In large multi-domain networks, topology aggregation - besides assuring scalability - has a side-effect as it introduces undesired inaccuracies in the routing information. Such inaccuracy affects the efficiency of routing. In this paper, with the application of a threshold-based aggregation model, the relation between scalability and routing efficiency has been examined by evaluating two different types of efficiency-related functions. By means of simulation, a trade-off quality between scalability and routing efficiency has been revealed. By introducing a penalty method for inaccuracy compensation, routing efficiency has shown a considerable improvement. Finally, a few possible ways of (conceptual) realization have been discussed for the ASON/GMPLS framework.