Guaranteeing packet order in IBWR optical packet switches with parallel iterative schedulers

The input-buffered wavelength-routed (IBWR) switch is a scalable switch fabric for optical packet switching (OPS) networks. In synchronous operation, when optical packets are of a fixed duration and aligned at switch inputs, the scheduling of this architecture can be characterised by a type of bipartite graph matching problem. This challenges the design of feasible algorithms in terms of implementation complexity and response time. A previous work presented and evaluated the insistent parallel desynchronized block matching (I-PDBM) algorithm for the IBWR switch. I-PDBM is a parallel iterative scheduler with a good performance and a simple hardware implementation. However, the algorithm does not maintain the packet sequence. In this paper, we present the I-PDBM algorithm with packet ordering (OI-PDBM), which prevents mis-sequencing and behaves as I-PDBM in terms of delay, buffer requirements and convergence speed.