Protecting against link failures in communication networks is essential to increase robustness, accessibility, and reliability of data transmission. Recently, network coding has been proposed as a solution to provide agile and cost efficient network protection against link failures, which does not require data rerouting, or packet retransmission. To achieve this, separate paths have to be provisioned to carry encoded packets, hence requiring either the addition of extra links, or reserving some of the resources for this purpose. In this paper, we propose network protection codes against a single link failure using network coding, where a separate path using reserved links is not needed. In this case portions of the link capacities are used to carry the encoded packets. The scheme is extended to protect against multiple link failures and can be implemented at an overlay layer. Although this leads to reducing the network capacity, the network capacity reduction is asymptotically small in most cases of practical interest. We demonstrate that such network protection codes are equivalent to error correcting codes for erasure channels. Finally, we study the encoding and decoding operations of such codes over the binary field.
@cite_11 , the author introduced a 1+N protection model in optical mesh networks using network coding over p-cycles. The author suggested a model for protecting @math connections from a set of sources to a set of receivers in a network with @math connections, where one connection might fail. The suggested model can protect against a single link failure in any arbitrary path connecting a source and destination.
@cite_11
2040468540 2123610191 2169892591 2160995598
p-Cycles have been proposed for pre-provisioned 1:N protection in optical mesh networks. Although the protection circuits are preconfigured, the detection of failures and the rerouting of traffic can be a time consuming operation. Another survivable mode of operation is the 1+1 protection mode, in which a signal is transmitted on two link disjoint circuits, and the destination chooses the strongest of the two signals, hence recovery from failures is instantaneous. The disadvantage is the large number of protection circuits. In this paper we introduce a new concept in protection: 1+N protection, in which a p-Cycle can be used to protect a number of bidirectional connections. Data from different circuits are combined using network coding, which can be implemented in a number of technologies. The maximum outage time under this protection scheme is limited to no more than twice the p-Cycle propagation delay. In [1], the author introduced a strategy to use network coding on p-Cycles in order to provide 1+N protection for straddling connections and links against single link failures in mesh optical networks. In this paper we extend the work in [1] and introduce a GMPLS-based implementation of this strategy for link protection, that is also used to protect on-cycle links. We refer to this scheme as hybrid 1+N protection, since some data units are transmitted without being combined with other data units. The strategy uses a combination of GMPLS standard label switched paths (LSP) for protecting on-cycle links, and modified LSPs, which we refer to as label switched cycles (LSC), for protecting straddling links. The strategy does not have to explicitly detect failures, but rather detects the absence of data units. Destinations receive backup copies of packets within no more than the p-Cycle propagation delay for on-cycle link failures, and no more than the sum of the propagation delays of the p-Cycle and the longest straddling link for straddling link failures. The implementation details of this strategy are presented, and the cost of implementation, in terms of link usage is evaluated and is shown to be modest. This scheme can therefore provide protection at higher layers, at a speed that is comparable to that achieved at the physical layer, but at a much reduced cost, while being flexible, and requiring less involvement from the management and control planes. Recently, physical layer security in the optical layer has gained significant traction. Security treats in optical networks generally impact the reliability of optical transmission. Linear Network Coding (LNC) can protect from both the security treats in form of eavesdropping and faulty transmission due to jamming. LNC can mix original data to become incomprehensible for an attacker and also extend original data by coding redundancy, thus protecting a data from errors injected via jamming attacks. In this paper, we study the effectiveness of LNC to balance reliable transmission and security in optical networks. To this end, we combine the coding process with data flow parallelization of the source and propose and compare optimal and randomized path selection methods for parallel transmission. The study shows that a combination of data parallelization, LNC and randomization of path selection increases security and reliability of the transmission. We analyze the so-called catastrophic security treat of the network and show that in case of conventional transmission scheme and in absence of LNC, an attacker could eavesdrop or disrupt a whole secret data by accessing only one edge in a network. As the operation of our fiber-optic backbone networks migrates from interconnected SONET rings to arbitrary mesh topology, traffic grooming on wavelength-division multiplexing (WDM) mesh networks becomes an extremely important research problem. To address this problem, we propose a new generic graph model for traffic grooming in heterogeneous WDM mesh networks. The novelty of our model is that, by only manipulating the edges of the auxiliary graph created by our model and the weights of these edges, our model can achieve various objectives using different grooming policies, while taking into account various constraints such as transceivers, wavelengths, wavelength-conversion capabilities, and grooming capabilities. Based on the auxiliary graph, we develop an integrated traffic-grooming algorithm (IGABAG) and an integrated grooming procedure (INGPROC) which jointly solve several traffic-grooming subproblems by simply applying the shortest-path computation method. Different grooming policies can be represented by different weight-assignment functions, and the performance of these grooming policies are compared under both nonblocking scenario and blocking scenario. The IGABAG can be applied to both static and dynamic traffic grooming. In static grooming, the traffic-selection scheme is key to achieving good network performance. We propose several traffic-selection schemes based on this model and we evaluate their performance for different network topologies.