Optical Signal Processing in All-Optical Packet Routing ... - CiteSeerX
Optical Signal Processing in All-Optical Packet Routing Systems S. J. Ben Yoo Department of Electrical and Computer Engineering, University of California, Davis, California 95616, U. S. A. [email protected], Abstract: This paper discusses important signal processing functions in all-optical packet routing systems. We will pay special attention to all-optical time-to-live, optical performance monitoring, optical label swapping, and optical regeneration. The new optical packet switching router is capable of all-optically achieving necessary routing functions including signal processing typically handled by optoelectronics.
Introduction Modern networks require high-capacity and agile reconfigurability to effectively cope with exponentially growing data traffic in support of diverse new services including multimedia. Optical packet switching routers allow integration of data and optical networking towards the photonic Internet of the future. However, routers must provide ‘time-to-live’ function to avoid looping, performance monitoring to interface with the control & management plane, label-swapping to provide network scalability, and regeneration to support the necessary signal-to-noise ratio. Optical-Label switching (OLS) facilitates introduction of optical packet switching by providing a shim layer between IP and WDM, and allows seamless upgrades from optical circuit switching and burst switching networks. In addition, the optical-label provides a valuable means to support performance monitoring without optical-to-electrical conversion processes in the data plane. This paper discusses successful systems integration of OLS routers, OLS network demonstrations, and future applications with optical signal processing.
The key underlying networking concept behind Optical-Label Switching [1] is an efficient and transparent packet forwarding method using an optical-label switching mechanism which can coexist with legacy WDM technologies on the same fiber. Fig. 1 depicts the underlying concept for a fast connection setup. New signaling information is added in the form of an optical signaling label which is carried in-band within each wavelength in the multi-wavelength transport environment. The optical-label containing routing and control information such as the source, the destination, the priority, and the length of the packet, will propagate through the network along with the data payload. Each optical-label switching router will sense this optical-label, look-up the forwarding table, and take necessary steps to forward the packet. If the packet is to be routed to a wavelength/path where there is already another packet being routed, the optical label switching router (OLSR) will seek routing by an alternate wavelength, by buffering, or by an alternate path. This wavelength, time, and space domain contention resolution is a key to implementing optical-router without heavily relying on time-buffers as conventional electronic routers do [2, 3].
Architecture and Protocol
IPNE
OLS Core Network Core Router
Client Network
Fig. 2. An integrated optical-label switching router system.
LABE L DATA
Systems Integration
Optic al Powe r DATA
Optical Label Switching Core Router LABE L
Optic
Optical Label Switching Edge Router: IPNE al. Fr eq
.
Fig. 1 Fast connection setup using the optical signaling label for the accompanying data payload. Optical Label Switching Routers (OLSR) with Label-Processing interfaces quickly read the label and forward the packet. If there is switching contention on the preferred path, the OLSR will attempt to route using an alternate wavelength, to delay the transport, or to route on an alternate path.
We have successfully integrated optical-label switching routers with wavelength-time-space domain contention resolution capabilities. Fig. 2 illustrates the schematic of the integrated OLSR. The OLSR consists of the optical router controller, the optical label extractor, the optical label rewriter [4,5], the optical label detector, a switch fabric, and client interfaces. The optical router controller, implemented by a field programmable gate array (FPGA) includes the forwarding table, the scoreboard, and the
arbitrator incorporating the wavelength-time-space domain contention resolution algorithm. The opticallabel switching transmitters and receivers employ subcarrier multiplexing for the label and the data payload, and all-optical label extraction is achieved by fiber-Bragg grating and optical-circulators [4]. The switching fabric consists of rapidly tunable wavelength converters and arrayed wavelength grating routers (AWGR) [6] and fixed wavelength converters. The client interfaces are essentially edge routers capable of generating and extracting optical-labels interfacing with legacy client machines like IP routers or ATM switches. Network control and management system and GMPLS extension development are also in progress. With the GMPLS extension, the OLS system is designed to interoperate with MPLS, MPLambdaS and IP [7].
resolution in time, space, wavelength domains have been successfully demonstrated. Recent experiments have also shown a successful field trial across 477 km San Francisco bay dark fiber NTON-Sprint networks, and a demonstration of IP-client-to-IP-client packet switching across an all optical label switching network using the OLS edge routers.
Results
The author is indebted to K. Okamoto and S. Kamei for AWGRs and the UC Davis Optical Switching and Communications Systems Lab for technical contributions. This work was partially funded by DARPA and AFRL under agreement number F30602-00-2-0543, by NSF under grant number ANI-998665, and by the support of OIDA JOP program suppoerted by DARPA and NSF.
The OLSR can utilize the strong correlation between the label and the payload to indirectly estimate the errors in the payload by conducting an error-checking on the labels. Fig. 3. shows the measured BER correlation between the label and the data payload BERs. This strong correlation was used to implement the all-optical TTL.
Conclusion OLS seeks seamless integration between data and optical networking. Successful demonstration of cascaded stages of OLS routing experiments, all-optical variable size packet contention experiments, and 477 km field trials with excellent BER performance imply its viability for future photonic Internet applications.
Acknowledgments
References 1.
Fig. 3 Correlation between payload and label BER 1E-4
3-hop
4- hop
Baseband BB
1E-6 BER
Baseband BB 2-hop 3-hop 4-hop 6-hop 11-hop
6- hop 2-hop 1E-8
11-hop 100ps/div
1E-10 1E-12 -34
100ps/div -30
-26 -22 -18 Average Received Power (dBm)
-14
Fig.4 Successful demonstration of multihop (up to 11 hop) cascaded alloptical packet forwarding.
Refs [3, 8, 9, 10, 11] discuss successful demonstration of the integrated OLSR. Fig. 4. shows the packet BER measurements of cascaded packet forwarding. Very effective 2R regeneration allows cascaded all-optical operations up to 11 hops. 3 R regeneration is expected to extend this reach. Packet-by-packet contention
S. J. B. Yoo and G. K. Chang, “High-Throughput, LowLatency Next Generation Internet Networks using OpticalTag Switching,” U.S. Patent 6,111,673 (1997); and also in S. J. B. Yoo, G. K. Chang, ‘Ultra-low Latency WDM Tag Switching Demonstration for Next Generation Internet Networks’, DARPA proposal in response to NGI initiative, BAA 98-02 (1997). 2. Shun Yao, et al, Technical Digest, OFC 2001, paper TuK2 (2001). 3. S. J. B. Yoo, et al, Technical Digest, OFC2002, paper #WO2,( 2002). 4. Hyuek Jae Lee, et al,IEEE Photon. Techno. Lett., vol 13, p. 635-637, (2001). 5. D. J. Blumenthal, Technical Digest, OFC2002, paper #WO3, (2002). 6. K. Okamoto, et al, IEE Electron. Lett., vol. 33, pp. 18651866, (1997). 7. S. J. B. Yoo, Technical Digest, SPIE Asia-Pacific Optical and Wireless Communications, Paper 4585-02 (2001) 8. V.J. Hernandez, et al, Technical Digest OFC2002, paper #TuY4, (2002). 9. S. J. B. Yoo, et al, IEEE Photon. Techno. Lett., vol 14, no. 8, (2002). 10. Z. Pan, H. Yang, Z. Zhu, Ji. Cao, V. Akella, S. Butt, S. J. B. Yoo, “Demonstration of Variable-Size Packet Contention Resolution and Packet Forwarding in an Optical-Label Switching Router,” IEEE Photonics Technology Letters, vol. 16, no. 4, July 2004. (2004). 11. S.J.B. Yoo, F. Xue, Y. Bansal, J. Taylor, Z. Pan, J. Cao, M. Jeon, T. Nady, G. Goncher, K.Boyer, K.i Okamoto, S. Kamei, and Venkatesh Akella, "High-Performance OpticalLabel Switching Packet Routers and Smart Edge Routers for the Next Generation Internet," Selected Areas in Communications, IEEE Journal on , Volume: 21, Issue: 7, pp. 1041-1051, Sept. 2003. (2003)
Introduction Modern networks require high-capacity and agile reconfigurability to effectively cope with exponentially growing data traffic in support of diverse new services including multimedia. Optical packet switching routers allow integration of data and optical networking towards the photonic Internet of the future. However, routers must provide ‘time-to-live’ function to avoid looping, performance monitoring to interface with the control & management plane, label-swapping to provide network scalability, and regeneration to support the necessary signal-to-noise ratio. Optical-Label switching (OLS) facilitates introduction of optical packet switching by providing a shim layer between IP and WDM, and allows seamless upgrades from optical circuit switching and burst switching networks. In addition, the optical-label provides a valuable means to support performance monitoring without optical-to-electrical conversion processes in the data plane. This paper discusses successful systems integration of OLS routers, OLS network demonstrations, and future applications with optical signal processing.
The key underlying networking concept behind Optical-Label Switching [1] is an efficient and transparent packet forwarding method using an optical-label switching mechanism which can coexist with legacy WDM technologies on the same fiber. Fig. 1 depicts the underlying concept for a fast connection setup. New signaling information is added in the form of an optical signaling label which is carried in-band within each wavelength in the multi-wavelength transport environment. The optical-label containing routing and control information such as the source, the destination, the priority, and the length of the packet, will propagate through the network along with the data payload. Each optical-label switching router will sense this optical-label, look-up the forwarding table, and take necessary steps to forward the packet. If the packet is to be routed to a wavelength/path where there is already another packet being routed, the optical label switching router (OLSR) will seek routing by an alternate wavelength, by buffering, or by an alternate path. This wavelength, time, and space domain contention resolution is a key to implementing optical-router without heavily relying on time-buffers as conventional electronic routers do [2, 3].
Architecture and Protocol
IPNE
OLS Core Network Core Router
Client Network
Fig. 2. An integrated optical-label switching router system.
LABE L DATA
Systems Integration
Optic al Powe r DATA
Optical Label Switching Core Router LABE L
Optic
Optical Label Switching Edge Router: IPNE al. Fr eq
.
Fig. 1 Fast connection setup using the optical signaling label for the accompanying data payload. Optical Label Switching Routers (OLSR) with Label-Processing interfaces quickly read the label and forward the packet. If there is switching contention on the preferred path, the OLSR will attempt to route using an alternate wavelength, to delay the transport, or to route on an alternate path.
We have successfully integrated optical-label switching routers with wavelength-time-space domain contention resolution capabilities. Fig. 2 illustrates the schematic of the integrated OLSR. The OLSR consists of the optical router controller, the optical label extractor, the optical label rewriter [4,5], the optical label detector, a switch fabric, and client interfaces. The optical router controller, implemented by a field programmable gate array (FPGA) includes the forwarding table, the scoreboard, and the
arbitrator incorporating the wavelength-time-space domain contention resolution algorithm. The opticallabel switching transmitters and receivers employ subcarrier multiplexing for the label and the data payload, and all-optical label extraction is achieved by fiber-Bragg grating and optical-circulators [4]. The switching fabric consists of rapidly tunable wavelength converters and arrayed wavelength grating routers (AWGR) [6] and fixed wavelength converters. The client interfaces are essentially edge routers capable of generating and extracting optical-labels interfacing with legacy client machines like IP routers or ATM switches. Network control and management system and GMPLS extension development are also in progress. With the GMPLS extension, the OLS system is designed to interoperate with MPLS, MPLambdaS and IP [7].
resolution in time, space, wavelength domains have been successfully demonstrated. Recent experiments have also shown a successful field trial across 477 km San Francisco bay dark fiber NTON-Sprint networks, and a demonstration of IP-client-to-IP-client packet switching across an all optical label switching network using the OLS edge routers.
Results
The author is indebted to K. Okamoto and S. Kamei for AWGRs and the UC Davis Optical Switching and Communications Systems Lab for technical contributions. This work was partially funded by DARPA and AFRL under agreement number F30602-00-2-0543, by NSF under grant number ANI-998665, and by the support of OIDA JOP program suppoerted by DARPA and NSF.
The OLSR can utilize the strong correlation between the label and the payload to indirectly estimate the errors in the payload by conducting an error-checking on the labels. Fig. 3. shows the measured BER correlation between the label and the data payload BERs. This strong correlation was used to implement the all-optical TTL.
Conclusion OLS seeks seamless integration between data and optical networking. Successful demonstration of cascaded stages of OLS routing experiments, all-optical variable size packet contention experiments, and 477 km field trials with excellent BER performance imply its viability for future photonic Internet applications.
Acknowledgments
References 1.
Fig. 3 Correlation between payload and label BER 1E-4
3-hop
4- hop
Baseband BB
1E-6 BER
Baseband BB 2-hop 3-hop 4-hop 6-hop 11-hop
6- hop 2-hop 1E-8
11-hop 100ps/div
1E-10 1E-12 -34
100ps/div -30
-26 -22 -18 Average Received Power (dBm)
-14
Fig.4 Successful demonstration of multihop (up to 11 hop) cascaded alloptical packet forwarding.
Refs [3, 8, 9, 10, 11] discuss successful demonstration of the integrated OLSR. Fig. 4. shows the packet BER measurements of cascaded packet forwarding. Very effective 2R regeneration allows cascaded all-optical operations up to 11 hops. 3 R regeneration is expected to extend this reach. Packet-by-packet contention
S. J. B. Yoo and G. K. Chang, “High-Throughput, LowLatency Next Generation Internet Networks using OpticalTag Switching,” U.S. Patent 6,111,673 (1997); and also in S. J. B. Yoo, G. K. Chang, ‘Ultra-low Latency WDM Tag Switching Demonstration for Next Generation Internet Networks’, DARPA proposal in response to NGI initiative, BAA 98-02 (1997). 2. Shun Yao, et al, Technical Digest, OFC 2001, paper TuK2 (2001). 3. S. J. B. Yoo, et al, Technical Digest, OFC2002, paper #WO2,( 2002). 4. Hyuek Jae Lee, et al,IEEE Photon. Techno. Lett., vol 13, p. 635-637, (2001). 5. D. J. Blumenthal, Technical Digest, OFC2002, paper #WO3, (2002). 6. K. Okamoto, et al, IEE Electron. Lett., vol. 33, pp. 18651866, (1997). 7. S. J. B. Yoo, Technical Digest, SPIE Asia-Pacific Optical and Wireless Communications, Paper 4585-02 (2001) 8. V.J. Hernandez, et al, Technical Digest OFC2002, paper #TuY4, (2002). 9. S. J. B. Yoo, et al, IEEE Photon. Techno. Lett., vol 14, no. 8, (2002). 10. Z. Pan, H. Yang, Z. Zhu, Ji. Cao, V. Akella, S. Butt, S. J. B. Yoo, “Demonstration of Variable-Size Packet Contention Resolution and Packet Forwarding in an Optical-Label Switching Router,” IEEE Photonics Technology Letters, vol. 16, no. 4, July 2004. (2004). 11. S.J.B. Yoo, F. Xue, Y. Bansal, J. Taylor, Z. Pan, J. Cao, M. Jeon, T. Nady, G. Goncher, K.Boyer, K.i Okamoto, S. Kamei, and Venkatesh Akella, "High-Performance OpticalLabel Switching Packet Routers and Smart Edge Routers for the Next Generation Internet," Selected Areas in Communications, IEEE Journal on , Volume: 21, Issue: 7, pp. 1041-1051, Sept. 2003. (2003)
