HPE Aruba QSFP28 Manual page 10

Figure 1: LC connector (a simplex connector is shown)
• Multifiber Push On (MPO) connector.
Figure 2: MPO connector
The 40G QSFP+ MPO transceiver modules use only female MPO connectors, which have guide holes in the
end face of the MPO connector (the transceiver has guide pins within the MPO receptacle).
MPO connectors are classified as the following types based on the polish type:
◦ Physical contact (PC): End face polished flat.
◦ Angle-polished contact (APC): End face polished with an angle, typically 8°.
MPO connectors are available with 12 fibers or 24 fibers:
12-fiber MPO connector (40G, SR4, eSR4, and 100G SR4 transceivers use 8 of the available 12 fibers. The
four center fibers are unused. )
Figure 3: End face of a 12-fiber connector and channel assignment
MPO transceivers typically use four channels to communicate. These channels are assigned using the outer
eight fibers (the center four are unused).
Transmit channels are one set of four fibers, and the receive channels are on the other set of four fibers.
Because of this, the cables used and fiber cable connections from endpoint to endpoint effectively create a
crossover connection.
Be aware that using two crossover cables in series cancels this effect and no connection will be established.
An odd number of crossovers combined with straight-thru fiber connections will effect a crossover connection.
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40G BiDi uses only Duplex fiber versus MPO (see below) for 40G SR4 applications.
ArubaOS-Switch and ArubaOS-CX Transceiver Guide