Design strategies for survivable Grouped Routing Entity (GRE)-based optical networks

In bandwidth abundant optical networks, the Grouped Routing Entity (GRE) concept is a cost-efficient alternative used instead of waveband routing. It offers all the benefits of the waveband routing (i.e., reduced number of ports), without using expensive wavelength cross connects (WXCs) required in hierarchical optical networks. In fact in a GRE-based optical network wavelength channel add/drop operations are accomplished via Wavelength Selective Switches (WSS) or with optical couplers. The objective of this paper is to further investigate the benefits of GRE-based optical networks in a scenario where survivability is required. In this paper a dedicated protection scheme is proposed, where wavelength paths are efficiently routed using mostly disjoint working and backup GRE pipes (i.e., working and backup pipes are allowed to share some common nodes along their paths). Numerical experiments demonstrate that significant hardware scale reduction at the switching nodes can be obtained by using the proposed network design algorithm.