Design and control of next generation distribution frames

Abstract

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 (AMDF) 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.

Scalable crossbar network: a non-blocking interconnection network for large-scale systems

“…According to Eqs. (41) to (47), the results of system failure rate analysis as a function of time for different network sizes of 8, 128, and 1,024 are summarized in Tables 5, 6, and 7, respectively. In Tables 5, 6, and 7, the results of the system failure rate analysis are given for various times from 1,000 to 8,000 h. As the results demonstrate, the SCN achieves the lowest failure rate among other networks for all network sizes of 8, 128, and 1,024.…”

“…In this network, the path length can vary between Although this structure can satisfy the scalability parameter, it has a major disadvantage compared to typical crossbar network, higher hardware cost. Cost of an interconnection network can be calculated according to the number of crosspoints within a switch [20,33,39,47]. Therefore, since there are (N 2 ) crosspoints on a crossbar network, its cost is equal to (N 2 ).…”

“…2, the cost of a network can be calculated by taking the number of crosspoints within a switching element and by the number of switching elements within the network [20,33,39,45,47] into account. Therefore, cost of two networks of crossbar and MCN is equal to (N 2 ) and (4N 2 ), respectively.…”

“…(b) Usually it needs a suitable mechanism or control for assigning the connections. Also, the mechanism or control in Clos network is too complex [14,30,[45][46][47][48]. In routing a circuit in a Clos network, the only free decision is at the first stage switch, where any of the m middle switches can be chosen as long as the link to that middle switch is available.…”