<p><a href="http://www.osa-jon.org/virtual_issue.cfm?vid=16">Feature Issue on High Availability in Optical Networks</a></p> The protected network layer packet redundancy scheme (P-NLPRS), which is a novel approach to providing 1+1 path protection functionality in optical packet switching (OPS) networks, is presented. Traditional 1+1 path protection protects data by transmitting two identical copies of each packet over two node- and link-disjoint paths between an ingress and egress node in a network. With the P-NLPRS, a packet set consisting of k−1 data packets and 1 redundancy packet is transmitted over k node- and link-disjoint paths between an ingress and egress node in the OPS network. The P-NLPRS is especially attractive for OPS, since, in addition to providing 1+1 path protection functionality, it may be utilized to combat packet loss due to contentions. An analytical framework suitable for evaluating the cost of providing 1+1 path protection is presented, along with an analytical model of the P-NLPRS. A quantitative cost study shows that the P-NLPRS can provide 1+1 path protection functionality with 33% to 91% of the cost required by traditional 1+1 path protection, depending on the cost model and the network topology.
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