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OPTICAL TRANSPORT NETWORKS: FROM ALL-OPTICAL TO DIGITAL. ITU-T Kaleidoscope 2009 Innovations for Digital Inclusion. Virgilio Puglia virgilio.puglia@tin.it Olga Zadedyurina olga.zadedyurina @disi.unitn.it. Outlines. Traditional DWDM based on OTN (Optical Transport Network) ITU-T G.872;
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OPTICAL TRANSPORT NETWORKS: FROM ALL-OPTICAL TO DIGITAL ITU-T Kaleidoscope 2009Innovations for Digital Inclusion Virgilio Puglia virgilio.puglia@tin.it Olga Zadedyurina olga.zadedyurina@disi.unitn.it
Outlines • Traditional DWDM based on OTN (Optical Transport Network) ITU-T G.872; • IPoDWDM; • ODN (Optical Digital Network);
Introduction • IP traffic today becomes dominant: • New application based on IP (video communication, P2P, etc.); • Old application migrate to IP (ex. SS7); • IP traffic has overcome capacity of currently used wavelength 10Gb/s; • Today trend/evolution is: • Eliminate SDH/SONET layer; • Move Transport from Optical to Digital;
Traditional DWDM as an OTN • DWDM is a fully optical network which provides transparency: • only 1R regeneration (optical amplification-equalization and CD compensation); • theoretically the signal can be delivered from every ONE to any other. • Traditional (OTN) approach becomes hardly realizable for big network;
IPoDWDM Approach • Insert IP traffic into DWDM without mapping into SDH frame; • Integration of DWDM transponders directly into IP switch/router. OTN G.709 Transponder IP routers Transponder Transponder Transponder IPoDWDM G.709 Transponder IP routers Colored interface Transponder MUX Transponder Gray interface
IPoDWDM intelligence BER BER FEC Limit Corrected bits Optical Impaiments Preemptive traffic protection becomes possible IPoDWDM OTN Lost data Working path Protection p. Work path Protection path POS on router LOF IP Layer IP Layer + G.709 on router FEC Limit SDH/DWDM Layer Corrected bits Transponder Switch threshold Optical Impaiments
Optical Digital Network Approach • The philosophy of ODN is based on O-E-O conversion whenever it is possible. • OTN manipulate analogical wavelengths; • ODN manipulate digital “bits”.
Network Layers: OTN vs ODN IP ATM Ethernet STM-N IP ATM Ethernet STM-N OTN ODN Optical Channel Payload Unit (OPU) Optical Channel Payload Unit (OPU) Optical Channel Data Unit (ODU) Optical Channel Data Unit (ODU) Digital Digital Optical Channel Transport Unit (OTU) Optical Channel Transport Unit (OTU) Optical Digital Channel (ODCh) Optical Channel (OCh) Optical Multiplex Section (OMS) Band Multiplex Section (BMS) OTM0 Physical Section (OPSO) OTM0 Physical Section (OPSO) Analog Optical Transmission Section (OTS) Optical Transmission Section(OTS) Analog Optical Transport Module (OTM-n, n>1) OTM0 (not colored, no OSC) OTM0 (not colored, no OSC) Optical Transport Module (OTM-n, n>1)
ODN advantages • Each OADM site implements 3R regeneration: • the signal is cleaned up from noise and others distortion; • It becomes possible to implement higher number of Channels -160 (C band, spacing 25 GHz); • The network lose transparency.
ODADM Description O-E O-E O-E O-E O-E O-E Electrical connection Optical connection Optical pass-through MBM FEC Digital W. DSP FEC Digital W. DSP MBM East Line West Line O-E O-E Optical Spliter Matrix Matrix O-E Optical Spliter O-E O-E O-E O-E O-E To interface modules To interface modules Specific Interface Module
RECONCILATION BETWEEN THEAPPROACHES • To integrate different approach the existing OTN network must support Alien Wavelets (ITU-T G.698.2) • IPoDWDM is easy to integrate into OTN; • IPoDWDM is easy to integrate into ODN but not efficiently; • ODN can be integrate into OTN using an optical band split filter.
Example of ODN-OTN integration 50Ghz-100Ghz Filter 50Ghz-100Ghz Filter • The majority of deployed DWDM networks are equipped with 100GHz lambda spacing while transponders have stability for 50GHz spacing. C-Band ODADM Even frequencies 100 Ghz East Line 192.5 192.3 192.1 192 192.2 192.4 192.6 West Line 100 Ghz C-Band ROADM 192.05 192.25 192.45 192.65 192.75 192.15 192.35 192.55 Odd frequencies
Capacity Evolution • 10 Gb/s ->40 Gb/s ->100 Gb/s - CD increases and PMD appears; • ODN and IPoDWDM: - the limit of 160 channels (L+C band) • ODN: - due to E-O-E no dispersion problems. - granularity of PIC is inflexible parameter (today either 10 or 40 Gb/s based) New capacities are being studied by IEEE 802.3ba G.698.2 should standardize new interfaces
Conclusions • OTN, IPoDWDM, ODN approaches analyzed; • IPoDWDM and ODN are seen as very promissing; • Examples on integration of both technologies; • Stimulus for further research and standardization activities;
Back up • The following slide are for back up
OTN Network Elements Client (not terminated in OADM site) Och (not terminated in OADM site) • OLT (Optical Line Terminal) • OADM/ROADM (Optical Add Drop Multiplexer) also Reconfigurable • OLA (Optical Line Amplifier) • OXC (Optical Cross-Connect) OMS OMS OTS OTS OTS OTS OTS OLT OLA OLA OADM OLA OLT
IPoDWDM Network Elements OPU - Optical Channel Payload Unit ODU - Optical Channel Data Unit OTU - Optical Channel Transport Unit Client-OCh-OTU-ODU-OPU (yellow & green lambda) IP Router Client-OCh-OTU-ODU- OPU(red & blue lambda) Client-OCh-OTU-ODU-OPU (red & blue lambda) OMS OMS OTS OTS OTS OTS OTS G.698.2 “black-link” Optical colored interface DWDM MUX/DMUX OCh - Optical Channel OMS - Optical Multiplex Section ONE - Optical Network Element OTS - Optical Transmission Section Optical fibre Optical Line Amplifier
ODN Network Elements Client OPU ODU OTU OTU ODCh ODCh BMS BMS OTS OTS OTS OTS OTS DNE DNE DNE OPU - Optical Channel Payload Unit Electrical connection ODU - Optical Channel Data Unit Optical connection OTU - Optical Channel Transport Unit DNE - Digital Network Element OLA (Optical Line Amplifier) ODCh - Optical Channel BMS - Band Multiplex Section MBM (Multiplexing Band Module) OTS - Optical Transmission Section