Dense Wavelength Division
Multiplexed Interconnects for High
Performance Embedded
Computing Architectures
Aaron M. Cordes & Rick C. Stevens
Lockheed Martin
Mission Systems and Sensors (MS2)
Dense Wavelength Division Multiplexing (DWDM)
 DWDM fiber optic interconnects form the infrastructure for telco industry’s
high-bandwidth backbones
 Numerous advantages over electrical interconnects
 Extremely high data capacity (100’s of Gbps to 10’s of Tbps per fiber).
 Improved signal integrity leading to increased link distances.
 EMI immunity.
 The ability to increase data rates and add communications channels
without changing the cabling infrastructure.
 Lower-weight cabling.
 To date, environmental and packaging concerns have limited the applicability
in HPEC systems
l1
l1
l2
l2
Input Data
Transmitter 1
ITU Channel 1
Input Data
Transmitter 2
ITU Channel 2
Input Data
Transmitter 3
ITU Channel 3
Input Data
Transmitter 4
ITU Channel 4
l4
Input Data
Transmitter n
ITU Channel n
ln
l3
DWDM
Multiplexer
l1 ... ln
Erbium
Doped Fiber
Amplifier
l1 ... ln
DWDM DeMultiplexer
Receiver 1
Output Data
Receiver 2
Output Data
Receiver 3
Output Data
l4
Receiver 4
Output Data
ln
Receiver n
Output Data
l3
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Passive DWDM Networks
 Wavelengths are centered
around C-Band (1550 nm) or
L-Band (1595 nm)
 Spaced at 50, 100, or 200
GHz increments
 Conforms to ITU grid
 Passive combiners and
splitters permit full
connectivity between
endpoints
 Active components
isolated to Tx/Rx
endpoints
 Creates a passive, optical
broadcast interconnect that
is protocol and data-rate
agnostic
l1
l4
Endpoint 1
Endpoint 4
l1...lN
l2
Endpoint 2
l1...lN
l3
Endpoint 3
l1...lN
l1...lN
NxN
Passive Star
Coupler
lN
l1...lN
Endpoint N
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Application of Passive DWDM Interconnects to
HPEC Systems
 Additional endpoints can be added to system with no impact on
previously installed hardware
 Enables low-cost technology insertions
 Can carry multiple protocols on a single fiber at multiple
signaling rates
 10G Ethernet, 1G Ethernet, SRIO, Fibre Channel, Infiniband,
custom, etc.
 Allows I/O-challenged systems to push beyond their current
limitations
 Eliminates contention and blocking in the network
 All endpoints are assigned a unique wavelength for
transmission
 Allows new levels of sensor data sharing
 Data is inherently broadcast to all endpoints with no additional
overhead
 Eliminates the need for switching hardware, reduces SWaP
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Challenges of Passive DWDM Interconnects in
HPEC Systems
 Reduction of the SWaP envelope of the DWDM transmit and
receive endpoints so that they can be designed into standard
HPEC form factors such as PMC, XMC, and VPX.
 Hardening the active components against the temperature,
shock, vibration, and other environmental requirements
encountered in HPEC systems.
 Addressing Information Assurance (IA) and Multi-Level Security
(MLS) requirements by developing a secure passive
infrastructure for systems where data separation must be
provided.
 Developing endpoint firmware that leverages standard highspeed point-to-point protocols, such as Serial RapidIO or 10
Gigabit Ethernet, while updating them to support the DWDM
broadcast interconnect.
Lockheed Martin MS2 is actively addressing each of these challenges
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