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Reconfigurable Optical Networks
using WSS based ROADMs
Steven D. Robinson
VP, Product Management
[email protected]
 Five Essential Elements of the NG Optical Network
. . . moving from static networks to dynamic networks
 What does a ROADM do? Which type is better?
 Key Technologies for 3rd Generation ROADM systems
 OEO vs. All Optical ROADMs
 Digital ROADM Hybrid Solution
 Intelligent Electrical & Optical Switching
Five Essential Elements of
Next Generation Optical Networks

Reconfigurability
 Simple, Flexible, Self Maintaining Systems

Pay as You Grow Scalability
 Start with 1 , grow by 1 
Seamless upgrade to 100G (efficiently)

Aggregation & Sub- Switching
 Integrated “ADM-on-a-blade”, High BW efficiency

Multi-Degree Operation
 Both Optical & Electrical Multi-degree Options

Automated Network Planning
 One time Node Engineering, GMPLS Control
Plane & True “Point-and-Click” Provisioning
and Management Systems
ROADM
OPM
O
P
M
ADM
ADM
Mux
Mux
Design Networks
in Minutes
West
East
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Up to 16 degrees
What is a ROADM?
Reconfigurable Optical Add/Drop Multiplexer (ROADM)
ROADM
Module
ROADM
Module
O
P
M
DROPs
ADDs
Key attributes of ROADM Module

Fully Flexible, Remotely Reconfigurable Optical Add Drop

Automatic power equalization on inputs, outputs, adds, drops

Optical Power Monitoring (OPM) of all channels
Key benefits of ROADM Module

Elimination of the OEO “Pass-through” tax

Scaleable Bandwidth (Start with 1 , grow by 1 )

Single Wavelength Granularity – No stranded bandwidth

Fully Automated Optical Layer

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WDM Optical Transport Technology Options
WB Module
Add Filters/
Combiner
O
P
M
Splitter /
Drop filte
rs
2 Degree ROADM
Blocker/IPLC
with fixed filters
OPM
Fixed Port
ROADM
Per 
OEO Regen
Optica
Multi-port
Mux/Demux
l Switc
h
OPM
(Point-to-point
DWDM)
Multi-Degree WSS
with fixed filters
OPM
Fixed
drops
Per
FOADM

Fixed
Adds
Optical Swit
ch
Multi-port Mux/Demux
OPM
O
P
M
Fully Flexible
Multi-degree
ROADM
Drops
Multi-Degree WSS ROADM
with colorless ports
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Which ROADM Technology is best?
Full Flexible, WSS based ROADMs
Wavelength Selective Switch (WSS) ROADM:

Utilizes a single element to multiplex AND demux all express and all add/drop wavelengths

Contains a built-in Optical Switch which can direct/select one or more wavelengths to/from any port

Provides Automated, per channel equalization on all wavelengths

Typically includes full Optical Power Monitoring on all wavelengths

Can be configured for truly colorless ports for widely tunable lasers & dynamic wavelength
management

Can be modular (low first in costs) or fully installed on day one
MP-WSS
WSS
Key
* Manages all wavelengths
Features:
* Lower system cost
* No OEO Pass-thru tax
O
P
M
* Fully Flexible Ports enable:
 Any wavelength to any port
Flexible
Drops
Flexible Adds
 Supports Tunable lasers
 Dynamic  Management
1
3
4 5 + 7
 Jumper-less provisioning
* Multiple wavelengths/ drop port
ROADM MODULE
 Mesh node capability
 Ring interconnection
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Key Technologies used in Core
Reconfigurable Networks
True Point-and-click
Planning & Provisioning
Rapid
Automated Network
Planning
and End-to-End
Management
GMPLS
Control Plane
Fully Flexible WSS
ROADMs
Widely Tunable
Lasers
Fully Automated
Optical Layer
Integrated Platforms
Multi-Service
ADM-on-a-blade
Flexible, Transparent
Optical Interfaces
Integrated Optical Cabling
Cross  Optical Switch
w/ Integrated. Transport
AGC / Transient Controlled
Optical Amplifiers (OAs)
Hot- Pluggable
SFPs & XFPs
Ethernet Networking
ROADM Systems provide much more than just Wavelength Reconfigurability
They provide a total “Agile Optical Network” Solution
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Why do customers like “All optical”
Source
1 2 3
13
14
15
16
17
18
19
20
21
21
1-12
All Optical ROADM : 42 Transponders
12
1
1
1
1
1
1
1
1
1
21
ILA
All OEO or “Digital Transport”: At least 380 Transponders
21 20
20 19
19 18
18 17
17 16
16 15
15 14
14 13
13 12
12
ILA
7

OEO becomes more expensive as the node count goes up
(# Regens x # nodes)

OEO becomes more expensive as the number of
wavelengths increases (# WL x # Regens x #nodes)

Use of Analog Optical Amplifiers lowers cost – unless you
need to drop traffic
6
Relative Cost, $
21
5
4
3
2
1
0
All Optical
All OEO
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OEO or ROADM
Which is the better choice?
Bit Rate
40 Gb/s
10 Gb/s
ROADM
ROADM
OEO
ROADM
OEO
2.5 Gb/s
2
4
6
8
10
12
14
16
18
Number of Pass-Thru Channels
Decision depends on:

Bit Rate; Number of Wavelengths

Topology & Traffic Patterns

Switching Need (which determines # of pass-thrus vs # of drops)

Size (# nodes and span length)  Amplify? Regen?

Total Cost of Ownership (OPEX vs. CAPEX)
Confidential
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Integrated OEO (Digital Transport)
Multi-Service & Investment Protection Issues
Integrated Tx
10 x 10G 
Integrated Rx
OEO Regen
OEO Regen
OEO Regen
OEO Regen
100%
90%
80%
70%
60%
50%
40%
4 x 10G
30%
20%
10 x 10G
10%
0%
ATM
ESCON
FC1
GbE
FC2
OC-48
10G
40G
100G
Integrated 10G OEO:
 Optimized for 10G client transmission
 Other services require muxing or inverse muxing (no transparent transmission)
 Support for native 40G or 100G will require ripping out OEO fabric
Confidential
8
Multi-degree ROADM or OEO?
Why be forced to choose?
All Optical ROADM Advantages:
OEO Advantages:


Sub-Wavelength Switching

Per wavelength Scaleable
1  2   . . . 40 
Potentially Lower Terminal Costs
(at full capacity)

Simpler Optical Engineering

Lower Power

Simpler Multi-Degree Operation

Fully Automated Optical Layer

Low Pass-thru costs

Fully Bit Rate Transparent
1G  10G  100G
Multi-Degree
ROADM Switch
100G
40G
10G
10G
2.5G
2.5G
Per WL OEO
Switch
Multi-Degree
OEO Switching
Digital ROADM
Node
Confidential
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Digital ROADM Hybrid Node
Lowest Overall Cost & Flexibility
All Optical
ROADM
Multi-Degree
All Optical
ROADM
100G
40G
10G
10G
2.5G
2.5G
Multi-Degree
Digital
Switching
TR
Digital
ROADM
Node
All Optical
Spur
Maintain manageable regions of transparency
7
Relative Cost, $
TR
Per WL
OEO
Switch
6
5
4
3
2
1
0
All Optical
Digital
ROADM
Hybrid
All OEO

Topology Agnostic

Traffic Pattern Agnostic

Bit Rate Agnostic

Simpler Optical Engineering

Simpler Multi-Degree Operation

Lower overall cost solution
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Intelligent Optical & Electrical Switching
Optical Drop
Wavelength
WSS
ROADM
(Optical
Switch)
Electrical
ADM
Drop/Add
1 GbE
Add
6 GbE
Electrical
ADM
Cross-WL
Optical Switch
with integrated
WDM
Switching Options:
• Pass Thru Entire Wavelength
Transponder
with Electrical
ADM Switch
ADM
ADM
Mux
Mux
• Optically Add/Drop Entire Wavelength
• Optically Add/Drop Multiple Wavelengths (Multi-degree)
• Electrically Add/Drop on a per Service Basis
• Add/Drop Multiple Services/Wavelengths for
Cross Wavelength Grooming & Multi-degree Switching
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ROADM Networks Summary
 Customers have recognized that low OPEX is now just as important
as the lowest CAPEX
 ROADM Modules are just one part of realizing the Next Generation
Agile Optical Network
 Other technologies such as automated planning tools, widely
tunable lasers, optical backplanes, Pluggables, and GMPLS
can dramatically simplify planning, operation & management
 Selection of the right kind of ROADM is crucial to realizing these
savings (Colorless Port, modular, WSS based ROADMs are the best choice)
MP-WSS
WSS
O
P
M
Flexible
Drops
Flexible
Adds
 These systems must be designed from the ground up to realize their
full potential (Bolt-on ROADMs don’t work)
 Digital ROADM Hybrid Solution may offer the best flexibility and
lowest overall cost
100G
40G
10G
10G
2.5G
2.5G
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Confidential