Optical burst and packet switching (the long term goal of optical networking !/?) Lars Dittmann,

1. Optical burst and packet switching (the long term goal of optical networking !/?) Lars Dittmann, NET•COM•DTU, Technical University of Denmark ld@com.dtu.dk www.com.dtu.dk

2. Two areas addressed in this talk: • Optical network in general (short and long term) • Optical switching (the E-Photon/ONE perspective) www.com.dtu.dk

3. Optical networking – what is that? • Optical networking and optical transmission is often confused !! • Generic SDH/SONET is often called “first generation optical networks” – but optics is in no respect involved in any networking function i.e. only static point-to-point connection (but first time optical transmission was standardised). • Optical networks contains elements where the optical signal (in the optical domain) can be routed/switched in several directions. - and due to that, is optical network typically analogue networks and as such very simple. www.com.dtu.dk

4. Transport network rather than optical networks • Current evolution of transport network (short term 0-5 years) • Next generation SDH/SONET (VCAT/LCAS – flexible and dynamic bandwidth, circuit switched capacity below a wavelength) • PBT – proprietary Ethernet extension to MAC-in-MAC (driven by NORTEL and BT) – Circuit oriented packet switching • T-MPLS – standardised extension to Ethernet (driven by ALCATEL/LUCENT) – circuit oriented packet switching. • Ethernet based – extended with routing functions and resource reservation. • No transport network – just pure transmission (driven by Cisco and Juniper) www.com.dtu.dk

5. Trends in optical networking • Today the optical network technology is (slowly) evolving (in many domains) and is getting more mature for use in operational network. • WDM enabled the used of wavelength routed network • With or without wavelength conversion (studies indicates that wavelength converters are mainly an advantage when traffic is highly dynamic) • The Internet and migration towards packet mode handling of services pushed for time-domain operation in all layer – including the optical layer. • IP over DWDM – slim layered structure with optics taking over all functionalities below the IP layer (high bandwidth, efficient bandwidth management and QoS, network resilience etc.) www.com.dtu.dk

6. Trends in optical networking • Long terms wavelength assignment • Fast wavelength assignment (wavelength switching) • Burst switching (or very fast wavelength switching) • Packet (or cell) switching (fixed or variable packets) • Overall trend: more time domain dynamics driven by changes in application demands and better optimization and utilization of bandwidth resources) www.com.dtu.dk

7. Key problems in optical networking • Technological problems are many – a number of things proven in lab or in small scale, but hard to move into reliable operational networks. Including the optical flip/flop and 3R that is first step to make optical networking digital) • Administrative problems (in addition of getting access to the signal) is also hugely addressed – specially for wavelength routed networks, but also for OBS and OPS networks. • However – optical networking only make sense in relation to a transport networks as an optical packet router is not a one-to-one replacement for an IP router. www.com.dtu.dk

8. Service/application layers Control Integrated Control/Management Transport network layers Management Trends in network administration (network resources) • Classic split in network control (realtime operation) and network management (off-line). • Network control being automated and based on algorithms and local knowledge • Network management based on manual interaction and global knowledge. • Trend: Stronger integration of control and management – dynamic operation in all layers www.com.dtu.dk

9. MPLS e.g. ASON/ASTN e.g. GMPLS Trends in network administration (network resources) Integrated system vs. segmented systems. Higher layer Service/application oriented (Packet/cell switched) Higher loop Integrated loop Lower layer Physical media oriented (Circuit switched ??) Lower loop www.com.dtu.dk

10. OBS&GMPLS PROPOSAL for OBS and GMPLS integration Integration of GMPLS and OBS function – hybrid control plane Source: Anna Vasileva Manolova COM-DTU, ” Contention Resolution in OBS Networks with GMPLS Control” www.com.dtu.dk

11. Comments • Despite it is said that the optical technology provides unlimited resources – most trends in different areas of optical networking is focusing on resource optimization._____________________________________ • Both OBS and OPS aim at better resource granularity and higher utilization compared to pure WDM networks. • Control systems aim a having a direct related modification of resource assignment in lower layers (potentially having more stable routing table in application layers)_____________________________________ • Why do we care about resource optimization in the optical layer, when cables usually contains tens or hundreds of fibers that with cheap CWDM easily provides a small (and typical) number of wavelength per fiber. (For the access we aim at ulimited bandwidth.) www.com.dtu.dk

12. VD-S: Optical Switching Systems Overview of Research in Optical Switching (VD-S: Virtual Department Switching)

13. Key issues identified by partners as scope of work: • Optical Packet Switching • Optical Buffering • Wavelength Converter Usage Reduction • Optical Signal Monitoring • Packet Compression Techniques • Recovery Switching • Quality of Service in Switches • Physical Impairment Based Switching • Optical Clock Recovery • Wavelength Conversion by Nonlinear Effects • Optical Flip-Flops • Hybrid Optical Switch Architectures • GMPLS Optical Switch Nodes • Contention Resolution Schemes • OTDM Time-slot Switching • Multi-wavelength Regeneration • Optical Cross Connect • 2R Regeneration • OCDM encoders/decoders • Optical Multicast Architecture www.com.dtu.dk

14. Signaling Protocol Extensions forConverter-saving Wavelength Assignment in GMPLS Optical Networks N. Andriolli1, J. Buron2, S. Ruepp2, F. Cugini3, L. Valcarenghi1, P. Castoldi1 1: Scuola Superiore Sant’Anna di Studi Universitari e di Perfezionamento, Pisa, Italy 2: Department of Communications, Optics & Materials, DTU, Copenhagen, Denmark 3: CNIT, National Laboratory of Photonic Networks, Pisa, Italy IEEE Workshop on High Performance Switching and Routing HPSR 2006 – Poznań

15. The wavelength assignment process performed by GMPLS signaling can be optimized • Use standard and novel signaling extensions to collect information on the label preference from the nodes along the path • Design node-local algorithms exploiting these extensions to reach the specific target Minimize wavelength converterutilization in wavelength-routed optical networks Motivations GMPLS framework strong candidate to control next generation data networks • Extends connection-oriented, traffic-engineered MPLS approach to multiple switching layers • Defines specific protocol extensions to simplify operation in WDM optical networks • Converter waste increases: • the network cost • the blocking probability, with a limited amount of WC www.com.dtu.dk

16. PATH message: l1 l3 l1 l3l4 l1 l2 l4 • From source to destination • May carry additional objects, such as the Label Set Label Set = PATH PATH PATH Not designed to avoidunnecessary WC l1 Asource B WC C WC Ddest l2 l3 RESV message: l4 • From destination to source • Carries the wavelength selected by each upstream node for its previous hop RESV RESV RESV RESV RESV RESV l3 l1 l1 l2 l1 l3 LSP setup procedure • Routing: shortest path on the sub-graph with links having at least an available wavelength • Wavelength assignment: signaling session along the found path WavelengthConversion www.com.dtu.dk

17. Suggested Vector l1 l3 l1 l2 l4 l1 l3 l4 Label Set = PATH PATH PATH In this scenario SV contains the number of conversions needed to use the corresponding label l1 Label reservation algorithm Asource B C Ddest l2 SV computing algorithm • At destination, reserve the label with minimum received SV and propagate it as far as possible • If a conversion is needed, reserve the label with minimum received SV l3 l4 • Source node: 0 for any label (no WC) • Intermediate nodes: same value for labels available on the previous hop, otherwise minimum received SV + 1 RESV RESV RESV l1 l1 l1 Label preference with Suggested Vector • Novel optional object included in PATH message • Indicates the preference level for each wavelength within the Label Set • General purpose: allows to rank wavelengths according to a given preference metric 0 1 0 0 0 0 1 0 www.com.dtu.dk

18. Optical flip-flop based on Erbium-Ytterbium doped fibre Mirco Scaffardi, SSSUP, Pisa www.com.dtu.dk

19. Operating principle stimulated emission absorption t Fibre transparent Fibre not transparent Reset pulses t Set pulses Pulsewidth: 10 ns Rep. Frequency: ~ 900 kHz Pulse energy: 19.82 nJ t Read Signal (1541 nm) Reset Pulses (1565 nm) circulator out 1 CW 1541 nm 2 50/50 3 coupler Er3+/Yb fiber t Set Pulses (1535 nm) t 1,5 m t Pulsewidth: 10 ns Rep. Frequency: ~ 900 kHz Pulse energy: 18.48 nJ =1541 nm out www.com.dtu.dk

20. Experimental results Pread=-12dBm PSet =9dBm Set pulses Reset pulses 422 ns 1102 ns Input (a.u.) Output (a.u.) 1.25 mV 1102 ns 680 ns Time (µs) Time (µs) Pread=-4dBm PSet =12dBm • Transition time of 10 ns measured. • Transition time reduced increasing set and reset power and decreasing their width. • High level memorization time up to dozens of µs is possible Output (a.u.) 3.2 mV Time (µs) www.com.dtu.dk

21. Thank you for listening! Questions and comments! www.com.dtu.dk