A new framework for rapid restoration in optical mesh networks

A fundamental problem that needs to be addressed when designing survivable optical transport networks is the capability of these networks to quickly recover from element failures. Current restoration signaling is a two-phase messaging procedure between the sender and the receiver and depends heavily on the control message propagation delays during the recovery process and the optical cross-connect switching times. Offset time based restoration has been proposed to address [6] the impact of these network parameters and upper bound expressions have been derived. However, a closer investigation showed that as the network conditions change (e.g., increasing the number of wavelength channels per link) the benefits offered by the proposed framework would rapidly be depleted, and thereby rendering the argument of avoiding conventional restoration signaling inept. In this paper, we intend to re-use the same framework, however instead of using upper bound expressions to estimate the restoration times, we propose a more accurate model to estimate the offset time of each failed connection using a timedriven scheduling procedure. We show that propagation delays have very minimal impact on the network recovery times and switching delays are minimized whereas their accumulation along restoration routes is eliminated. We evaluate our proposal through simulation experiments and we show that by deploying a scheduling process, substantial restoration gain can be achieved under varying network conditions.