The rapid growth of data communications and the deployment of optical communication systems that utilize wavelength division multiplexing (WDM) created a demand for new switching methods. Optical packet switching is considered today a switching method that is particularly suitable for data communications based on the Internet Protocol (IP) and for optical communication systems that utilize WDM.
There are two main techniques for implementing optical packet switching. The two techniques mainly differ in structure of optical packets used thereby, and in switching node operation modes that result from the different structures of the optical packets. The first technique employs fixed-length packets and a synchronous mode of operation of switching nodes, and the second technique employs variable-length packets and an asynchronous mode of operation of switching nodes. Asynchronous variable-length packets are also referred to as bursts and the second technique is therefore also referred to as optical burst switching (OBS).
Basic aspects of the foregoing techniques of optical packet switching are described in the following publications:
an article entitled “Architectural and Technological Issues for Future Optical Internet Networks”, by Listanti et al in IEEE Communications Magazine, September 2000, pages 82–92;
an article entitled “IP Over Optical Networks: Architectural Aspects”, by Rajagopalan et al in IEEE Communications Magazine, September 2000, pages 94–102;
an article entitled “Labeled Optical Burst Switching for IP-over-WDM Integration”, by Chunming Qiao in IEEE Communications Magazine, September 2000, pages 104–114; and
an article entitled “Approaches to Optical Internet Packet Switching”, by Hunter et al in IEEE Communications Magazine, September 2000, pages 116–122.
Both techniques of optical packet switching mentioned above require careful traffic engineering in order to enable efficient transmission of optical packets and efficient utilization of wavelength resources.
State-of-the-art traffic engineering techniques attempt to optimize allocation of wavelengths to incoming optical packets in order to utilize each wavelength that carries optical packets with as little as possible gaps between adjacent optical packets, and to reduce congestion and loss of packets. Therefore, sophisticated wavelength selection and packet scheduling algorithms have been proposed for determining, for each incoming optical packet, a carrier wavelength from among N wavelengths that is most suitable in terms of availability and gap filling, where N is an integer greater than one. Such traffic engineering techniques are described in the following publications:
an article entitled “A framework for unified traffic engineering in IP over WDM networks”, by Song et al in Optical Networks Magazine, November/December 2001, pages 28–33; and
an article entitled “Optimization of wavelength allocation in WDM optical buffers”, by Callegati et al in Optical Networks Magazine, November/December 2001, pages 66–72.
However, as optical switches become more complex with more wavelengths used thereby, N increases thereby increasing computation complexity of prior art traffic engineering algorithms which results in a demand for more powerful and more expensive computation resources. Additionally, since the prior art algorithms do not distinguish among optical packets having different attributes of packet characteristics, undesired events may occur, such as events in which delay insensitive optical packets are switched before delay sensitive optical packets thereby delaying transmission of the delay sensitive optical packets. Therefore, techniques that can reduce computation complexity and prevent problems encountered with switching of optical packets having different attributes of packet characteristics may be highly desired.
Some aspects of technologies and related art that may be useful in understanding the present invention are described in the following publications:
an article entitled “Mining the Optical Bandwidth for a Terabit per Second”, by Alan Eli Willner in IEEE Spectrum, April 1997, pages 32–41;
an article entitled “Polarization Insensitive Widely Tunable All-Optical Clock Recovery Based on AM Mode-Locking of a Fiber Ring Laser”, by Wang et al in IEEE Photonics Technology Letters, Vol. 12, No. 2, February 2000, pages 211–213;
an article entitled “Ultra-High-Speed PLL-Type Clock Recovery Circuit Based on All-Optical Gain Modulation in Traveling-Wave Laser Diode Amplifier”, by Kawanishi et al in Journal of Lightwave Technology, Vol. 11, No. 12, December 1993, pages 2123–2129;
an article entitled “Prescaled 6.3 GHz clock recovery from 50 GBit/s TDM optical signal with 50 GHz PLL using four-wave mixing in a traveling-wave laser diode optical amplifier”, by Kamatani et al in Electronics Letters, Vol. 30, No. 10, May 12, 1994, pages 807–809;
an article entitled “Variable optical delay line with diffraction-limited autoalignment” by Klovekorn et al in Applied Optics, Vol. 37, No. 10, Apr. 1, 1998, pages 1903–1904;
an article entitled “Picosecond-Accuracy All-Optical Bit Phase Sensing Using a Nonlinear Optical Loop Mirror”, by Hall et al in IEEE Photonics Technology Letters, Vol. 7, No. 8, August 1995, pages 935–937;
an article entitled “An Ultrafast Variable Optical Delay Technique”, by Hall et al in IEEE Photonics Technology Letters, Vol. 12, No. 2, February 2000, pages 208–210;
an article entitled “Optical switching promises cure for telecommunications logjam”, by Jeff Hecht in Laser Focus World, September 1998, pages 69–72;
an article entitled “Design and Cost Performance of the Multistage WDM-PON Access Networks”, by Maier et al in Journal of Lightwave Technology, Vol. 18, No. 2, February 2000, pages 125–143;
an article entitled “All-optical networks need optical switches”, by Jeff Hecht in Laser Focus World, May 2000, pages 189–196;
a technology brief entitled “Lucent Upgrades Wavestar to 320-Channel, 800-Gb/s Transmission”, in Photonics Spectra, June 2000, page 46;
an article entitled “Record Data Transmission Rate Reported at ECOC 96”, by Paul Mortensen in Laser Focus World, November 1996, pages 40–42;
an article entitled “Multiple Wavelengths Exploit Fiber Capacity”, by Eric J. Lerner in Laser Focus World, July 1997, pages 119–125;
an article entitled “Advances in Dense WDM Push Diode-Laser Design”, by Diana Zankowsky in Laser Focus World, August 1997, pages 167–172;
an article entitled “Multistage Amplifier Provides Gain Across 80 nm”, by Kristin Lewotesky in Laser Focus World, September 1997, pages 22–24;
an article entitled “WDM Local Area Networks”, by Kazovsky et al in IEEE LTS, May 1992, pages 8–15;
an article entitled “Optical Switches Ease Bandwidth Crunch”, by Rien Flipse in EuroPhotonics, August/September 1998, pages 44–45;
an article entitled “Speed Demons: Is ‘Faster’ Better and Cheaper?”, by Stephanie A. Weiss in Photonics Spectra, February 1999, pages 96–102;
an article entitled “Wavelength Lockers Keeps Laser in Line”, by Ed Miskovic in Photonics Spectra, February 1999, pages 104–110;
an article entitled “Optical switches pursue crossconnect markets”, by Hassaun Jones-Bay in Laser Focus World, May 1998, pages 153–162;
a conference review entitled “Optical amplifiers revolutionize communications”, by Gary T. Forrest in Laser Focus World, September 1998, pages 28–32;
an article entitled “Combining gratings and filters reduces WDM channel spacing”, by Pan et al in Optoelectronics World, September 1998, pages S11–S17;
an article entitled “Demand triggers advances in dense WDM components”, by Raymond Nering in Optoelectronics World, September 1998, pages S5–S8;
an article entitled “Optical Networks Seek Reconfigurable Add/Drop Options”, by Hector E. Escobar in Photonics Spectra, December 1998, pages 163–167;
an article entitled “Ultrafast Optical Switch Unveiled”, by Michael D. Wheeler in Photonics Spectra, December 1998, page 42,
an article entitled “Data express Gigabit junction with the next-generation Internet”, by Collins et al in IEEE Spectrum, February 1999, pages 18–25;
an article entitled “Designing Broadband Fiber Optic Communication Systems”, by Juan F. Lam in Communication Systems Design magazine, February 1999, pages 1–4 at http://www.csdmag.com;
an article entitled “Terabit/second-transmission demonstrations make a splash at OFC '96”, in Laser Focus World, April 1996, page 13;
an article entitled “Multigigabit Networks: The Challenge”, by Rolland et al in IEEE LTS, May 1992, pages 16–26;
an article entitled “Direct Detection Lightwave Systems: Why Pay More?”, by Green et al in IEEE LCS, November 1990, pages 36–49;
an article entitled “Photonics in Switching”, by H. Scott Hinton in IEEE LTS, August 1992, pages 26–35;
an article entitled “Advanced Technology for Fiber Optic Subscriber Systems”, by Toba et al in IEEE LTS, November 1992, pages 12–18;
an article entitled “Fiber amplifiers expand network capacities”, by Eric J. Lerner in Laser Focus World, August 1997, pages 85–96;
an article entitled “Technologies for Local-Access Fibering”, by Yukou Mochida in IEEE Communications Magazine, February 1994, pages 64–73;
an article entitled “Wavelength Assignment in Multihop Lightwave Networks”, by Ganz et al in IEEE Transactions on Communications, Vol. 42, No. 7, July 1994, pages 2460–2469;
an article entitled “Wavelength-Division Switching Technology in Photonic Switching Systems”, by Suzuki et al in IEEE International Conference on Communications ICC '90, pages 1125–1129;
an article entitled “Branch-Exchange Sequences for Reconfiguration of Lightwave Networks”, by Labourdette et al in IEEE Transactions on Communications, Vol. 42, No. 10, October 1994, pages 2822–2832;
an article entitled “Use of Delegated Tuning and Forwarding in Wavelength Division Multiple Access Networks”, by Auerbach et al in IEEE Transactions on Communications, Vol. 43, No. 1, January 1995, pages 52–63;
an article entitled “Compact 40 Gbit/s optical demultiplexer using a GaInAsP optical amplifier”, by Ellis et al in Electronics Letters, Vol. 29, No. 24, Nov. 25, 1993, pages 2115–2116;
an article entitled “Bit-Rate Flexible All-Optical Demultiplexing Using a Nonlinear Optical Loop Mirror”, by Patrick et al in Electronics Letters, Vol. 29, No. 8, Apr. 15, 1993, pages 702–703;
an article entitled “All-Optical High Speed Demultiplexing with a Semiconductor Laser Amplifier in a loop Mirror Configuration”, by Eiselt et al in Electronics Letters, Vol. 29, No. 13, Jun. 24, 1993, pages 1167–1168;
an article entitled “Photonic Switches: Fast, but Functional?”, by Daniel C. McCarthy in Photonics Spectra, March 2001, pages 140–150;
an article entitled “Photonic packet switching and optical label swapping”, by Daniel J. Blumenthal in Optical Networks Magazine, November/December 2001, pages 54–65;
an article entitled “A Simple Dynamic Integrated Provisioning/Protection Scheme in IP Over WDM Networks”, by Ye et al in IEEE Communications Magazine, November 2001, pages 174–182;
an article entitled “XOR: A Logical Choice for All-Optical Networks”, by Perry J. Greenbaum in Photonics Spectra, November 2001, pages 30–31;
U.S. Pat. No. 5,170,273 to Nishio which describes a cross-talk reducing optical switching system which receives electrical digital signals at its input terminal;
U.S. Pat. No. 5,191,457 to Yamazaki that describes a WDM optical communication network in which optical beams are modulated by channel discrimination signals of different frequencies;
U.S. Pat. No. 5,194,977 to Nishio that describes a wavelength division switching system with reduced optical components using optical switches;
U.S. Pat. No. 5,557,439 to Alexander et al. that describes wavelength division multiplexed optical communication systems configured for expansion with additional optical signal channels;
U.S. Pat. No. 5,680,490 to Cohen et al. that describes a comb splitting system which demultiplexes and/or multiplexes a plurality of optical signal channels at various wavelengths;
U.S. Pat. No. 5,712,932 to Alexander et al. that describes reconfigurable wavelength division multiplexed systems which include configurable optical routing systems;
U.S. Pat. Nos. 5,724,167 and 5,739,935 to Sabella that describe an optical cross-connect node architecture that interfaces plural optical fiber input and output links, each link containing plural wavelength channels;
U.S. Pat. No. 5,457,687 to Newman that describes reactive congestion control in an ATM network where the network is formed by the interconnection of nodes each including a forward path for transfer of information from source to destination through the network and a return path for returning congestion control signals;
U.S. Pat. No. 5,774,244 to Tandon et al. that describes an optical communications network that includes a plurality of passive optical networks (PONs) connected in a ring in PON address order, in which communication channels between terminals are wavelength multiplexed;
U.S. Pat. No. 6,233,082 to Johnson that describes an optical transmitter for generating any one of N carrier signals for use in an M-channel WDM system;
U.S. Pat. No. 5,867,289 to Gerstel et al that describes a fault detecting apparatus and method for a network node of an optical transmission system that receives a wavelength division multiplexed (WDM) optical signal which includes a group of optical channels;
U.S. Pat. No. 6,108,112 to Touma that describes non-faulty subscriber equipment that is quickly recovered from a communication failure caused by faulty subscriber equipment;
U.S. Pat. No. 4,626,075 to Chemla that describes a nonlinear optical device that includes a layered semiconductor structure having layers of different energy band gap materials;
U.S. Pat. No. 5,452,115 to Tomioka that describes a communication system that includes a wavelength multiplexing network having a plurality of transmission channels of different wavelengths, a plurality of nodes interconnected by the wavelength multiplexing network for performing data communications with other nodes using time slots into which time on each of the transmission channels is divided, each of the nodes having its transmitting wavelength fixed and unique to a node and its receiving wavelength set tunable, and a network controller for centrally controlling time slot allocation repeated for each frame to the nodes; and
The following chapters in The Communications Handbook, CRC Press & IEEE Press, 1997, Editor-in-Chief Jerry D. Gibson: Chapter 37 on pages 513–528; Chapter 39 on pages 542–553; Chapter 40 on pages 554–564; Chapter 46 on pages 622–649; Chapter 51 on pages 686–700; and Chapter 65 on pages 883–890.
U.S. patent application Ser. No. 09/126,378 of Handelman, now U.S. Pat. No. 6,404,522, describes improvements in communication performance of an optical communication system that communicates data via N different channel wavelengths using WDM.
U.S. patent application Ser. No. 09/389,345 of Handelman, now U.S. Pat. No. 6,574,018, describes a network control system that may be embodied in various elements of a communication network that communicates optical signals multiplexed by WDM. The network control system may limit a number of channel wavelengths actually used for communicating optical signals to an end node, and control and modify data rates carried over channel wavelengths multiplexed by WDM.
U.S. patent application Ser. No. 09/624,983 of Handelman, now U.S. Pat. No. 6,763,191, describes an optical switching apparatus that selectively combines and separates series of optical signal samples using OTDM and/or WDM.
U.S. patent application Ser. No. 09/976,243 of Handelman et al, now published as Pub. No. US 2002/0048067, describes an optical switching apparatus that selectively combines and separates, using OTDM and/or WDM, optical signal samples that are obtained by a spread spectrum technique or a combination of optical signal samples that are obtained by a spread spectrum technique and optical signal samples that are carried over discrete channel wavelengths.
The disclosures of all references mentioned above and throughout the present specification are hereby incorporated herein by reference.