The demand for increasing capacity in service provider's networks has led to the development of different transport technologies such as PDH, SDH/SONET, WDM/DWDM, OTN, Ethernet, MPLS-TP etc. which support different types of traffic requirements. Transport networks get augmented due to the surge in capacity requirements. The need for shorter time to provision capacity along with the continuous growth in transport networks typically result in sub-optimal utilization of network resources. Optimization involves consideration of the existing traffic demands for services already provisioned and providing alternate paths and resources based on some global metrics. In multi-layer multi-technology transport networks, this work focuses on optimization of capacity consumed globally for the complete network instead of optimizing capacity in each layer network independently so that it could result in significant benefits in utilization of the existing network. Techniques like traffic grooming across layers and topologies between every pair of nodes by creating tunnels or bearers are used to find the optimum capacity usage. In terms of total capacity used and the number of flows or cross-connections created, the performance of the proposed approach is compared with the provisioning simulated for service requests one-by-one and it is found that the grooming based approach results in lower capacity utilization and number of flows or cross-connections created. © 2019 IFIP.