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Upgrading Enterprise Data Centers with SWDM4

Small cloud and enterprise data centers want to upgrade their 10G Ethernet to 40G and 100G Ethernet without changing their duplex multimode fiber cabling infrastructure.


Shortwave Wavelength Division Multiplexing USE CASE

Upgrading 10G Ethernet to 40G & 100G without changing cabling infrastructre.
Small Cloud and Enterprise Data Centers.
Finisar's 40G and 100G SWDM4 Optical Transceivers.


Medium and large-sized Enterprises have been widely deploying 10G Ethernet for several years. The IT staff responsible for the installation and operation of their data centers are very familiar and comfortable with the technology, using duplex patch cords and their its associated LC connectors in the rack. However, Enterprises now want to upgrade their 10G Ethernet to 40G and 100G Ethernet without changing their duplex multimode fiber cabling infrastructure, all while maintaining the same supported link distances as 10G Ethernet. Leveraging existing fiber infrastructure appears would be preferable, due to CapEx and OpEx considerations. 

Block diagram of a 100G SWDM4 transceiver


As these data centers begin their transition to 40G and 100G Ethernet, enterprise IT architects have a choice to make:

  1. They could use 40GBASE-SR4 and 100GBASE-SR4 optical transceivers, which have become very cost-effective but require the use of parallel optics infrastructure. This means having to replace their duplex LC patch cords with their characteristic “clicking” sound to confirm proper latching, simple termination and cleaning, to parallel MPO patch cords that are less familiar. Also the installation of additional trunks/structured cabling would be required, since each full-duplex link now would require eight fibers instead of only two. This approach is not only CapEx-intensive, but also may increase OpEx substantially given the unfamiliarity of the IT networking personnel with the handling/cleaning of the MPO connector.
  2. The other option is to install single-mode fiber to continue to use the familiar duplex fiber/LC-connector paradigm. This means using 40GBASE-LR4 and 100GBASE-LR4 (or CWDM4) optical transceivers, which have a significantly higher cost than multimode SR4 transceivers. This is a very CapEx and OpEx-intensive approach, but has advantages of eliminating cost in IT personnel re-training to use the MPO connector, as well as substantially increasing the link distance (if that were a requirement). It could be argued that a potential additional advantage of this single mode option is the future-proofing of the infrastructure for deployments beyond 100G Ethernet. However, the IEEE is already standardizing multimode 400G interfaces suitable for the enterprise data center environment, which are expected to be available by the time most of that market segment is ready for the transition.

Neither of the options above are particularly attractive.


Pluggable optical transceivers with Shortwave Wavelength Division Multiplexing (“SWDM”) technology address this market need. Shortwave wavelength division multiplexing (SWDM) is a cost-effective means of transmitting multiple channels on one duplex multimode fiber pair. [See below for the technical details]

Finisar's SWDM4 transceivers enable the transmission of 40G (4x10G) and 100G (4x25G) over existing duplex multimode fiber. This means that data centers can upgrade their optical links to 40G and 100G leveraging their existing fiber infrastructure and still using the same familiar LC connectors instead of changing to MPO patch cords.

For new data center builds, SWDM4 requires 2 fibers like 40G/100G SR4. This significantly increases the bandwidth density per OM3/OM4 fiber and decreases the cost of new trunks/strutured cabling infrastructure, while still using cost-effective multimode transceivers. For larger data-centers, the new OM5 wideband multimode fiber can extend the reach of the SWDM4 optics, since it allows wavelengths up to 953nm to propagate further. For either existing ot new data centers using 40G/100G Ethernet, SWDM4 is a perfect solution to decrease infrastructure cost, and/or to increase link performance. Compared to proprietary "BiDi" technologies, SWDM4 supports longer link lengths and simplifies network monitoring. 



Increasing Bandwidth Density in New Data Center Builds

In addition to the “brownfield” application already described, enterprise users who deploy 40G and 100G SWDM4 interfaces instead of parallel optics in their new data centers will require two fiber strands per full-duplex link instead of eight. This architecture significantly decreases the CapEx required for new trunk/structured cabling infrastructure, while still enabling the use of cost-effective multimode optical transceivers.

Supported Reaches for Data Center Upgrades and New Builds

40G SWDM4 QSFP+ transceivers can support up to 300m on OM3; 400m on OM4 legacy multimode fiber; and 500m on OM5 multimode fiber.
100G SWDM4 QSFP28 transceivers can support up to 100m on OM3 and 150m on OM4 legacy multimode fiber; and 180m on OM5 multimode fiber.

Contact us to upgrade your data center today.

SWDM4 Wavelengths as defined by the SWDM MSA

What is SWDM4?

The approach consists of multiple VCSELs operating at different wavelengths in the 850nm window, where multimode fiber is optimized. The four-wavelength implementation of SWDM is called SWDM4, and these four wavelengths are multiplexed/demultiplexed inside the QSFP transceiver into a pair of multimode fibers (one fiber in each direction, for example a standard duplex interface. Each of the four wavelengths operates at either 10G or 25G, enabling the transmission of 40G (4x10G) or 100G (4x25G) Ethernet over existing duplex multimode fiber, using standard LC connectors. This is a similar approach to what is done in LR4 and CWDM4, but optimized for multimode fiber, plus VCSELs are a lower cost technology.

Up to 500m for 40G and 180m for 100G
Power Dissipation
As low as 1.5W*
Ability to easily tap for network security appliances
Full DDM
Including Tx power monitoring
Operational and measurement simplicity – single Tx and Rx ports

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