Post-restoration strategies in ASTN-based optical mesh networks

Summary form only given. Automatically Switched Transport Network (ASTN) has many capabilities (such as dynamic connection/routing) that make it attractive for traffic engineering and optimization of next generation large scale optical mesh backbones. ASTN enabled mesh networks to offer a wide spectrum of restoration schemes, each tailored to a connection-specific Class Of Service (COS), ranging from Layer 1 protection for highest-grade connection services down to unprotected pre-emptable schemes. In this context, most of the previous studies, dealing with mesh restoration have focused on restoration mechanisms for traffic recovery, following failures. However, post-restoration procedures have not been thoroughly investigated and these are crucial in mesh environments due to the sharing of spare back up paths and the requirement not only to guarantee restoration against the first failure, but also to maximize restorability against subsequent failures in the network. We highlight the need and advantages of post-restoration procedures in next generation ASTN-based optical mesh networks in terms of achieving higher bandwidth efficiency, faster restoration time and higher availability. These are among the key attributes that need to be taken into account when designing a mesh network. We also explore the various post-restoration strategies that network designers can envisage, taking into account the coexistence of several shared back-up path restoration schemes such as dynamic path restoration, pre-computed (preplanned) path restoration, link-level and path-level restoration schemes.