Understanding 400G Ethernet Optical Transceivers for Data Center Operators

As data center networks demand more bandwidth, 400G Ethernet is becoming the new standard. For data center operators new to 400G hardware, understanding optical transceiver standards is crucial for effective implementation. Here’s a rundown of the key types and specifications.

1. Types of 400G Ethernet Optical Transceivers

1.1 QSFP-DD (Quad Small Form-Factor Pluggable Double Density)

Description: QSFP-DD is an enhanced version of the QSFP form factor that doubles the density by adding an extra row of electrical contacts.

Connector Type: Typically uses MPO-12 or LC connectors for fiber optics.

Reach: Up to 500 meters (e.g., 400GBASE-DR4) with single-mode fiber and up to 100 meters (e.g., 400GBASE-SR8) with multimode fiber.

Cabling: Requires new cabling for longer distances (single-mode fiber), but can use existing multimode fiber for shorter reaches.

Usage: Ideal for high-density data center applications due to its compact size.

1.2 OSFP (Octal Small Form-Factor Pluggable)

Description: Designed specifically for 400G speeds, OSFP is slightly larger than QSFP-DD, allowing better thermal management.

Connector Type: Uses MPO-16 connectors for parallel optics.

Reach: Up to 10 kilometers (e.g., 400GBASE-LR8) using single-mode fiber.

Cabling: New cabling is required for longer distances.

Usage: Suited for data centers needing longer reach and higher thermal efficiency.

1.3 CFP8 (C Form-Factor Pluggable)

Description: Part of the CFP family designed for high-power and long-distance 400G transmission.

Connector Type: Utilizes LC or MPO connectors.

Reach: Can reach up to 10 kilometers (e.g., 400GBASE-LR8) using single-mode fiber.

Cabling: Typically requires single-mode fiber for long-distance transmission.

Usage: Often used in scenarios requiring extended reach, such as between data centers.

1.4 COBO (Consortium for On-Board Optics)

Description: Not a plug-in module but rather an integrated, onboard optical module that provides high-density optical connections directly on the circuit board.

Connector Type: Depends on the specific application; usually uses MPO or LC connectors for fiber connections.

Reach: Can vary, supporting distances up to 10 kilometers or more.

Cabling: Similar requirements to other transceivers, focusing on high-density applications.

Usage: Best for large-scale data centers where space efficiency and high-speed connections are crucial.

2. Cabling Considerations for 400G

Multimode Fiber: For shorter reaches (up to 100 meters), existing OM3, OM4, or OM5 multimode fiber can often be reused, particularly with standards like 400GBASE-SR8.

Single-mode Fiber: For longer distances (500 meters to 10 kilometers), single-mode fiber is required. Upgrading to single-mode fiber may involve additional costs, but it provides future-proofing for data center networks.

Connector Types: Most 400G transceivers use MPO/MTP connectors (e.g., MPO-12, MPO-16) or LC duplex connectors. Ensure that the optical infrastructure (cables and connectors) in the data center aligns with the transceiver type being deployed.

3. Choosing the Right 400G Transceiver

Distance Requirements: Choose 400GBASE-SR8 for shorter distances (100 meters), 400GBASE-DR4 for medium distances (500 meters), or 400GBASE-LR8 for long distances (up to 10 kilometers).

Thermal Management: If thermal efficiency is a concern, consider the OSFP form factor, which has enhanced heat dissipation capabilities.

Density Needs: QSFP-DD is ideal for high-density applications due to its compact size, whereas OSFP is slightly larger but offers better cooling.

Conclusion

400G Ethernet optical transceivers come in several form factors (QSFP-DD, OSFP, CFP8) to meet different distance, density, and thermal requirements. Data center operators need to consider cabling upgrades and choose the appropriate transceiver standard based on their network's specific needs. Understanding these standards helps optimize performance and future-proof data center infrastructure. Ready to make the move? Call us at +1 (415) 625-9976 or click here to connect today.