In packet-optical integrated transport nodes for metropolitan networks, the wavelength data rate of the transponders has increased quickly to 10, 40, and 100 Gbps to reduce the cost of the transported bit. Meanwhile, the majority of the client data rate in routers and packet switches are still operating at 1, 2.5, and 10 Gbps. In this scenario, the introduction of optical transport network (OTN) switching technology enables an efficient wavelength bandwidth utilization and reduces the number of wavelengths, leading to reduced network costs. It has been shown that the use of integrated OTN/WDM switch architecture is cost effective because it reduces the number of short-reach client interfaces. The OTN/WDM also reduces the rack space and the power consumption compared to an architecture that uses a reconfigurable optical add–drop multiplexer and a separate standalone OTN switch or one that uses back-to-back muxponder connections to perform manual grooming. We introduce and investigate the performance of a new integrated OTN/WDN switching architecture in which the number of OTN switches is minimized. We propose an analytical model for the evaluation of the switch-blocking probability when two different OTN switch assignment policies are used. We show how the number of OTN switches can be reduced if a suitable dimensioning procedure is performed and depending on the traffic percentage needing OTN switching. As an example, if traffic is less than 45%, then the new proposed OTN/WDM switching architecture allows for 25% savings in OTN switching resources in the case of a switch with 4 input/output lines, 48 wavelengths, and OTN switches.
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