Transcript Presentation Title

Next Gen ROADMs
“Less” is more:
Colorless, Directionless, Contentionless, Gridless
Krishna Bala, Ph.D
Exec VP WSS Group
[email protected]
ECOC 2010 Turin Italy
Company Confidential
1
Outline
• Next- Gen ROADM requirements
• Architectural Choices
• Implications for WSS devices
Company Confidential
2
Generations of ROADMs
• 1st Gen ROADMs introduced the following features:
– Re-configurability in add/drop channels
– However, these nodes were restricted to 2 directions
• 2nd Gen ROADMs introduced the following features:
– Multi-degree capability (e.g. 4 or 8 directions per node)
– However, these nodes are “colored” and “directional”
• 3rd Gen ROADMs will introduce more “Mesh” features:
– Significant flexibility in provisioning and restoration
– Colorless, Directionless, Contentionless and “Gridless” (Flexible
Spectrum actually)
Company Confidential
3
2nd Gen ROADM: 8 degree example
Colored and Directional
8x1 WSS
Degree 2
Passive
splitter
Degree 8
Degree 1
8x1 WSS
AWG
AWG
AWG
AWG
Tx
Colored:
Directional:
AWG
Add/Drop
8x1 WSS
AWG
Rx
Each “chassis slot” is associated with specific “laser color”
Each laser is associated with a specific direction
Company Confidential
4
Requirements for 3rd Gen ROADMs
New Features for Mesh ROADMs/WSS
North In
North Out
East In
West In
ROADM Node
East Out
West Out
Local Add ports
Local Drop ports
• Colorless add/drop – No blocking in
wavelength assignment on any Add/Drop
• Directionless add/drop – Full flexibility in
routing to any direction
• Contentionless add/drop – No blocking
inside ROADM due to wavelength collision
• Gridless - Dynamically allocate
spectrum to each wavelength
Company Confidential
5
Requirements for 3rd Gen ROADMs
New Features for Mesh ROADMs/WSS
North In
North Out
East In
West In
ROADM Node
East Out
West Out
Local Add ports
Local Drop ports
• Colorless add/drop – No blocking in
wavelength assignment on any Add/Drop
• Directionless add/drop – Full flexibility in
routing to any direction
Of course, customers want ……. Costless 
• Contentionless add/drop – No blocking
• Gridless - Dynamically allocate
As
a
supplier,
we
think
…………..
Priceless 
inside ROADM due to wavelength collision
spectrum to each wavelength
Company Confidential
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3rd Gen ROADM: 8 degree example
Adding Colorless Feature: Replace AWGs
8x1 WSS
Degree 2
Passive
splitter
Degree 8
Degree 1
8x1 WSS
AWG
AWG
AWG
AWG
Tx
Colored:
Directional:
AWG
Add/Drop
8x1 WSS
AWG
Rx
Each “chassis slot” is associated with specific “laser color”
Each laser is associated with a specific direction
Company Confidential
7
3rd Gen ROADM: 8 degree example
Colorless
8x1 WSS
Degree 2
Degree 1
8x1 WSS
Degree 8
Passive
splitter
AWG
1x24 WSS
AWG
1x24 WSS
AWG
1x24 WSS
AWG
1x24 WSS
Tx
Colorless:
Directional:
1x24 WSS
AWG
1x24
WSS
Add/Drop
8x1 WSS
Rx
Each “chassis slot” can associate with any “laser color”
Each laser is associated with a specific direction
Colorless: Requires “Scalability” in WSS port count – Large port count
Company Confidential
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3rd Gen ROADM: 8 degree example
Colorless AND Directionless
8x1 WSS
Degree 2
Degree 1
8x1 WSS
Degree 8
Passive
splitter
Passive
splitter
8x1 WSS
8x1 WSS
AWG
1x24 WSS
AWG
AWG
1x24 WSS
1x24 WSS
1x24 WSS
Add/Drop
8x1 WSS
AWG
1x24 WSS
1x24 WSS
Tx
Company Confidential
9
3rd Gen ROADM: 8 degree example
Colorless and Directionless: But, has Contention
8x1 WSS
Degree 2
Degree 1
8x1 WSS
Degree 8
Passive
splitter
Contention
8x1 WSS
8x1 WSS
AWG
1x24 WSS
AWG
AWG
1x24 WSS
1x24 WSS
1x24 WSS
Rx
Tx
Company Confidential
Add/Drop
8x1 WSS
AWG
1x24 WSS
1x24 WSS
Rx
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3rd Gen ROADM: 8 degree example
Colorless, Directionless, Contentionless
8x1 WSS
Degree 2
Degree 1
8x1 WSS
Degree 8
Passive
splitter
8x1 WSS
MxN WXC
24x8 or
48x8 or ….
8x1 WSS
AWG
1x24 WSS
AWG
AWG
1x24 WSS
MxN WXC
8x24 8x1
orWSS
8x48 or ….
1x24 WSS
1x24 WSS
Rx
Tx
AWG
1x24 WSS
1x24 WSS
Rx
Contentionless: Requires “Scalability” in WSS ports – Large port counts
Company Confidential
11
3rd Gen ROADM: 8 degree example
Colorless, Directionless, Contentionless with “Grouping”
8x1 WSS
Degree 2
Degree 1
8x1 WSS
Degree 8
Passive
splitter
8x1 WSS
MxN WXC
8x18x8
WSS
AWG
1x24 WSS
MxN WXC
8x1 WSS
8x8
8x1
WSS
AWG
AWG
1x24 WSS
1x24 WSS
1x24 WSS
Rx
Tx
Company Confidential
AWG
1x24 WSS
1x24 WSS
Rx
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3rd Gen ROADM:
Colorless, Directionless, Contentionless and “Gridless”
Example: Add BW in 25GHz steps
-200
-175 -150
-125 -100
-75
-50
-25
0
25
50
75
100
125
150
175
200
Dynamic/Flexible Spectrum Addition
– Add BW in 25 Ghz steps
– Allows future-proofing for higher speed transport
– E.g. 400 Gb/s and 1 Tb/s
Gridless: Requires Spectrum “Flexibility” in WSS
Company Confidential
Xtellus Confidential - 13
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WSS Roadmap for 3rd Gen ROADMs
• WSS must be SCALABLE
– Large port counts
• 1x24 plus ports and beyond
• MxN where M=8 and N=24 and beyond
• WSS must be FLEXBILE
– Dynamic/Flexible Spectrum Alloction
• Other “Must Haves”
– Fast switching speed: Fast mesh restoration
– Green: Low power dissipation
Company Confidential
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Conclusion
• 3rd Gen ROADMs require new features
– Colorless, Directionless, Contentionless,
Gridless
• 3rd Gen WSS must support
–
–
–
–
Scalability in port counts
Flexibility in spectral allocation
Fast switching times
Green low-power operation
Company Confidential
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