Wavelength converter and fiber delay-line sharing in WDM optical packet switches: dimensioning and performance issues

Abstract

In this paper, two switch models -- MOD1, employs a set of nondegenerate fiber delay-lines (FDLs) shared among the input lines, and MOD2, employs a set of degenerate FDLs and tunable wavelength converters (TOWCs) shared among the input lines, are proposed to handle contention. We demonstrate that for a prefixed packet loss probability constraints, e.g., 10-6, and for nonbursty traffic, if the wavelengths per fiber is no less than 8, a very small number of FDLs is sufficient to obtain a reasonable packet loss probability for both models, i.e., without the need to use TOWCs for MOD2, used for MOD1 equals to those of the FDLs and TOWCs used for MOD2, MOD2 performs much better than MOD1 even if no TOWC is used. With the increase of the average burst length, the number of TOWCs needed by MOD2 needs to be increased so as to maintain a reasonable packet loss probability. However, even for the traffic with high degree of burstness, MOD2 is still a cost effective and robust solution.