Transceiver Trends in DCs – How to connect them?

Transceiver Trends in DCs – How to connect them?

the main purpose of the IT Cabling Infrastructure within Data Centers is to interconnect active equipment (Switches, Servers, Storage etc..) with each other. Most of this active equipment accommodate nowadays pluggable Optical Transceivers as interface. Therefore – a bit simplified – the IT Cabling Infrastructure means connectivity between Transceivers.

For this reason it is important to understand what kind of Transceivers are today dominating the market and maybe even more important – what is the next generation. At the end of the day, the Transceivers define the connectivity needs.

SFP type Transceiver

SFP (Small Form Factor Pluggable, also SFP+ / SFP28) type of Transceivers are for long time in the market and cover a wide range of Ethernet & Fiber Channel applications. For 1000BASE-T and 10GBASE-T they have an RJ45 Copper Twisted Pair interface. However for Data Centers the optical versions starting with 10GBASE-SR/LR are much more important. There are a lot of ongoing dynamics and the latest high-speed versions are for 25GBASE-SR and 50GBASE-SR (PAM4 coding) on Multimode and up to 100, 200 or even 400 GBit on Singlemode fibers using WDM technologies for enlarged distances. Most SFP fiber Transceivers have an LC Duplex Connector interface and therefore this is a widespread connectivity within Data Centers. However, because of several advantages, latest trends are going towards QSFP Transceivers.

QSFP type Transceiver

QSFP (Quad Small Form-F. Pluggable, also QSFP+, QSFP28, QSFP56) type of Transceiver support parallel optical transmissions as required by various SR4 Ethernet standards like 40GBASE-SR4, 100GBASE-SR4, 200GBASE-SR4 etc. They have an MTP®/MPO optical connectivity interface with 8 active fibers – 4xTX & 4xRX (the footprint is an MTP®/MPO-12, but as only 8 fibers use, the connectivity is called MTP®/MPO-8).

QSFPs are ideal to create very effective Port-Breakout configurations, what means to operate the 4 lanes as separated channels and to link them to 4 SFPs, what, just as an example, allows to connect to one Switch slot 4 Servers. Port Breakout configurations are very cost effective and therefor popular, because they save space on the switch side and are also very effective with regard to low power consumption.

QSFP-DD & OSFP Transceiver

The latest generation of QSFP-DD (QSFP Double Density) and OSFP (Octal Small Form-F. Pluggable) are supporting so-called SR8 Multimode applications like 400GBASE-SR8. For that they provide an MTP®/MPO-16 connector interface for 8x TX and 8x RX. In order to guarantee the low noise requirement for PAM4 coded protocols, also the Multimode versions are with an APC (Angled Physical Contact) interface. Singlemode DR4 versions need by default MTP®/MPO-8 APC optical connectivity.

The QSFP-DD and OSFP footprints are also considered for the next generation 800 GigaBit Ethernet standards, which are currently in progress.

The SR-8 versions support Port-Breakouts for even 8x 50GBit SFP channels, what allows to create very compact and highly effective IT infrastructures within Data Centers.

CONCLUSION

With MTP®-16 fibres PreCONNECT® SEDECIM solution we can support all the available standards. 

For future proof and effective Data Centers, the IT cabling infrastructure need to be able to connect all these various Transceivers in a very flexible and scalable way including the options for various Port-Breakout configurations.
Everything starts with the decision for the Trunk Cables which are installed between the racks. Having the different Transceiver options in mind, Trunk Cables need to enable Duplex (2-fiber) as well as parallel optical transmissions on 8 or even 16 fibers. Up to distances of 100 meters, OM4 Multimode is the most effective option. Singlemode is the choice for bigger distances > 100m.

The Rosenberger-OSI PreCONNECT® OCTO and SEDECIM cabling systems support these requirements in an ideal way. Especially SEDECIM with its MTP®-16 APC Multimode connectivity is addressing the advanced performance needs for very low noise transmission channels by PAM4 coded Ethernet applications. Moreover, new VSFF (Very Small Form Factor) duplex connectors (as example MDC – see one of my former e-mails) are approaching the market which will be also supported by next generation transceivers. Both “OCTO” and “SEDECIM” are already available with VSFF (MDC) connectivity.

 

Hope we could rise your interest, and open new ideas for DataCenter design.

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