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Complete Connect / M400 / Connect one 100GbE QSFP28 to Two 50GbE QSFP28 Transceivers
MTP 100G to 50G conversion cable

Connect one 100GbE QSFP28 to Two 50GbE QSFP28 Transceivers

100GbE ports are becoming more common within data centre networks. Whereas early 100G ports required CFP transceivers, most network cards are now designed to accept a QSFP size transceiver.

These transceivers are called QSFP28 as they can transmit up to 28GbE per channel (although typically they are working at 25GbE) over both multimode and singlemode fibre.

This blog post only covers QSFP28 transceivers that transmit SR4 over multimode or PLR4 (PSM4) over singlemode.

100G transceivers that use SR10 or SR12 (and PLR10 and PLR12) use different cabling and requires different configurations. We supply cables for these transceivers within our M1000 Series. Please chat to us via the chat window for more information.

Splitting one 100G port to Multiple Ports

There are several different options when connecting QSFP28 100GbE transceivers to other ports. These include: –

100G to 100G | 100G to Two 50G | 100G to Four 25G

All these require MTP cables which are supplied by Complete Connect within our M400 Series

Talk with one of our experts…

Splitting one 100G port to Two 50G Ports

A 100G port can be connected to two 50G ports using an MTP conversion cable.

100G SR4 QSFP28 transceivers transmit over both multimode and singlemode as 4 x 25GbE channels. These channels use 8 fibre cores (4 fibre pairs) and require MTP (MPO type) connectors.

The 8 fibres connected to the 100G transceiver, which include 4 Tx signals and 4 Rx signals can be directed as pairs to up to four other transceivers.

In the case of connecting to two 50G transceivers then 4 fibres go to each 50G transceiver.

M400 Series 100G to 50G

Complete Connect’s M400 Series Multimode 100G to 50G (x2) Fibre Conversion Cable.

Polarity Management

The 4 channels from the 100G transceiver have to be directed in a specific way to the two 50G transceivers.

Our M400 Series Conversion cable ensures the correct polartity is maintained for both direct connect cables and when additional cables (such as trunk cables and patch cables) are added into the network.

100G to 50G Conversion Cable

Technical Drawing: M400 Series Multimode 100G to 50G (x2) Fibre Conversion Cable

Over Singlemode

100G PLR4 (or PSM4) QSFP28 transceivers can be directly connected over singlemode fibre in a similar way to multimode SR4 QSFP28 transceivers. The only difference is that the MTP connectors for singlemode fibre have angled endfaces (they are APC connectors not UPC).

This means that when adding additional cables (trunks and patch cables) into the channel the polarity of the network needs to be managed in a different way.


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