The strict-sense nonblocking elastic optical switch

Abstract

In this paper, we address the problem of the strictsense nonblocking operation of an elastic optical switch. Elastic optical switches are used as nodes in elastic optical networks (EONs), where fine granular frequency slots or flexible grids are used in opposite to the traditional optical networks, where fixed grids are used. The switch architecture considered in this paper consists of waveband converting switches in input and output stages, while in the center stage there is only one wavelength selective space switch without wavelength conversion capabilities. We derive the number of frequency channels k needed in interstage links to ensure the nonblocking operation of the switch when input and output links have n frequency channels and a frequency slot of one connection is not greater than m frequency channels. Both, necessity and sufficient conditions are proved.

Rearrangeable $$2 \times 2$$ elastic optical switch with two connection rates and spectrum conversion capability

“…The strict-sense nonblocking (SSNB) conditions (necessary and sufficient) for WSW1 were provided and proved in a previous study [12]. In SSNB switching fabrics, we can establish a connection from an idle set of FSUs at any input fiber to an idle set of FSUs at a requested output fiber regardless of how the other connections are established.…”

“…In general, the WSW1 switching architecture has r input and output fibers as described in detail by [12]. In the present study, we mainly consider switching fabrics where r = 2 , and we then show how the proposed algorithms can be used in case when r > 2 .…”

“…Each BV-WS in the first stage has one input fiber with n FSUs ( n = 5 in the example) and one output fiber with k FSUs, whereas each BV-WS in the third stage has one input fiber with k FSUs and one output fiber with n FSUs. The internal architectures of the BV-WSs and BV-SS were described by [12]. The switching fabric serves m-slot connections, where m is limited to two values of m 1 and m 2 , and m 2 > m 1 .…”

“…Several architectures have been proposed for these switching nodes in previous studies [7][8][9][10], which were surveyed briefly [11]. One of these switching fabric architectures is the wavelength-space-wavelength (W-S-W) switching fabric [12], which is referred to as WSW1 [10]. This architecture is also considered in the present study.…”

Defragmentation in W-S-W Elastic Optical Networks

“…Therefore, the use of different defragmentation techniques allows to set up some, or sometimes all connections which normally will not be set up due to improper utilization of the spectrum. [6] and Space-Wavelength-Space (S-W-S) [7] were proposed. In this paper, two instances of the W-S-W architecture are considered, called WSW1 and WSW2, respectively [8].…”