Transcript 20050719-Nortel-Daspit

Terascale Network Technology Workshop
- Solutions for Lightpaths
- Architecture, Control and Cost
Kim Roberts, & Michel Belanger
Optical Systems
July 17, 2005
A LightPath
> A network connection that provides guaranteed capacity,
constant latency, and high reliability.
• Provisioned by a control plane.
• Megabits to Terabits per second
• The optimum implementation can be L0, L1, or L2, depending on
the capacity needed and facilities available
Layer 2 Packet
Layer 1 Transport
Layer 0 Photonic
2
Ethernet
OC-192
Photons
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Challenges in using Lightpaths
> Layer 0
Photons
• Need to make the connection independent of optical physics
• Need effective way of switching of lots of wavelengths – any to any
> Layer 1
OC-192
• Need to map efficiently into the appropriate bandwidth
• Need cost-effective switching of lots of STS-Ns
> Layer 2
Ethernet Connections
• Need to aggregate packets while preserving quality
• Need cost-effective management of lots of VLANs
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Summary: Lightpath Solutions
> Layer 0
Photons
• Have made the connection independent of optical physics
• WSS effective switch for lots of wavelengths
> Layer 1
OC-192
• GFP/VCAT/LCAS maps efficiently into the appropriate bandwidth
• OME and HDX effective switching for lots of STS-Ns
> Layer 2
Ethernet Connections
• L2SS aggregates packets while preserving quality
• L2SS, RPR provides cost-effective management of lots of VLANs
• RPR provides high reliability ring.
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Making Layer 0
Independent of Optical Physics
> What is wrong with physics?
> Solutions in CMOS
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Hurdle: Fiber Dispersion Management
TWc
SMF-28
TWc
ROADM
Photonic
Cross-Connect
E-LEAF
SMF-28
E-LEAF
Photonic
Cross-Connect
SMF-28
Photonic
Cross-Connect
E-LEAF
Bulk dispersion compensation will not suffice
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Effect of Dispersion
Transmitted Eye
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Eye after 320 km of Fiber
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Optical Nonlinearities
> Self Phase Modulation (SPM) arises from the Kerr effect,
where the amplitude of an optical signal changes its
phase.
• Rapid phase changes interact with chromatic dispersion to distort
high capacity optical signals.
> Cross Phase Modulation (XPM) is the similar effect
between channels.
> Other nonlinearities: Four wave mixing, SRS, SBS, MI
> Amplified Spontaneous Emission (ASE) is optical noise
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Issues with using present methods
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Dispersion Compensation Modules (DCM)
> Coils of 1 to 20 km of special fiber
> 3 to 9 dB of loss
> One module for C, another for L band
> $3k to $10k per module
> Different slopes for different fiber types
> Generally needed at each line amp site
• Depending upon fiber type, system topology, span lengths.
All the above still does not get us over the hurdle of
full agility or address multiple line rates
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Layer 0 Solutions
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Transmitter Pre-compensation
Tx
Digital
data
D/A
Optical
modulator
CD-1
D/A
0
laser
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
-30
12
Rx
-20
-10
0
10
20
30
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Recovered
data
Electronic Dispersion Compensation
320 km of G.652 fiber, 2.5 dBm launched
No Compensation
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Received Eye Diagram
320 km of G.652 fiber, 2.5 dBm launched
No Compensation
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WARP Compensation
Overcomes Dispersion
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10 Gb/s
with no Traditional Dispersion Compensation
0 Km
1600 km
3200 km
5120 km
Eye diagrams after transmission over standard G.652 fiber
with Nortel WARP processing.
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Forward Error Correction
to mitigate noise
Performance: Effective Coding Gain
> Wraptor corrects an error rate of 0.38% to < 10-16
> Increased system gain and improved burst tolerance
12.0
Shannon Bound @ 7% (~ 10.4 dB)
10.0
WRAPTOR
8.0
WRAP10
RS-8; 6.2 dB (G.975)
6.0
TRIFEC
4.0
2.0
0.5 um BiCMOS
600K gates
4.2 dB
BCH-3
FEC
Aug 1996
0.18 um CMOS
2M gates
7.4 dB; 7%
BCH-20
0.13 um CMOS
6M gates
9.2 dB; 7% OH
0
2000
16
2001
2002
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2003
3 dB
Simplified Optical Line  Enables Lightpaths
AMP Node
OADM Node
DCF
DCF
DCF
DCF
OEO
OEO
OEO
AMP Node
WSS Node
…
DCF
DCF
Demux
Terminal Node
DCF
Raman
OEO
DCF
Raman
DCF
Raman
Mux
OEO
…
OEO
…
DCF
Terminal Node
Demux
…
OEO
Mux
Terminal Node
OEO
OEO
Terminal Node
OEO
OEO
OEO
OEO
OEO
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Tom Di Pasquale
Optical Solutions
Paul Daspit
Advanced Technology Research