There are two form factors for the 400G access networks and data center.
- QSFP-DD (also called QSFP56-DD, stands for Quad Small Form Factor Pluggable Double Density)
- OSFP (for Octal SFP), now we will have an overview of OSFP in this article.
What is OSFP transceiver optics?
OSFP stands for Octal Small Form-factor Pluggable; the OSFP MSA develops it. The OSFP MSA group was founded by Google and is led by Arista Networks. OSFP is a new pluggable form factor that supports eight high-speed electrical lanes that will initially support 400 Gbps (8x50G or 4x100G). It is slightly broader and deeper than the QSFP-DD but still supports 32 OSFP ports per 1U front panel and 14.4 Tbps per 1U swap slot. OSFP optics is designed with improved signal integrity and thermal performance to help the next generation of 800G optics that will use eight lanes of 100Gbps (8x100G), allowing us to upgrade easily from 400G to 800G. The OSFP also offers backward compatibility with 100G QSFP optics.
400G OSFP transceiver optics types
There are eight types of 400G OSFP transceiver optics as below: OSFP SR8, OSFP DR4, OSFP XDR4, OSFP PLR4, OSFP FR4, OSFP LR4, and OSFP 2FR4; the table below summarizes the critical parameters for the different 400G OSFP transceivers.
| OSFP Product Description | Reach | Optical Connector | Wavelength | Fiber type | Optical Modulation | Industry Standard |
| 400G OSFP SR8 | 100m | MPO-16 connector | 850nm | Parallel MMF | 50G PAM4 | OSFP MSA, IEEE802.3cm |
| OSFP-400G-DR4 | 500m | MPO-12 connector | 1310nm | Parallel SMF | 100G PAM4 | OSFP MSA, IEEE 802.3bs |
| OSFP-400G-XDR4 | 2km | MPO-12connector | 1310nm | Parallel SMF | 100G PAM4 | OSFP MSA, 100G Lambda MSA |
| OSFP-400G-FR4 | 2km | LC connector | CWDM4 | SMF | 100G PAM4 | OSFP MSA, 100G Lambda MSA |
| OSFP-400G-LR4 | 10km | LC connector | CWDM4 | SMF | 100G PAM4 | OSFP MSA, 100G Lambda MSA |
| OSFP-400G-PLR4 | 10km | MPO-12 connector | 1310nm | Parallel SMF | 100G PAM4 | OSFP MSA, 100G Lambda MSA |
| OSFP-400G-2FR4 | 2km | CS Connector | CWDM4 | SMF | 50G PAM4 | OSFP MSA, IEEE 802.3bs |
| 400G OSFP DAC | 3m | OSFP to OSFP | Copper | N/A | ||
| 400G OSFP Breakout DAC | 3m | OSFP to 2x 200G QSFP56, OSFP to 4x100G QSFPs, OSFP to 8x 50G SFP56 | Copper | N/A | ||
| 400G OSFP AOC | 100m | OSFP to OSFP | 850nm | Parallel MMF | 50G PAM4 | |
| 400G Breakout AOC | 100m | OSFP to 2x 200G QSFP56, OSFP to 4x100G QSFPs, OSFP to 8x 50G SFP56 | 850nm | Parallel MMF |
OSFP vs. QSFP-DD, What is the difference?
- MSA: The OSFP is defined by the OSFP MSA group, while the QSFP-DD MSA alliance defines QSFP56-DD
- Power consumption: OSFP allows higher power consumption of 12~15W, while the QSFP-DD allows lower power consumption of 7~12W.
- Back compatibility: The QSFP-DD is more flexible than OSFP in backward compatibility. Since QSFP-DD with an identical dimension to the QSFP, the QSFP-DD is backward compatible with 40G QSFP+, 100G QSFP28, and 200G QSFP56. While the OSFP transceiver module can not be plugged into the QSFP-DD port, but need additional hardware – a passive OSFP-QSFP adapter.
- OSFP integrates thermal management directly into the form factor, while QSFP-DD does not.
- QSFP-DD and OSFP are suitable for Data Center Interconnect (DCI) applications, including DAC, AOC, and optical connections.
Conclusion
400G OSFP transceiver provides a good solution for 400Gbps optical deployments in data centers and broadband access connectivity. More and more 400G OSFP transceivers are continuously introduced to the market, and mass production is gradually realized. It will meet rapidly growing customer demand for analytics, machine learning, and content delivery applications.