Panel : Next Generation Optical Transport Networks - From 100G to 1T and Beyond

Transcription

1 anel : Next Generation Optical Transport Networks - From 100G to 1T and Beyond April 19, 2011 Tom McDermott Fujitsu Network Communications

2 What is OTN? Optical Transport Network (OTN) ITU G.709 provides: 1. Standard wrapper for formats: 2.5G, 10G, 40G, 100G. Includes OAM, trace, FEC. Standard wrapper for 1GE into ODU0 (1.25G). Multiple payload mappings (SONET, Ethernet, FC, ODUflex: CBR, GF). 2. A switchable (cross-connectable) frame format. Granularity: down to ODU0 (1.25G). OTN has fast frame rate (compared to SONET 125 µsec). 10G= µsec; 40G= µsec; 100G= µsec. 3. rivate Line and Transparent Services. OTN Wrapping became pervasive for high-speed DWDM optical signals ~ last 5 years. Cross-connection typically used by operators with largescale networks. 1

3 Technology beyond 100G Today s ROADM systems channelized on 50 GHz spacing. Existing channels support: 100G / D-4SK. 200G / D-16QAM. OSNR limits span lengths. 400G / D-64QAM. OSNR imposes severe span shortening. 400G and 1T could be formed by: Inverse multiplexing 50G channels. Creating Super Groups - Enable different modulation types. OTN for higher rates probably should consider approaches beyond just frame-level multiplexing. 2

4 Capacity vs. Reach Tradeoff Gbit/s # ol. Gbaud Grid (GHz) Bits/ symbol Modulation D-QSK D-16QAM D-QSK D-16QAM >50 6 D-64QAM D-256QAM QAM 64QAM 256QAM ROSNR Copyright 2010 FUJITSU LABORATORIES LTD.

5 Higher Rate Channels 4 independent D-QSK 100G signals combined post-processing for 400G (Inverse Mux) 5 independent D-16-QAM 200G signals combined post-processing for 1T (Inverse Mux) Compatible with existing 50 GHz channelized optical line systems 50 GHz ROADM Channels Supergroup create multiple optical carriers each independently modulated: OFDM or N x Digital Variable ROADM Channels Using flexible-grid ROADM to create a Supergroup. May achieve higher Spectral Efficiency. 4

6 Circuits & ackets Switching and support for 1GE, 10GE, 100GE provide complementary approaches for router interconnect. -Routers provide aggregation and grooming of traffic. OTN devices proposed to provide partial or complete -router bypass. Reduce power and cost, minimize latency. However, bypass circuits are static unless C used. As link speeds increase to 400G, 1T, we may not need fine granularity for all links. 5

7 -Router Bypass 40G 60G -Routers aggregate traffic to share a few high-speed links among many -end points. -Router as transit device may or may not add value. 40G ODU OTN 60G ODU OTN can establish express-paths between -routers with ~1G bandwidth granularity. Advantage: simple, low-latency, lowerpower, fewer MLS hops. Disadvantage: relatively static unless Control lane used. OTN 3G ODU OTN OTN OTN can establish Mesh between routers with ~1G bandwidth granularity. Advantage: simple, low-latency, lowerpower, eliminate -routers. 5G ODU 1G ODU Disadvantage: potentially large number of circuits needed. Question: does OTN scale better or worse than MLS as links speeds continue to increase beyond 100G? 6

8 Summary OTN G.709 needs to accommodate multiple optical carriers per digital payload for growth beyond 100G. Multiple modulation formats may be needed to adjust span reach vs. spectral efficiency. N x 100G: best reach, worst spectral efficiency. Control lane needs to address: Wider range of optical formats. OTN concatenation / inverse-multiplexing. -Router bypass may become increasingly attractive at 400G and 1T. ower, latency. 7

9 Copyright 2010 FUJITSU LIMITED 8