Optical Packet Switching the technology and its potential role in future communication networks Results from IST project . Lars Dittmann COM – Technical University of Denmark ld@com.dtu.dk 1 ld@com.dtu.dk Zagreb 210503
What is the next generation photonic network? (different targets different timescales) • Extension to current SDH/SONET network with LCAS, ASON, GMPLS, GFP, etc. ? • Bitrate and protocol transparent optical datapath with electrical control and management ? • All-optical network with optical control, information processing and routing ? 2 ld@com.dtu.dk Zagreb 210503
Why do we need the next generation optical network ? • for cost reduction reasons (cost reduction potential seems larger for optics than for electronics) • to increase network efficiency and utilisation • for resource savings preserving network reliability and availability • for better network control for fast and efficient configuration of connections (reduction of manual interventions) • to increase network flexibility and responsiveness to dynamic traffic demands/changes • because an optical network is in line with a simplified core structure with more complex and intelligent flow handling at the edges (which was the original idea of the MPLS concept) 3 ld@com.dtu.dk Zagreb 210503
Technological challenges possible optical connection types Network Resources Circuit Switching Packet and Burst Switching Connection Virtual Connection Oriented Oriented Virtual Leased Lines Leased Lines & VPNs Connection- Less Burst Packet Switching Switching 4 ld@com.dtu.dk Zagreb 210503
Technological challenges packets vs. circuits 10s Circuit 1s Flow 100ms Transfer Time 10ms 1ms 100 µ s Burst s s s p p p b b b G G G 10 µ s 5 0 0 . 2 1 4 e t a r t i B 1 µ s Packet 100ns 100 1k 10k 0.1M 1M 10M 0.1G 1G Transaction Size (Bytes) 5 ld@com.dtu.dk Zagreb 210503
Why packet switching • Primarily a traffic engineering tool! • Seen as the final goal for network flexibility, however must be justified • Packet based operation at application level and transport level should not be mixed up! • Potential new methods for network resilience in packet based networks (path set-up without resource reservation) 6 ld@com.dtu.dk Zagreb 210503
Optical Burst and label Switching potential step towards optical transport plane Control plane interface O E Switch Control (Label Swap) E O Labels in Labels out Add/Drop control Switch control � c � c In Fibre Out Fibre � 1 � 1 Optical Demux 1 � 0, � 1,..., � n Mux 1 � 0, � 1,..., � n WDM WDM Space � n � n Add/Drop Switch Drop Ports Add Ports Electrical Domain Burst Assembly/Disassembly Optical Domain Buffering O/E Conversion Data interfaces IP Router 7 ld@com.dtu.dk Zagreb 210503
• DAVID = D ata a nd Voice I ntegration over D WDM • A European research project – Financially supported by the EU commission – IST program • Goals – Develop concepts and technologies for future, optical networks – Traffic engineering in packet-over-WDM based networks – Control systems for optical networks • Timeline – Start July 2000, end October 2003 8 ld@com.dtu.dk Zagreb 210503
DAVID Project partners • Companies • Universities – Alcatel, CIT (F) – NTUA (G) – Alcatel, SEL (D) – University of Bologna (I) – Politechnica de Torino (I) • Network operators – LRI (F) – BT (UK) – INT (F) – TELENOR (N) – University of Essex (UK) – TELEFONICA (E) – UPC (E) • Research centers – IMEC (B) – COM (DK) 9 ld@com.dtu.dk Zagreb 210503
Overall architecture • Key components MAN – OPADM – optical packet add / drop multiplexer – Hub WAN – Gateway – OPR – optical packet router • Coverage – MAN and WAN • Control – MPLS-based 10 ld@com.dtu.dk Zagreb 210503
Hierarchical MPLS concept • An MPLS based architecture for mixed-technology networks • Traffic optimized/conditioned between levels • Levels of various granularity Level Bandwidth granularity Electrical MPLS Packets Optical MPLS Larger packets Wavelength Wavelengths routed + wavelength bands, fibers 11 ld@com.dtu.dk Zagreb 210503
The optical packet MAN Hub • Topology - interconnected physical DWDM rings • Each physical ring -> several logical rings OPADM OPADM • Ring nodes – OPADMs - provide – Ring connectivity – Legacy network interfaces • Inter ring traffic controlled by a hub � 0 o t a s l a t d d a t data slot a s l o t � 1 l o t a s d a t d a t a data slot s l o t W id e A re a N e tw o r k ... � � o t a s l d a t d a t data slot a s l o t O p tic a l M a n a g e m e n t o f th e s w itc h flo w s IP , E th e rn e t, ... R N 5 M A C p ro to c o l M u lti-rin g s IP , E th e r n e t, ... D w d m R N 1 W a v e le n g th b a n d s O p tic a l p a c k e ts O P A D M & le g a c y in te rfa c e s B a n d d e m u x B a n d m u x O p tic a l p a c k e t A d d /D ro p m u l ti p l e x e r ( O P A D M ) 12 L e g a c y i n te rfa c e ld@com.dtu.dk Zagreb 210503 IP , E t h e r n e t, ...
The metro part: MAN • Hub functionality: – each timeunit Hub switches traffic between rings – permutations to switch multislots between (logical) rings – permutations to use are based on measurements of "demand" ring 1 ring 1 ? ? ? ? ? ring 2 ring 2 ring 3 ring 3 ring 1 ring 1 ring 4 ring 4 ring 2 ring 2 slot ring 3 ring 3 1 2 3 1 3 3 ... ring 4 ring 4 input ring 2 3 4 3 2 1 ... 3 4 1 2 1 2 ... 4 1 2 4 4 4 ... ring permutation 13 ld@com.dtu.dk Zagreb 210503
Packet formats For synchronisation reasons fixed size packets (at transport level) is preferable for small units (nano-micro sec). Variable service units handled by sequence of fixed size packets. 14 ld@com.dtu.dk Zagreb 210503
Ring node evolutionary steps (cost vs. flexibility) DAVID MAN with passive DAVID MAN with passive DAVID MAN with passive DAVID MAN with passive DAVID MAN with active OPADMs OPADMs OPADMs OPADMs OPADMs “Now” “Future” 15 ld@com.dtu.dk Zagreb 210503
Administrative challanges ASON vs. GMPLS/MP � S • Apply the dynamic configuration of service layers to the transport layer(s) • Integrated control of layers in the network • Optimised use of the individual layers • Standard proposals from: IETF, ITU-T, OIF • Protocol centric solutions (IETF) vs. architectural centric solutions (ITU-T) • Multi-layer resilience concepts 16 ld@com.dtu.dk Zagreb 210503
Administrative challanges IETF : MPLS/MP � S level 3 (MP � S) (OMPLS) level 2 WAN WAN WAN WAN (EMPLS) level 1 level 0 (MAN) edge edge edge edge MAN MAN MAN MAN router router router router Technology hierarchy 17 ld@com.dtu.dk Zagreb 210503
When will the next generation of photonic networks become a reality • Significant effort needed to lower the cost and enable OAM functions of optical components (higher integration and automatic packaging) • Better understanding of traffic and performance issues in core and metro networks needed to evaluate cost and reliability issues in current proposals. • Gain consensus on administrative concepts and standard. • Optical networks must become digital – 3R in all elements as first process 18 ld@com.dtu.dk Zagreb 210503
When will the next generation of photonic networks become a reality • Dynamic administration of pseudo optical networks (SONET/SDH) in 2-4 years. • All-optical networks functions in the data plane obtainable in 5-10 years • All-optical operation in all layers is not realistic with current know technology (and might never be) 19 ld@com.dtu.dk Zagreb 210503
IST DAVID info @ david.com.dtu.dk Public demo in October in relation to Public demo in October in relation to PS´2003 (photonics in switching) in Paris PS´2003 (photonics in switching) in Paris and (NGPN deliverables @ www.ngni-core.net) 20 ld@com.dtu.dk Zagreb 210503
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