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.

http://4wdm-msa.org/

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.