Survey on Dependable IP over Fiber Networks

This paper gives a survey of the techniques for failure location, protection and restoration in IP over optical fiber networks. The first part of the paper reviews failure location algorithms at the optical and the IP layers. We classify the failure location algorithms at the optical layer into two main categories: the model based approach, that builds an abstract model of the network and uses this model to diagnose failures, and the learning based approach, that views the network as a black box and diagnoses failures using a set of rules obtained either by learning or by the expertise of the human manager. At the IP layer, we focus on the location of one of the main sources of failure: lossy links. The lossy link location algorithms can also be classified into two categories: the correlation approach, that requires strong correlation between monitoring packets, and the simple tomography approach, that requires some knowledge of the distribution of lossy links. The second part of the paper describes the main strategies that ensure survivability in IP-over-fiber networks. After a failure, traffic can be restored either at the optical layer or at the IP layer. Protection at the optical layer amounts to dedicate some lightpaths to reroute the traffic disrupted by the failure. Restoration at the IP layer eliminates the need to set up back-up optical paths, but requires to map the IP layer on the optical layer in a survivable way. We describe the most common approaches achieving this.