Electronic architectures of optical slot switching nodes (2013)

An optical slot switching ring network called POADM (packet optical add-drop multiplexers) was formerly proposed as a flexible solution to carry time-varying traffic, for instance in metro networks, with a good energy efficiency which is enabled by optical transparency. 

In this paper, we propose several architectures for the electronic side of optical slot switching nodes. Those architectures increase the flexibility with which a client, attached to a node, can access the transport medium, through the addition of electronic switches, working either at client frame or at slot granularity; located at either transmission, reception, or both sides of a node, thereby decreasing traffic latency, at the expense of increased node cost and/or energy consumption. 

This paper focuses on the performance aspect only. We assess and compare the performance (in terms of client frame queuing delay) of these node architectures with simulations; some results are also backed analytically. The utilization of slot granularity switching enables load balancing across the transport channels, while, the node architecture with client frame switching additionally permits flow aggregation, resulting in lower queuing delay. 

The lowest queuing delay is achieved by the architecture embedding client frames granularity switches at both Tx and Rx sides, while the absence of electrical switches leads to the worst performance, but presents the advantage of lower cost and consumption with respect to the other architectures. The utilization of client frame granularity switch at Tx or Rx presents intermediate performances.