Logical Network Mapping With Content Connectivity Against Multiple Link Failures in Optical Metro Networks

Network connectivity has been the traditional metric for network survivability against failures. In case of a disaster, network connectivity may not always be guaranteed due to multiple link failures. With the shifting service paradigm towards cloud computing/storage, some network services can still be provided if a content replica is available in all disconnected network segments. As a result, content connectivity has been introduced as an additional metric for network survivability under disasters. Content connectivity is defined as the reachability of content from every node in a logical topology under a given failure scenario. In this work, we investigate the content-connectivity problem in optical metro networks in the case of multiple (n) link failures. We consider the problem of mapping a logical topology over an optical metro network such that every node in the logical topology can reach at least one data center hosting the content after n-link failures. We formulate the problem as an integer linear program to minimize total network resource usage. We provide a cost comparison between content connectivity and network connectivity under typical failure scenarios.