Design and control of next generation distribution frames

In today's access networks, the permutation of circuits connecting the subscriber lines to Plain Old Telephone Service (POTS) and to Digital Subscriber Line Access Multiplexers (DSLAMs) occurs in the Main Distribution Frame (MDF) and is still manually configured. However, new market regulations and new policies adopted by operators require increasingly more frequent permutations, making the manual configuration activity particularly expensive. Very recently, Automated MDFs (AMDFs) have been developed to provide inexpensive and almost real-time switching capability. Our study, based on more than 50 years of research activities on architectures for circuit switching, is focused on overcoming the limits of classical architectures. In fact, strictly non-blocking multistage networks are too expensive, as a consequence of the large number of ports they require (sometimes exceeding 100,000). In addition, rearrangeable multistage networks can temporarily interrupt active circuits, affecting the performance of ADSL subscriber lines. As a possible solution to these problems, we propose the design of AMDFs based on Non-Interruptive Rearrangeable (NIR) networks. We show how to optimize the routing control to minimize the setup time of a circuit and to exploit output grouping. We believe that the solution described above is not only relevant for the theory of multistage interconnection networks, but also for the design and operation of large AMDFs. (C) 2012 Elsevier B.V. All rights reserved.