A construction of 1-to-2 shared optical buffer queue with switched delay lines

Abstract

Optical buffering is fundamental to contention resolution in optical networks. The current works on this line mainly focus on the emulation of dedicated input/output buffer queue by using switched fiber delay lines (SDL). It is notable that the shared buffer queue, where a common buffer pool is shared by all the input/output ports of a switch, has the potential to significantly reduce the overall buffer capacity requirement. As far as we know, however, no related work is available yet on the exact emulation of a shared optical buffer queue with SDLs. In this paper, we focus on the design of first in first out (FIFO) shared optical buffer queue based on the optical feedback SDL construction. The construction considered consists of an (M + 2) x (M + 2) switch fabric and M fiber delay lines FDL <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> , . . ., FDL <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</sub> , where FDL <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> connects the i <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> output of the switch fabric with its i <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> input. We show that by setting the length of FDL <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> as min(M + 1 - i, i), i = 1, . . . , M, such a construction can actually work as an 1-to-2 shared buffer queue. We then extend this emulation to the more general N-to-2 case.