Definition of 400G QSFP-DD Transceivers
QSFP-DD stands for Quad Small Form Factor Pluggable Double Density. The 400G
QSFP-DD Transceiver follows the same port densities system as the QSFP and
QSFP28, but the QSFP-DD will support eight lanes instead of four lanes for the QSFP
and QSFP28, which double the density.
Each of the eight lanes will operate a data rate up to 50Gb/s providing a 400Gb/s
data speed and increasing the capacity of the QSFP28 by four. The 400G QSFP-DD
MSA published that the size of the optical transceivers enables to put 36 ports in one
switch slot, accumulating 14.4 Tbp/s in one slot.

Multi-mode Transceivers
Multi-mode transceivers are the low cost transceivers. QSFP-DD SR8 use more
expensive non-standard MPO connectors which cancel out some of the cost savings of
the multi-mode transceiver.
400G QSFP-DD SR8
The 400G QSFP-DD SR8 transceiver supports connections of up to 100 meters over
multi-mode fiber and uses MPO connectors. The wavelength is 850nm. It is compliant
with the QSFP-DD MSA.


Single-mode Transceivers
Single-Mode transceivers are more expensive than multi-mode transceivers but they
allow to reach longer distance.
400G QSFP-DD DR4
The 400G QSFP-DD DR4 transceiver supports connections of up to 500 meters over
single-mode fiber and uses MPO connector. The wavelengths is 1310nm. It is
compliant with the QSFP-DD MSA.
400G QSFP-DD DR4+
The 400G QSFP-DD DR4+ supports connections of up to 2 kilometers over single-
mode fiber and uses MPO connector. The wavelengths is 1310nm. It is compliant with
the QSFP-DD MSA.
400G QSFP-DD LR4
The 400G QSFP-DD LR4 transceiver supports connections of up to 10 kilometers over
single-mode fiber and uses LC connectors. The wavelengths are 1296 to 1309nm. It
is compliant with the QSFP-DD MSA.

400G QSFP-DD Loopback
The 400G QSFP-DD Loopback is a cost effective and high quality solutions to test
400G QSFP-DD transceivers ports.