100G optical module have emerged as essential components in the fast-paced world of data centers and network communications,. With a plethora of models and standards available, ranging from various packaging to transmission types, buyers often find themselves navigating a complex landscape. This article aims to demystify the process, providing a practical guide to help you make informed decisions in this “light-speed” race.

What Is a 100G Optical Module?

A 100G optical module is a high-speed communication device designed for data centers and telecommunication networks, capable of supporting transmission rates of 100 Gbps. These modules convert electric signals into optical signals, enabling efficient data transmission over optical fibers. They are widely used in various applications, including data center interconnection, cloud computing, and high-performance computing

Advantages of 100G Optical Modules

• High Bandwidth: Capable of delivering a transmission rate of 100Gbps, they support large-scale data transfers, meeting the demands of high-speed data centers and high-density network applications.
• Low Latency: Compared to traditional cable transmission, optical fiber transmission offers significantly lower latency, ideal for latency-sensitive applications.
• High Energy Efficiency: Optical fiber transmission consumes less power than copper cable transmission over the same distance, contributing to reduced energy consumption in data centers
• Scalability: 100G optical modules support upgrades from 100Gbps to 400Gbps or even higher rates, catering to future bandwidth growth requirements.
• Higher Port Density: With compact form factors, 100G optical modules enable higher port density, optimizing space utilization in data centers.

Technical Standards of 100G Optical Modules

The key technical standards for 100G optical modules are established by the following organizations:

IEEE (Institute of Electrical and Electronics Engineers)
Standards such as IEEE 802.3ba and IEEE 802.3bm define 100G Ethernet interfaces, providing various standards for 100G optical modules, including:

• 100GBASE-SR4: For short-distance transmission.
• 100GBASE-LR4: For long-distance transmission.
• 100GBASE-ER4: For extended-range transmission.

The Optical Internetworking Forum (OIF)
The role entails promoting interoperability between optical modules and systems, with a particular focus on defining specifications for high-speed electrical and optical interfaces.

• CEI (Common Electrical Interface): Enables the support of high-speed electrical signal interfaces required for 100Gbps modules.
• The OIF-400ZR standard defines coherent transmission standards for 100G to 400G optical modules.

MSA (Multi-Source Agreement)
MSA outlines specifications for the form factor, size, interface, and electrical characteristics of 100G optical modules. Common form factors include QSFP28, CFP, CFP2, and CFP4.

ITU-T (International Telecommunication Union – Telecommunication Standardization Sector)
Standards such as ITU-T G.709 and G.652 define specifications for 100G optical module transmission and fiber compatibility in optical communications.

• G.709: Frame structure and interfaces for OTN optical modules.
• G.694: Wavelength range and spacing for WDM (Wavelength Division Multiplexing) signals.

100G Optical Modules’ Packaging Type

100G optical modules come in various form factors designed to meet the needs of different applications and devices. Below are the most common form factors:

1. CFP Series (CFP, CFP2, CFP4)

CFP Modules(C Form-factor Pluggable):

• The first-generation 100G form factor
• Size: The largest of the CFP variants, measuring 82 mm x 13.6 mm x 144.8 mm.
• Electrical Interface: Utilizes 10 x 10 Gbit/s lanes for electrical connections.
• Optical Interface: Supports both 10 x 10 Gbit/s and 4 x 25 Gbit/s optical lanes.
• Power Consumption: As the most power-hungry of the variants, it consumes less than 24 watts.
• Application: Ideal for long-distance transmission, reaching distances of up to 10 km or more, depending on the specific module.

CFP2 Modules

• Size: A compact version, half the size of the CFP module, with dimensions of 41.5 mm x 12.4 mm x 107.5 mm.
• Port Density: Designed to support higher port density compared to the original CFP.
• Electrical Interface: Offers flexibility with 4 x 25 Gbit/s, 10 x 10 Gbit/s, 8 x 25 Gbit/s, and 8 x 50 Gbit/s lanes.
• Power Consumption: More energy-efficient than CFP, consuming typically around 22W to 24W.
• Advanced Modulation: Utilizes advanced modulation formats like PM-QPSK and PM-16QAM for enhanced performance.

CFP4 Modules

• Size: The smallest among the CFP variants, measuring just 21.5 mm x 9.5 mm x 92 mm.
• Port Density: With a width that’s a quarter of the original CFP, it achieves the highest port density.
• Electrical Interface: Supports 4 x 25 Gbit/s and 4 x 10 Gbit/s interfaces for flexibility.
• Power Consumption: The most power-efficient option in the CFP family, offering low power usage.
• Efficiency: Achieves 100G transmission rates with four 25G channels, making it more efficient than the original CFP.
• Applications: Perfect for 40G/100G Ethernet applications where space and power efficiency are key

Advantages:
Ideal for long-distance transmission (10–40 km or beyond) and supports various distance requirements.

Applications:

• Telecommunications backbone networks.
• Metro networks for long-distance transmission.
• Core network equipment requiring extended-range connectivity.

2. QSFP28

• Overview:
  QSFP28 (Quad Small Form-factor Pluggable 28) is the most widely adopted 100G form factor, extensively used in data centers and enterprise networks.
• Size:
  Compact and space-efficient, enabling high-density port configurations.
• Transmission Mode:
  Supports both multimode and single-mode fiber.

Advantages:

• Low power consumption (typically under 3.5W).
• Modular and easy to manage.
• Small footprint, ideal for dense network setups.

Applications:

• Top-of-Rack (ToR) switches in data centers.
• Leaf-Spine network architecture.
• High-density switches and routers.

3. CXP

• Compact Design:
  Smaller than QSFP28, making it ideal for high-density applications.
• Multichannel Architecture:
  Features 12 channels, each with a transmission rate of 10Gbps, achieving a total rate of 120Gbps. Typically used for 100Gbps transmission, with extra channels available for redundancy or management signals.
• Transmission Distance:
  Designed for short-range, high-speed interconnects within data centers. Transmission distances are typically under 100 meters using multimode fiber (e.g., OM3 or OM4).
• Applications:
  • High-performance computing clusters.
  • High-speed interconnects between racks in data centers.

How to Choose from CFP, CFP2, CFP4, QSFP28 and CXP ?

• Short-distance transmission within data centers: QSFP28, CXP
• Long-distance transmission and telecom backbone networks: CFP, CFP2, CFP4

In our next article, we’ll explore the key 100G standards—100GBASE-SR4, DR1, DR4, BiDi SR, LR4, CWDM4, SWDM4, ER, and ZR—and how they differ in distance, fiber type, and encoding. From short-range data center links to ultra-long-haul networks, we’ll break down their features, applications, and practical selection tips. Say goodbye to confusion and hello to clarity—your ultimate guide to 100G modules is just around the corner. Stay tuned! 100G Optical Module: How to Choose Between SR4,DR4, FR4, LR4, CWDM4, SWDM4, ER4 and ZR4?

Question: Does Asterfusion offer 100G switches?

Asterfusion offers multiple models of 100G switches, all pre-installed with our self-developed enterprise SONiC distribution. These switches are suitable for various scenarios, such as campus networks and data centers. For more details, please refer to the following articles:

• 100G Data Center Switches: Driving the Future through Open Networking
• Asterfusion enterprise SONiC based 25G/10G open network switch overview