As we all know, the standard specifies MPO as a connector to the 40GBASE-SR4 QSFP+ transceiver. To connect a QSFP+ to QSFP+, we usually use a MTP 12-fiber trunk cable. In the 40GBASE-SR transmission, there are eight fibers associated with the channel—four fibers for the TX signal and four fibers for the RX signal. Therefore only 8 of the 12 fibers are used, where the remaining four are not used, and can optionally be not present in the cable. So we can also choose a MTP 8-fiber trunk cable for connectivity. Besides this, there are a number of other factors also needed to be considered when to choose a right MTP trunk cable for 40GBASE-SR4 QSFP+ connectivity. This article explains 40GBASE-SR4 QSFP+ to 40GBASE-SR4 QSFP+ cabling selections.

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Fiberstore (FS.COM) | 40GBASE-SR4 QSFP+ Transceiver Interconnection Cabling
As we all know, the standard specifies MPO as a connector to the 40GBASE-SR4 QSFP+ transceiver.
To connect a QSFP+ to QSFP+, we usually use a MTP 12-fiber trunk cable. In the 40GBASE-SR
transmission, there are eight fibers associated with the channel—four fibers for the TX signal and
four fibers for the RX signal. Therefore only 8 of the 12 fibers are used, where the remaining four
are not used, and can optionally be not present in the cable. So we can also choose a MTP 8-fiber
trunk cable for connectivity. Besides this, there are a number of other factors also needed to be
considered when to choose a right MTP trunk cable for 40GBASE-SR4 QSFP+ connectivity. This
article explains 40GBASE-SR4 QSFP+ to 40GBASE-SR4 QSFP+ cabling selections.
Use Single-mode or Multimode MTP Trunk Cable?
In the market, both single-mode and multiode MTP trunk cable are available. Which one should I
use? According to 40GBASE-SR4 standards, 40GBASE-SR4 QSFP+ transceiver supports link lengths of
100 meters and 150 meters, respectively, on laser-optimized OM3 and OM4 multimode fibers.
Therefore, to connect a 40GBASE-SR4 QSFP+ to 40GBASE-SR4 QSFP+, we should choose OM3 or
OM4 multimode MTP trunk cables. If you want to achieve a relatively longer transmission distance,
OM4 MTP Trunk cable is more suitable for you.
40GBASE-SR4 QSFP+
Transceiver
Interconnection Cabling

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MTP Trunk Cable Polarity Selection: A, B or C?
In terms of MTP trunk cable, there are three kinds of polarity options (A, B and C). Which one to
choose? In fact, according to the IEEE 40GBASE-SR4 specifications, we must select a type B MTP
8-fiber or MTP 12-fiber trunk cable. The picture below shows the working principle of type B MTP
12-fiber trunk cable. The type B trunk cable has opposing connectors with both keys oriented facing
up, however the fiber positions are reversed at each end i.e. the fiber at position 1 at one end is
connected to position 12 in the connector at the opposing end.
Choose Male or Female MTP Trunk Cable?
In terms of a MPO connector, it is divided into male and female types. They ensure that the adapter
holds the connector with the correct ends aligned with each other. A MPO trunk cable usually has
two MPO connector on each side. Therefore, MTP trunk cables are available in male–male and
female–female two versions. According to IEEE standards, MPO optics in a 40GBASE-SR4 transceiver
are always male connectors, and therefore will always accept female MPO connectors. So if we
want to connect a 40GBASE-SR4 QSFP+ to a 40GBASE-SR4 QSFP+ successfully, we must choose a
female–female MTP trunk cable.

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40GBASE-SR4 QSFP+ Transceiver Interconnection MTP Trunk Cabling Solutions
40GBASE-SR4 QSFP+ Transceiver
Part Number Image Description
QSFP-40G-SR4
Cisco QSFP-40G-SR4 Compatible
40GBASE-SR4 QSFP+ Transceiver
(MMF, 850nm, 150m, MTP/MPO,
DOM)
QFX-QSFP-40G-SR4
Juniper QFX-QSFP-40G-SR4
Compatible 40GBASE-SR4 QSFP+
Transceiver (MMF, 850nm,
150m, MTP/MPO, DOM)
JG325B
HP JG325B Compatible
40GBASE-SR4 QSFP+ Transceiver
(MMF, 850nm, 150m, MPO,
DOM)
40GBASE-SR4 QSFP+ to 40GBASE-SR4 QSFP+ MTP Trunk Cables

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Part Number Image Description
FS8OM3-2MTP-x
OM3 Type B Female–Female
MTP8 to MTP8 Trunk Cable
FS8OM4-2MTP-x
OM4 Type B Female–Female
MTP8 to MTP8 Trunk Cable
FS12OM3-2MTP-x
OM3 Type B Female–Female
MTP12 to MTP12 Trunk Cable
FS12OM4-2MTP-x
OM4 Type B Female–Female
MTP12 to MTP12 Trunk Cable
Conclusion
In summary, if we want to complete a connection between two 40GBASE-SR4 QSFP+ transceivers,
we can choose MTP 8-fiber or MTP 12-fiber trunk cables. Cable must be either OM3 or OM4 type.
Besides, only a type B female – female MTP trunk cable can satisfy your needs. Fiberstore provides
wide brand compatible 40GBASE-SR4 QSFP+ transceivers and all kinds of MTP trunk cables. Each
fiber optic transceiver has been tested to ensure its compatibility and interoperability. Please rest
assured to buy. For more information or quotation, please contact us via sales@fs.com.

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Contact Us
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Technology Park, No.6, Keyuan Road,
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Tel: +86 (755) 8300 3611
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Email: sales@fs.com
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Notice: This document is for informational purposes only and does not set forth any warranty, expressed or
implied, concerning any equipment, equipment features, or service offered or to be offered by Fiberstore.
Fiberstore reserves the right to make changes to this document at any time, without notice, and assumes no
responsibility for its use. This information document describes features that may not be currently available.
Contact a Fiberstore sales team for information on feature and product availability.
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