Dimensioning of FDL Buffers for Optical Burst Switching Nodes

Abstract

Optical burst switching (OBS) is a promising candidate for a more dynamic optical layer in the context of IP over WDM. Although buffering is not mandatory for the functionality of OBS, even simple FDL buffers can improve burst loss probability. In this paper, we first discuss principal buffer architectures and reservation schemes for fiber delay line (FDL) buffers. Then, we investigate key design parameters of FDL buffers like FDL delay, buffer architecture and total number of buffer ports. Finally, we introduce and evaluate strategies for distributing a given number of buffer ports over all FDL's of a feed-forward buffer.

Research in optical burst switching within the e-Photon/ONe network of excellence

“…It has been shown that even FDL buffers with rather simple functionality and low technological requirements can improve OBS performance significantly [8,13,2,14].…”

“…Consequently, all FDLs used for contention resolution have to be shorter than a typical EDFA span of 80 km which limits the maximum FDL delay to 266 µs (c = 2 × 10 8 m/s). Previous work showed that FDL delays should be in the order of a few mean burst durations in order to be efficient [13,8]. In a FDL buffer with 4 FDLs, e.g., a delay of 8 mean burst durations for the longest FDL is a good choice.…”

“…This is called the PreRes scheme as the output is reserved prior to the burst entering the buffer. An alternative strategy is PostRes, in which case an output reservation is requested after the burst has entered the FDL but before it leaves the buffer [13]. In PostRes, all blocked bursts are buffered if buffer space is available.…”

ARTEMIS: 40-gb/s all-optical self-routing node and network architecture employing asynchronous bit and packet-level optical signal processing

“…Data channel contention occurs when two or more packets/bursts are simultaneously destined to the same output port on the same wavelength. Standard methods to resolve this issue have been space deflection (deflection routing) [33]- [35], time deflection (buffering) [36], [37], and wavelength conversion [38].However, deflection routing affects the network load and cannot guarantee packet arrival in the correct order, time deflection is impractical due to the lack of scalable optical buffers while wavelength conversion raises the complexity of the node and thus the hardware cost. Moreover, none of the above policies are suitable for the all-optical self-router features of the ARTEMIS switching paradigm.…”

Modeling and Analysis of a Shared Channel Architecture for Performance Improvement in Optical Burst Switched Networks

“…Many contention resolution schemes for OBS networks have been proposed. These schemes make use of deflection routing [4,16], fiber delay line buffering [5,10], wavelength conversion [6,22], and burst segmentation [15,16].…”