Stability Analysis of a Two-stage Optical Buffer

In optical packet/burst switching, fiber delay line (FDL) optical buffers provide an effective means of contention resolution. In many implementations, a single-stage buffer is assumed. In this contribution, however, we analyze a multistage setting, with the second stage consisting of only a single small delay line. For the stability analysis, we take the analysis of a non-equidistant single-stage buffer as a starting point, adding so-called exceptions to cover the two-stage case. Methodologically, we rely on probability generating functions (pgf's).