Optical Packet Buffers for Backbone Internet Routers

Seamless Interconnection for Universal Services. Global Telecommunications Conference. GLOBECOM'99. (Cat. No.99CH37042), 1999

We describe optical buffers with non-uniform distribution of the delay lines, so-called nondegenerate buffers. Coupled with an intelligent scheduling algorithm, nondegenerate buffers feature improved system performance leading to more efficient and larger optical buffers for optical IP routers. We demonstrate that the concept under bursty, both time-slotted and asynchronous traffic conditions, can lead to a sizable reduction in buffer depth requirements compared to conventional solutions. The simulations point to the fact that in optical IP routers operating under asynchronous conditions, this would almost be a mandatory solution.

Optics Express, 2009

A chip-scale optical buffer performs autonomous contention resolution for 40-byte packets with 99% packet recovery. The buffer consists of a fast, InP-based 2x2 optical switch and a silica-on-silicon low loss delay loop. The buffer is demonstrated in recirculating operation, but may be reconfigured in feed-forward operation for longer packet lengths. The recirculating buffer provides packet storage in integer multiples of the delay length of 12.86 ns up to 64.3 ns with 98% packet recovery. The buffer is used to resolve contention between two 40 Gb/s packet streams using multiple photonic chip optical buffers.

Journal of Lightwave Technology, 2001

We present a new wavelength-routed photonic packet buffer that combines traveling delay lines with delay-line loops. The new packet buffer can effectively capitalize on the simplicity of traveling delay lines and the flexibility of delay-line loops. Three different packet buffering and scheduling techniques are investigated. The effectiveness of the new packet buffer is evaluated by computer simulation using a random traffic model. The simulation results show that the new packet buffer, in conjunction with the buffering and scheduling techniques, can efficiently make use of buffering spaces and, hence, substantially reduce the packet-loss probability by several orders of magnitude. Index Terms-Packet scheduling, photonic packet switching, wavelength conversion, wavelength routing, wavelength division multiplexing (WDM) packet buffer.

2011 IEEE 12th International Conference on High Performance Switching and Routing, 2011

The rapid increase in Internet traffic is forcing packet routers to grow in capacity to meet the demand. Optical packet routers with less buffering and a greater degree of optical transparency are actively being researched as a way to improve energy efficiency and capacity scaling over traditional electronic routers. Since it is difficult to buffer packets in the optical domain, in this paper we analyze the performance of a hybrid optoelectronic packet router. The router architecture has multiple optical switch planes and a shared electronic buffer to resolve output-port contention. By using multiple ports on the switch planes for each input and output fiber, and by using some switchplane ports to interconnect the planes, we can achieve a relatively low packet loss ratio in a router with no buffer. In this case, most traffic can be switched using only the through optical paths of the router without entering the shared buffer. The shared electronic buffer is primarily used to reduce the packet drop ratio under periods of heavy loads and occasionally for optical regeneration of a packet. We run extensive simulations to evaluate the performance of the router with varying number of switch plane ports, number of connections to the electronic buffer, and number of interconnections between the switch planes. We show that the router can provide good throughput, with realistic on-off bursty traffic and asynchronous packet arrivals.

2006

We describe the design and initial results of an all-optical buffered 40 Gb/s packet switch. Dynamic packet forwarding is illustrated and specific attention is directed to buffering. We assess the challenges in meeting the requirements for optical buffering devices. Slow light and delay line buffering approaches are described and several recent results and issues are summarized.

Journal of Lightwave Technology, 1998

This paper consists of a categorization of optical buffering strategies for optical packet switches, and a comparison of the performance of these strategies both with respect to packet loss/delay and bit error rate (BER) performance. Issues surrounding optical buffer implementation are discussed, and representative architectures are introduced under different categories. Conclusions are drawn about packet loss and BER performance, and about the characteristics an architecture should have to be practical. It is shown that there is a strong case for the use of optical regeneration for successful cascading of these architectures.

Journal of Lightwave Technology, 1998

Photonic packet buffers are essential components in photonic packet switching systems. We present a wavelength routing-based photonic packet buffer based on a state-of-the-art arrayed-waveguide grating (AWG) multiplexer. We show how this new packet buffer can be effectively used in the implementation of photonic packet switching systems. We also propose and examine two different photonic packet switch architectures.

Optical Fiber …, 2006

Packet-switched routers need buffers during times of congestion. We show that a combined input-output queued router needs no more buffering than an output queued router. Using simulations, we show that 10-20 packet buffers are enough.

IEEE Journal on Selected Areas in Communications, 2000

We discuss the introduction/implementation of optical IP routers, then we introduce a novel scheduling algorithm incorporating void filling and aimed at optical routing of asynchronous, variable packet length packets. We describe its structure and discuss the complexity issues. Albeit introduced with the purpose of cancelling the expensive optical synchronization, we argue that this approach represents the most viable all-optical approach for implementing packets-over-SONET (IP-centric scenario). We also present simulations under self-similar traffic conditions which point to the inefficiency of optical buffering to combat the effects of self-similarity, and we outline alternative strategies for proper buffer dimensioning.

Photonic Network Communications, 2013

Optical switching (Optical Packet Switching, Optical Burst Switching, and others) provides alternatives to the current switching in backbone networks. To switch optically, also packet buffering is to be done optically, by means of Fiber Delay Lines (FDLs). Characteristic of the resulting optical buffer is the quantization of possible delays: only delays equal to the length of one of the FDLs can be realized. An important design challenge is the optimization of the delay line lengths for minimal packet loss. To this end, we propose a heuristic based on two existing queueing models: one with quantization and one with impatience. Combined, these models yield an accurate performance modeling heuristic. A key advantage of this heuristic is that it translates the optical buffer problem into two well-known queueing problems, with accurate performance expressions available in the literature. This paper presents the heuristic in detail, together with several figures, comparing the heuristic's output to existing approaches, validating its high accuracy.