A Guide to 400G Transceiver Name and Specs
Confused by the name of 400G optics?
The names I usually use for communication are vendor-specific dialects. It's a common story that different interpretations are commonplace next door.
400G LR4 / 400G LR4-10 / 400G LR4-6
The 400G LR4-10 specified by MSA has a specification of 10km, but it is usually called 400G LR4. It is specified in the 100G Lambda MSA (https://100glambda.com/).
On the other hand, in IEEE, it is specified as 400G LR4-6 and 400GBASE-LR4 which is 6km.
400G DR4 + / 4x100G FR
400G DR4 with 400G 500m transmission 4 parallel in SMF is specified by IEEE802.3bs. This 2km extension specification is not as of June 2021 by the IEEE, but it is called 400G DR4 + or 4x 100G FR. It is a vendor's original name without specifications as MSA.
Since the 40G era, some data centers have been wiring in SMF parallel on a large scale. As they hope that SMF parallel transceivers would be cheaper in sooner. In that case, it will be used as DR4 / DR4 +, but most customers will use it for breakout connection with 100G compatible devices, so the notation of 4x100G FR may be kinder.
100G ER4 lite / 100G ER4L / 100G 4WDM-40
40km specification should be with FEC.
With the introduction of full-spec ER4 compatible products in the QFP28 package from around 2020, it is necessary to be more careful than before.
100G 4WDM-10 / 100G eCWDM4
The 100G 4WDM-10 has clear specifications as an MSA, but the extend CWDM4 seems to be more familiar in the market.
25G BiDi 20km, 40km IEEE wavelength
Note that the products on the market before the IEEE specification have different wavelengths from those specified by the IEEE 802.3cp.