Analysis of Sub-Wavelength Traffic Grooming Efficiency in Optical Mesh Networks

Two-tier network architectures ([4],[5]) combine the benefits of STS-1 and STS-48 switches by using an upper tier of STS-48 switches for routing and restoration and a lower tier of STS-1 switches for grooming efficiency. A partial two-tier architecture, where STS-1 switches are restricted to a subset of the network nodes, has been shown in [3] to closely match the grooming benefits of a full lower STS-1 tier. We furnish a detailed upper bound analysis of how the fragmented/unused capacity in STS-48 channels (fragmentation loss) varies with the grooming capability of a network for arbitrary traffic scenarios. We show that the upper bounds derived in this paper are in agreement with results obtained using efficient routing and grooming algorithms discussed in [3].