Design of survivable IP-over-WDM networks

In IP-over-WDM networks, protection can be offered at the optical layer or at the electronic layer. While optical protection allows fast restoration in case of single link failures (due to, i.e., cable cuts), it does not offer recovery from IP layer failures (e.g., IP router failures). So both optical protection and IP restoration are needed, and requires coordination in order to avoid duplicated protection or multi-layer contention issues.