Design-Dimensioning Model for Transparent WDM Packet-Switched Irregular Networks

A detailed analytical traffic model for all-optical wavelength division multiplexing (WDM) photonic packet-switched networks is presented and the requirements for buffer size and link dimensions are analyzed. This paper shows that due to the topology, packets may generate traffic bottlenecks produced by a tendency of the routing scheme to send packets with different destinations through preferred paths. This effect increases the traffic load and, hence, the probability of blocking at the output links of specific routers in the network and, therefore, a large buffer depth is required or an increment in the number of fibers per link. Three router architectures are analyzed and it is shown that WDM all-optical router architectures with shared contention resolution resources are the best candidates to reduce hardware volume and cost of all-optical networks. It is shown that routers with a bank of completely shared wavelength converters (WCs) require a fraction of WCs compared to router architectures that use a WC per wavelength. This fraction depends on the location of the router, the network topology, and the traffic load in the network. However, in general terms, about 50% to 90% of WCs can be saved by architectures with shared wavelength-conversion resources. Also, it is shown that limited wavelength conversion degrees d = 8 and d = 10 in packet-switching routers with 16 and 32 wavelengths give the same probability of packet loss performance as full wavelength conversion.