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: 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.
@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.