Design of a Meta-Mesh of Chain Sub-Networks Enhancing the Attractiveness of Mesh-Restorable.pdf

W. D. Grover, J. Doucette, Design of a Meta-Mesh of Chain Sub-Networks…, IEEE Journal on Selected Areas in Communications (JSAC), Special Issue on WDM-based Network Architectures, in press, 1st Quarter 2002. Final Revision 15/August/2001 0 Design of a Meta-Mesh of Chain Sub-Networks: Enhancing the Attractiveness of Mesh-Restorable WDM Networking on Low Connectivity Graphs Wayne D. Grover, Senior Member IEEE and John Doucette, Student Member IEEE TRLabs, #800 10611 - 98 Avenue, Edmonton, Alberta, Canada T5K 2P7 and Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada {grover, doucette}@edm.trlabs.ca Abstract – We have developed a refinement to existing methods to increase the capacity efficiency of span-restorable mesh networks on sparse facility graphs. The new approach views the network as a “meta-mesh of chain sub-networks.” This makes the prospect of WDM mesh networking more economically viable than with previous mesh-based design where the average nodal degree is low. The meta-mesh graph is a homeomorphism of the complete network in which edges are either direct spans or chains of degree-2 nodes. The main advantage is that loop-back type spare capacity is provided only for the working demands that originate or terminate in a chain, and not for the entire flow that crosses a chain. The transiting (“express”) flows are entirely mesh- protected within the meta-mesh graph which is of higher average degree and hence efficiency for mesh restoration, than the network as a whole. Nodal equipment savings also arise from the grooming of express lightpaths onto the logical chain-bypass span. Only the meta-mesh nodes need optical cross-connect functionality. Other sites use OADMs and/or glassthroughs. The resultant designs comprise a special class of restorable network that is intermediate between pure span restoration and path restoration. Most of the efficiency of path restoration is achieved, but with a span restoration mec