implementation issues in the optical router project
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Implementation Issues in the Optical Router Project. Isaac Keslassy, Da Chuang, Nick McKeown High Performance Networking Group klamath.stanford.edu. Switch fabric design. Design a switch fabric using a two-stage switch architecture 625 linecards of 160Gbps Features: Low power - PowerPoint PPT PresentationTRANSCRIPT
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High PerformanceSwitching and RoutingTelecom Center Workshop: Sept 4, 1997.
Implementation Issuesin the Optical Router Project
Isaac Keslassy, Da Chuang,Nick McKeown
High Performance Networking Group
klamath.stanford.edu
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Switch fabric design
Design a switch fabric using a two-stage switch architecture 625 linecards of 160Gbps
Features: Low power Reliability Arbitrary addition and deletion of linecards (due to
upgrades/failures) Scalability
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Given the set of features:
System Constraints
Maximize Total Capacity Cs.t. Rack Power: P < 5kW Rack Volume: V < 2m3
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Racks of linecards
Optical links
SwitchFabric
100Tb/s Router
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Two-stage reminder: spreading
R/N
Passive mesh
1
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1
23
R/NR/N123
123
Cyclic Shift Cyclic Shift
R R
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Possible Optical Components
Our bag of tricks: WGRs (wavelength determines routing) Tunable Lasers (transmitters) Tunable Filters (receivers) Star Couplers (broadcast-and-select) Traditional MEMs (mirrors)
Ideally, use a passive component: Less power Reliable
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WGR : A Passive Optical Component
Wavelength i on input port j goes to output port (i+j) mod N
Can shuffle information from different inputs
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WGR Based Solution (N=64)
1,
2
…N
1,
2
…N
1,
2
…N
NxN WGR
Laser/Modulator
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N
Linecard 1
Linecard 2
Linecard N
Detector
Linecard 1
Linecard 2
Linecard N
1,
2
…N
1,
2
…N
1,
2
…N
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N
12
N
12
N
12
N
12
N
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Problem 1: Missing Linecards
R/N R/NIngress
Linecard 1
IngressLinecard 2
IngressLinecard N
MidstageLinecard 1
MidstageLinecard 2
MidstageLinecard N
EgressLinecard 1
EgressLinecard 2
EgressLinecard NR/N R/N
R
R
R
R
R
R
R/2 R/2
R/2 R/2
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WGR
Features: Low power Reliability Arbitrary addition and deletion of
linecards (due to upgrades/failures)
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Solutions to Problem 1
Change data rate per lambda
WGRs of binary sizes with static MEMs
New device: programmable WGR e.g. if only 2 linecards,
• odd wavelengths -> port 0• even wavelengths -> port 1
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Problem 2: Scalability to 640 Linecards
Linecard 1
Linecard 2
Linecard W
WxW WGR
Linecard 1
Linecard 2
Linecard W
Group M
WxW WGR
Linecard 1
Linecard 2
Linecard W
Group 2
WxW WGR
Linecard 1
Linecard 2
Linecard W
Group 1
MxM
MxM
MxM
Linecard 1
Linecard 2
Linecard W
Linecard 1
Linecard 2
Linecard W
Group 1
Group 2
Group M
MEMS
MEMS
Additional spreading stage with MEMS
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WGR and MEMS
Features: Low power Reliability Arbitrary addition and deletion of
linecards (due to upgrades/failures) Scalability: N=640 linecards
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Possible Optical Components
Our bag of tricks: WGRs (wavelength determines routing) Tunable Lasers (transmitters) Tunable Filters (receivers) Star Couplers (broadcast-and-select) Traditional MEMs (mirrors)
Ideally, use a passive component: Less power Reliable
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Star Coupler: Another Passive Optical Component
Broadcast and Select Device all wavelengths on all input ports are broadcast to all output ports
Need tunable filter to select correct data
Collision can occur if two input ports use the same wavelength
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Star Coupler3x3
Star coupler
3x3Star coupler
3x3Star coupler
3x3Star coupler
Linecard 1
Linecard 2
Linecard 3
Linecard 4
Linecard 5
Linecard 6
(1, 1, 1)
(1, 1, 2)
(1, 2, 1)
(1, 2, 2)
(2, 1, 1)
(2, 1, 2)
(2, 2, 1)
(2, 2, 2)
(3, 1, 1)
(3, 1, 2)
(3, 2, 1)
(3, 2, 2)
Group 1
Group 2
Group 3
(1, 1, 1)
(1, 1, 2)
(1, 1, 3)
(1, 2, 1)
(1, 2, 2)
(1, 2, 3)
(2, 2, 1)
(2, 2, 2)
(2, 2, 3)
(2, 1, 1)
(2, 1, 2)
(2, 1, 3)
Linecard 1
Linecard 2
Linecard 3
Linecard 4
Linecard 5
Linecard 6
Group 1
Group 2
Group 3
(1, 1, 1)
(1, 1, 2)
(1, 1, 3)
(1, 2, 1)
(1, 2, 2)
(1, 2, 3)
(2, 2, 1)
(2, 2, 2)
(2, 2, 3)
(2, 1, 1)
(2, 1, 2)
(2, 1, 3)
(1, 1, 1)
(1, 1, 2)
(1, 2, 1)
(1, 2, 2)
(2, 1, 1)
(2, 1, 2)
(2, 2, 1)
(2, 2, 2)
(3, 1, 1)
(3, 1, 2)
(3, 2, 1)
(3, 2, 2)
Two spreading stages: space and wavelength
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Star Coupler
Features: Low power Reliability Arbitrary addition and deletion of
linecards (due to upgrades/failures) Scalability: N=640 linecards
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A Complete Solution3x3
Star coupler
3x3Star coupler
3x3Star coupler
3x3Star coupler
2x2
2x2
2x2
2x2
2x2
2x2
2x2
2x2
2x2
2x2
2x2
2x2
Linecard 1
Linecard 2
Linecard 3
Linecard 4
Linecard 5
Linecard 6
Group 1
Group 2
Group 3
Linecard 1
Linecard 2
Linecard 3
Linecard 4
Linecard 5
Linecard 6
Group 1
Group 2
Group 3
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A Complete Solution
Features: Low power Reliability Arbitrary addition and deletion of
linecards (due to upgrades/failures) Scalability: N=640 linecards
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Conclusion
WGR based solution is practical but not flexible
Star coupler based solution meets all requirements but is cumbersome
New optical components may help