Overlay Protection Against Link Failures Using Network Coding

This paper introduces a network coding-based protection scheme against single and multiple link failures. The proposed strategy ensures that in a connection, each node receives two copies of the same data unit: one copy on the working circuit, and a second copy that can be extracted from linear combinations of data units transmitted on a shared protection path. This guarantees instantaneous recovery of data units upon the failure of a working circuit. The strategy can be implemented at an overlay layer, which makes its deployment simple and scalable. While the proposed strategy is similar in spirit to the work of Kamal '07 & '10, there are significant differences. In particular, it provides protection against multiple link failures. The new scheme is simpler, less expensive, and does not require the synchronization required by the original scheme. The sharing of the protection circuit by a number of connections is the key to the reduction of the cost of protection. The paper also conducts a comparison of the cost of the proposed scheme to the 1+1 and shared backup path protection (SBPP) strategies, and establishes the benefits of our strategy.Comment: 14 pages, 10 figures, accepted by IEEE/ACM Transactions on Networkin

Protection against link errors and failures using network coding

We propose a network-coding based scheme to protect multiple bidirectional unicast connections against adversarial errors and failures in a network. The network consists of a set of bidirectional primary path connections that carry the uncoded traffic. The end nodes of the bidirectional connections are connected by a set of shared protection paths that provide the redundancy required for protection. Such protection strategies are employed in the domain of optical networks for recovery from failures. In this work we consider the problem of simultaneous protection against adversarial errors and failures. Suppose that n_e paths are corrupted by the omniscient adversary. Under our proposed protocol, the errors can be corrected at all the end nodes with 4n_e protection paths. More generally, if there are n_e adversarial errors and n_f failures, 4n_e + 2n_f protection paths are sufficient. The number of protection paths only depends on the number of errors and failures being protected against and is independent of the number of unicast connections.Comment: The first version of this paper was accepted by IEEE Intl' Symp. on Info. Theo. 2009. The second version of this paper is submitted to IEEE Transactions on Communications (under minor revision). The third version of this paper has been accepted by IEEE Transactions on Communication

Energy Efficient Core Networks Using Network Coding

In this paper we investigate the use of network coding to improve energy efficiency of core networks. A mixed integer linear programming model is developed to optimize routing in network coding enabled non-bypass IP/WDM networks considering unicast traffic flows. We quantify the power savings obtained by implementing network coding. The results show that network coding can improve the energy efficiency of non-bypass IP/WDM networks by up to 33% compared to conventional architectures

Protection against link errors and failures using network coding in overlay networks

We propose a network-coding based scheme to protect multiple bidirectional unicast connections against adversarial errors and failures in a network. The end nodes of the bidirectional connections are connected by a set of shared protection paths that provide the redundancy required for protection. Suppose that ne paths are corrupted by an omniscient, computationally unbounded adversary. Under our proposed protocol, the errors can be corrected at all the end nodes with 4ne protection paths. More generally, if there are ne adversarial errors and nƒ failures, 4ne + 2nƒ protection paths are sufficient. The number of protection paths only depends on the number of errors and failures being protected against and is independent of the number of unicast connections

Improving reliability in multi-layer networks with Network Coding Protection

© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.A major concern among network providers is to endow their networks with the ability to withstand and recover from failures. In recent years, there is a trend in network research referred to as Network Coding Protection (NCP). NCP combines the use of network coding techniques with a proactive protection scheme with the aim of improving network reliability. Although today's network backbone is a multi-layer network formed by the convergence of IP/MPLS and Optical technologies, the information available in the literature related to the performance of NCP schemes in multi-layer network scenarios is yet scarce. In this paper, we propose a novel NCP scheme referred to as DPNC+. The novelty of DPNC+ is that it exploits cross-layer information in order to improve the reliability of multi-layer (IP/MPLS over Optical) networks against link failures. Our evaluation results show that reduction up to 50% -related to protection cost- can be obtained when using the proposed scheme compared to conventional proactive protection techniques.This work was supported by the Spanish Ministry of Economy under contract TEC2012-34682, and the Catalan Research Council (CIRIT) under contract 2009 SGR1508.Peer ReviewedPostprint (author's final draft

On the multiple unicast capacity of 3-source, 3-terminal directed acyclic networks

We consider the multiple unicast problem with three source-terminal pairs over directed acyclic networks with unit-capacity edges. The three $s_i-t_i$ pairs wish to communicate at unit-rate via network coding. The connectivity between the $s_i - t_i$ pairs is quantified by means of a connectivity level vector, $[k_1 k_2 k_3]$ such that there exist $k_i$ edge-disjoint paths between $s_i$ and $t_i$. In this work we attempt to classify networks based on the connectivity level. It can be observed that unit-rate transmission can be supported by routing if $k_i \geq 3$, for all $i = 1, \dots, 3$. In this work, we consider, connectivity level vectors such that $\min_{i = 1, \dots, 3} k_i < 3$. We present either a constructive linear network coding scheme or an instance of a network that cannot support the desired unit-rate requirement, for all such connectivity level vectors except the vector $[1~2~4]$ (and its permutations). The benefits of our schemes extend to networks with higher and potentially different edge capacities. Specifically, our experimental results indicate that for networks where the different source-terminal paths have a significant overlap, our constructive unit-rate schemes can be packed along with routing to provide higher throughput as compared to a pure routing approach.Comment: To appear in the IEEE/ACM Transactions on Networkin

Secure Optical Networks Based on Quantum Key Distribution and Weakly Trusted Repeaters

In this paper we explore how recent technologies can improve the security of optical networks. In particular, we study how to use quantum key distribution (QKD) in common optical network infrastructures and propose a method to overcome its distance limitations. QKD is the first technology offering information theoretic secret-key distribution that relies only on the fundamental principles of quantum physics. Point-to-point QKD devices have reached a mature industrial state; however, these devices are severely limited in distance, since signals at the quantum level (e.g. single photons) are highly affected by the losses in the communication channel and intermediate devices. To overcome this limitation, intermediate nodes (i.e. repeaters) are used. Both, quantum-regime and trusted, classical, repeaters have been proposed in the QKD literature, but only the latter can be implemented in practice. As a novelty, we propose here a new QKD network model based on the use of not fully trusted intermediate nodes, referred as weakly trusted repeaters. This approach forces the attacker to simultaneously break several paths to get access to the exchanged key, thus improving significantly the security of the network. We formalize the model using network codes and provide real scenarios that allow users to exchange secure keys over metropolitan optical networks using only passive components. Moreover, the theoretical framework allows to extend these scenarios not only to accommodate more complex trust constraints, but also to consider robustness and resiliency constraints on the network.Comment: 11 pages, 13 figure

Combined Network and Erasure Coding Proactive Protection for Multiple Source Multicast Sessions

Due to the increase in the density and multitude of online real time applications involving group communication which require a certain degree of resiliency, proactive protection of multicast sessions in a network has become prominent. The backbone network providing such a service hence needs to be robust and resilient to failures. In this thesis, we consider the problem of providing fault tolerant operation for such multicast networks that have multiple sources and need to deliver data to pre-defined set of destinations. The data is assumed to be delivered in a highly connected environment with a lot of nodes, e,g., a dense wireless network. The advent of network coding has enabled us to look at novel ways of providing proactive protection. Our algorithm combines network and erasure coding to present a scheme which can tolerate predefined amount of failures in the paths from the sources to the destinations. This is accomplished by introducing redundancy in the data sent through the various paths. Network coding seeks to optimize the resource usage in the process. For sources that cannot meet the constraints of the scheme, protection is provided at the cost of reduced throughput