increase in the total capacity is negligible compared to the increase in the restoration speed.

The technique of diversity coding offers fast recovery against failures in networks while keeping spare capacity comparable to the alternative state-of-the art network restoration techniques. It provides near-hitless recovery when coding is performed on connections with the same destination node. When the coding structure is extended to cover the primary paths, diversity coding can achieve higher capacity efficiency than its conventional version and other restoration techniques. In this paper, we develop a systematic approach to implement the diversity coding structures for pre-provisioning with coding of the protection and primary paths. In addition, we present an algorithm to map these coding structures into arbitrary topologies. We present simulation results that show capacity efficiency of diversity coding.

Abstract-Network coding-based link failure recovery techniques provide near-hitless recovery and offer high capacity efficiency. Diversity coding is the first technique to incorporate coding in this field and is easy to implement over small arbitrary networks. However, its capacity efficiency is restricted by its systematic coding and high design complexity even though it has lower complexity than the other coding-based recovery techniques. Alternative techniques mitigate some of these limitations, but they are difficult to implement over arbitrary networks. In this paper, we propose a novel non-systematic coding technique and a simple design algorithm to implement the diversity coding-based (or network coding-based) recovery over arbitrary networks. The design framework consists of two parts. An ILP formulation for each part is developed. The simulation results suggest that both the novel coding structure and the novel design algorithm lead to higher capacity efficiency for near-hitless recovery. The new design algorithm is able to achieve optimal results in large arbitrary networks.

Abstract-Link failures in wide area networks are common and cause significant data losses. Mesh-based protection schemes offer high capacity efficiency but they are slow and require complex signaling. Additionally, real-time reconfiguration of a crossconnect threatens their transmission integrity. On the other hand, coding-based protection schemes are proactive. Therefore, they have higher restoration speed, lower signaling complexity, and higher transmission integrity. This paper introduces a codingbased protection scheme, named Coded Path Protection (CPP). In CPP, a backup copy of the primary data is encoded with other data streams, resulting in capacity savings. This paper presents an optimal and simple capacity placement and coding group formation algorithm. The algorithm converts the sharing structure of any solution of a Shared Path Protection (SPP) technique into a coding structure with minimum extra capacity. W e conducted quantitative and qualitative comparisons of our technique with the SPP and, another technique, known as pcycle protection. Simulation results confirm that the CPP is significantly faster than the SPP and p-cycle techniques. CPP incurs marginal extra capacity on top of SPP. Its capacity efficiency is lower than the p-cycle technique for dense networks but can be higher for sparse networks. In addition, unlike pcycle protection, CPP is inherently suitable for the wavelength continuity constraint in optical networks. I. INTRO DUCTIO NStudies show that reasons of failure in networks can be widespread. According to [1], cable cut rate per 1000 sheath miles per year is 4.39. That means on average a cable-cut occurs every three days per 30,000 fiber miles. These numbers are consistent with the FCC data, summarized as 13 cuts per year for every 1,000 miles of fiber and 3 cuts per year for every 1,000 miles of fiber for metro and long haul networks respectively [2]. As stated in [3], 70% percent of the unplanned network failures affect only single links. For this reason, in this paper, we focused on single link failure recovery.1+1 and 1:1 automatic protection switching were early attempts of path-based protection mechanisms but were dropped due to low capacity efficiency. Mesh-based protection schemes attracted attention due to their high capacity efficiency but suffered from low speed. SPP [4] is a widely recognized meshbased path protection technique. It specifies two link-disjoint paths for each connection and reroutes the traffic over the protection path if the primary path fails.Reference [5] introduced the concept of a p-cycle in order to achieve both fast restoration and low spare capacity percentage. Fundamentally, a p-cycle is a mixture of ring-type protection and link-based protection. Its performance is similar to SPP in terms of resource utilization and similar to link-based protection in terms of restoration time. In the case of a failure in a link protected by the cycle, the affected traffic is rerouted over the spare capacity in the healthy parts of the p-cycle.The p-cycle appro...

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