ENERGY EFFICIENT ALL-OPTICAL SOA SWITCH FOR THE

“GREEN INTERNET”

Yuri Audzevich, Michele Corrà, Giorgio Fontana, Yoram Ofek, Danilo Severina

Università degli Studi di Trento, Dipartimento di Ingegneria e Scienza dell’Informazione,

via Sommarive 14, POVO, 38100 Trento ITALIA

Introduction

• The possible commercial success of traditional “all-optical switching” depends on the solution of several difficult challenges: like building – optical buffers, – optical header processors, and – optical systems in general.

• When all these problems will be solved, hundreds of Gb/s link speeds will become standard. Unfortunately this is something that might not happen very soon within the current network asynchronous IP switching paradigm.

• An alternative switching paradigm has been recently developed that predetermines the routing configuration of network switches according to SCHEDULED traffic using “freely available” global time or UTC (coordinated universal time) from a variety of sources on earth and in space[1]. Better than 1us accuracy.

• The novel paradigm, called Time Driven Switching (TDS) or Fractional Lambda Switching (FLS), allows the efficient use of all-optical switches RIGHT NOW because it does not require buffers and header processing.

A TDS Network (simplified)

0 10 … 90

0 10 … 90

0 10 … 90

1C

4C

3C

2C

5C 6C

7C

8C 9C

Like Circuit Switching (physical-zero latency),

But you only need to OWN the fraction of the circuit where the datagram is TEMPORARILY located. Precise synchronization is required.

Shown to work, see literature.

Specific hardware:

1) Time Driven servers2) Time Driven switches

Network:

1) TCP/IP can be adopted2) Gb Eth optical can

be adopted

• Pipelines are deployed to increase efficiency:• Optimal method - independent of a specific realization

• Factory (automotive) / computers (CPU)

• Internet Pipeline thanks: GPS/Galileo/multitude of other sources

• Time frames as virtual containers for IP packets– Thus, no header processing

– Tf accuracy of 1µs is sufficient

Pipeline Forwarding with UTC Factor of 20 Lower Cost / Premium Services

1 2 1000

TimeCycle0

1 2 1000

TimeCycle1

1 2 1000

TimeCycle 79

UTC secondwith 80k Time-frames

Time-of-Day or UTC 0beginning of a UTC second

1beginning of a UTC second

fTfTfTfT fT

Current Networking Test-bed Setuphttp://dit.unitn.it/ip-flow/

TDS switch TDS switch

Streaming Media Source Pipeline

Forwarding

router

25 km Optical Fiber

GPS/GALILEO

Streaming Media

UTC1PPS

UTC1PPS

O-EE-O

O-E: Optical-to-Electrical (analog)

E-O: Electrical-to-Optical (analog)

ArbitraryDistance Arbitrary

Distance

Streaming Media

E-OO-E

25 km Optical

Fiber

TDSAll-opticalSwitch

FPGAGPS

FPGAGPSFPGAGPS

UTC1PPS

UTC1PPS

SOA

SOA

SOA

SOA

OUTPUT 1 - 0 dBm

OUTPUT 2 – 0 dBm

MONITOR PD3

MONITOR PD1

FPGA

+

UBLOX-T GPS

POWER AMPForSOA Switchactuation

GPS

LABviewenvironment

IndividualGain control

internet

INPUT 1

INPUT 2

PC

MONITOR PD4

MONITOR PD2

90

90

90

90

10

10

10

10

50/50 50/50

50/50

FC-APC

FC

FC-APC

FC-APC FC-APC

FC-APC FC-APC

FC-APC FC-APC X 8

FC-APC

FC-APC

FC

FC

50/50

Typ. Out of 40km transceiver = -4 to +1 dbm - SOA out +3dbm

All Optical Switch Design

Components

QPhotonics SOA1550

ComBlock COM1300 PCMCIA FPGA

Ublox LEA-4T GPS Timing Receiver

Xilinx Spartan-3 XC3S400-4 FPGA features 400K system gates including 288Kbit of dual port memory and 16 dedicated 18x18 multipliers.

• 32MB SDRAM for use as elastic buffer

Components

Complete Optical Switch

SOA Controller

GPS Timing Panel

Operating Parameters Panel

Switch Scheduling Panel

Eye Pattern

Eye pattern of GbEth transmitter->25km fiber->SOA (25%Inom)->25kmfiber->RX

Inom = 200 mA

Eye Pattern

Eye pattern of GbEth transmitter->25km fiber->SOA (35%Inom)->25kmfiber->RX

Eye Pattern

Eye pattern of GbEth transmitter->25km fiber->SOA (50%Inom)->25kmfiber->RX

Energy Efficiency

• In our 2x2 switch each output fiber requires an average of 1.2 V*100 mA= 120mW of power for SOA power supply. The requirement can be scaled up for larger switches operating within fractional lambda switching and TDS principles.

• 128x128 Banyan switch will require 4x7x64/128=14 SOA per output fiber. To avoid switch blocking the number of SOA simultaneously active per output fiber has to be 7.

• At 10 Gb/s this is 7*120/10 mW/Gb/s = 84 mW/Gb/s that clearly is only 8.4 mW/Gb/s if the switch is operated at 100Gb/s.

• By comparison high-end traditional switches require abut 20 W/Gb/s per output fiber.

• – We have three orders of magnitude lower power!

Conclusion & The Future

• We described a high performance all-optical switch implementing the fractional lambda switching paradigm with time driven scheduled switching. The switch has been successfully tested with BERT at 1.25 Gb/s and with UDP multimedia streams with Gb Ethernet interfaces.

• The switch can scale to very high capacity and provide an energy efficient switching solution for the future green internet. This first combination of TDS with SOA switching is the first small step; much more efforts and funding should be directed towards this new technology for a better characterization of existing hardware and future experimentation on a larger scale, including the important combination of WDM-TDS.

INTERNET KeyWORDS: IPFLOW TRENTO