Comprehensive Guide to 100G BIDI QSFP28 Simplex LC SMF Transceivers

The demand for high-speed, cost-effective, and fiber-efficient optical transceivers has surged with the growth of data centers, telecommunications, and 5G networks. The 100G BIDI QSFP28 (Bidirectional Quad Small Form-Factor Pluggable 28) transceiver is a standout solution, enabling 100 Gigabit Ethernet (100GbE) over a single-mode fiber (SMF) with a simplex LC connector. By using bidirectional transmission, it reduces fiber usage by 50% compared to traditional duplex systems.

What is a 100G BIDI QSFP28 Transceiver?

The 100G BIDI QSFP28 is a high-performance optical transceiver designed for 100 Gigabit Ethernet (100GbE) applications. Unlike traditional transceivers that require two fibers (one for transmitting and one for receiving), the 100G BIDI QSFP28 uses bidirectional technology to transmit and receive data over a single SMF strand using different wavelengths. This is achieved through Wavelength Division Multiplexing (WDM), typically operating at wavelengths such as 1271nm/1331nm, 1291nm/1311nm, or 1304nm/1309nm, depending on the module and distance requirements. The use of a simplex LC connector makes the 100G BIDI QSFP28 highly efficient, as it reduces fiber infrastructure costs by up to 50% compared to duplex LC systems. This is particularly valuable in environments with limited fiber resources, such as data centers, metro networks, and 5G fronthaul applications. The transceiver complies with the QSFP28 Multi-Source Agreement (MSA), IEEE 802.3bm, and ITU-T standards, ensuring compatibility with major vendors like Cisco, Juniper, and Arista. It also supports digital diagnostic monitoring (DDM) for real-time performance tracking and integrates Forward Error Correction (FEC) for reliable data transmission, particularly over longer distances.

Key Features of 100G BIDI QSFP28 Transceivers

The 100G BIDI QSFP28 offers a range of features that make it ideal for high-speed, long-distance applications:

Bidirectional Transmission: Utilizes a single SMF strand for both upstream and downstream data, doubling fiber capacity.

Simplex LC Connector: Simplifies cabling and reduces infrastructure costs.

High Data Rate: Supports 100Gbps Ethernet with line rates of 103.125Gbps (or 111.81Gbps for OTU4 in some modules).

Multiple Reach Options: Available for distances of 10km, 20km, 30km, 40km, 70km, and 80km, catering to various network requirements.

Low Power Consumption: Typically consumes less than 4.5W–6.5W, depending on the model and distance.

Forward Error Correction (FEC): Many modules, especially for longer reaches, require FEC (e.g., KR4 or RS (544,514)) to ensure signal integrity.

Wavelength Flexibility: Operates on specific wavelength pairs (e.g., 1271nm/1331nm for 10km, 1304nm/1309nm for 40km) to support bidirectional communication.

Wide Compatibility: Compliant with IEEE 802.3bm, ITU-T G.959.1, and QSFP28 MSA standards, ensuring interoperability with major vendors like Cisco, Juniper, and Arista.

Forward Error Correction (FEC) in 100G BIDI QSFP28

Forward Error Correction (FEC) is a critical feature in high-speed optical transceivers like the 100G BIDI QSFP28, as it corrects bit errors caused by signal degradation over long distances or in noisy environments. FEC adds redundant data to the transmitted signal, allowing the receiver to detect and correct errors without retransmission. In 100G BIDI QSFP28 modules, FEC requirements vary by transmission distance due to differences in optical budget, signal-to-noise ratio, and modulation formats (e.g., NRZ for shorter reaches, PAM4 for longer reaches). Below, we detail FEC requirements for each distance.

The following table summarizes FEC requirements and recommendations for 100G BIDI QSFP28 transceivers across different distances:

Distance	Module Type	FEC Requirement	Recommendation
10km	PAM4	Not mandatory, recommended	Enable RS-FEC for enhanced stability, especially in complex fiber environments.
20km	PAM4	Recommended, mandatory for PAM4	Enable RS-FEC to ensure performance, particularly with PAM4 modulation.
30km	PAM4	Typically required, mandatory for PAM4	Enable RS-FEC to maintain signal integrity.
40km	PAM4	Mandatory	Enable RS-FEC for reliable 40km transmission.
70km	LWDM4	Mandatory	Enable RS-FEC to support ultra-long-haul links.
80km	LWDM4	Mandatory	Enable RS-FEC to ensure error-free transmission.

FEC Recommendations and Best Practices

Short Distances (10km, 20km): Prioritize enabling FEC to ensure stability, especially for PAM4 modules or in environments with high dispersion or noise. RS-FEC enhances link reliability without significant overhead.

Medium to Long Distances (30km and above): FEC is mandatory due to increased signal degradation. Switches must support RS-FEC to achieve the specified reach.

Compatibility Verification: Check the module’s data sheet (FiberMall) and switch firmware to confirm support for required FEC and modulation formats (NRZ or PAM4).

Deployment Testing: Use optical power meters and DDM data to verify link performance and assess FEC effectiveness in real-world conditions.

Transmission Distances and Applications

The 100G BIDI QSFP28 is available in multiple variants to support different transmission distances, each tailored to specific use cases. Below, we explore the specifications and applications for each distance:

1. 10km: 100G BIDI QSFP28 10km

Wavelengths: Typically 1271nm/1331nm.

Optical Budget: Approximately 6–8 dB.

FEC Requirement: Optional, depending on the host platform.

Applications: Ideal for short-reach data center interconnects, enterprise networks, and campus backbones. The 10km 100G BIDI QSFP28 is perfect for environments where fiber resources are limited but high-speed connectivity is essential.

• 20km: 100G BIDI QSFP28

Wavelengths: Commonly 1291nm/1311nm or 1280nm/1310nm.

Optical Budget: Around 10–12 dB.

FEC Requirement: Typically requires RS FEC for stable performance.

Applications: Suited for metro networks, 5G fronthaul, and regional data center interconnects. The 20km 100G BIDI QSFP28 supports longer intra-city links while maintaining cost efficiency.

• 30km: 100G BIDI QSFP28

Wavelengths: Often 1304nm/1309nm.

Optical Budget: Approximately 13–14.7 dB (OMA).

FEC Requirement: Requires RS (544,514) FEC for full reach; without FEC, the distance may be limited.

Applications: Used in long-haul data center interconnects, enterprise networks, and telecom applications. The 30km 100G BIDI QSFP28 is designed for scenarios requiring robust performance over extended distances.

• 40km: 100G BIDI QSFP28 40km

Wavelengths: Typically 1304.58nm/1309.14nm.

Optical Budget: Around 17.6–18.5 dB.

FEC Requirement: Requires KR4 or RS FEC for full 40km reach; without FEC, the reach is approximately 30km.

Applications: Ideal for long-reach metro networks, regional data centers, and high-capacity enterprise backbones. The 40km 100G BIDI QSFP28 is a cost-effective solution for extended single-fiber connectivity.

• 70km: 100G BIDI QSFP28 70km

Wavelengths: Typically 1295.56nm/1300.05nm or 1304.58nm/1309.14nm.

Optical Budget: Approximately 20–24 dB.

FEC Requirement: Requires KR4 FEC for stable performance.

Applications: Designed for ultra-long-haul applications, such as regional telecom networks and inter-data center connectivity. The 70km 100G BIDI QSFP28 supports high-capacity links in fiber-scarce environments.

• 80km: 100G BIDI QSFP28 80km

Wavelengths: Often 1273nm/1310nm or 1295.56nm/1309.14nm.

Optical Budget: Up to 24 dB.

FEC Requirement: Requires KR4 FEC for full reach; some modules use SOA+PIN receivers for enhanced sensitivity.

Applications: Suited for long-haul telecom networks, hyperscale data centers, and service provider backbones. The 80km 100G BIDI QSFP28 is the ultimate solution for maximizing fiber efficiency over vast distances.

Technical Insights: How 100G BIDI QSFP28 Works

The 100G BIDI QSFP28 leverages advanced optical technologies to achieve bidirectional transmission. Here’s a breakdown of its working principles:

WDM Technology: The transceiver uses WDM to transmit and receive signals on different wavelengths over a single fiber. For example, a 10km module might transmit at 1271nm and receive at 1331nm, while a 40km module uses 1304.58nm/1309.14nm.

PAM4 vs. NRZ Modulation: For longer distances (e.g., 30km and above), many 100G BIDI QSFP28 modules use PAM4 (Pulse Amplitude Modulation 4-level) to achieve higher data rates within a single optical channel. Shorter distances (10km, 20km) may use NRZ (Non-Return-to-Zero) for compatibility with legacy switches.

EML and PIN Receivers: High-performance Electro-absorption Modulated Lasers (EML) are used for transmission, while PIN photodiodes or SOA+PIN receivers ensure high sensitivity for long-distance applications.

FEC Integration: Forward Error Correction (FEC) is critical for longer reaches (30km–80km) to correct signal errors and ensure reliable data transmission.

Benefits of 100G BIDI QSFP28 Transceivers

The 100G QSFP28 BIDI offers significant advantages for modern networks:

Fiber Efficiency: By using a single fiber for bidirectional communication, it reduces cabling costs and maximizes existing infrastructure.

Cost Savings: Eliminates the need for additional fiber strands, lowering deployment and maintenance expenses.

Scalability: Supports high-density deployments in data centers and telecom networks, allowing operators to scale bandwidth without extensive infrastructure upgrades.

Versatility: Available for multiple distances (10km to 80km), making it suitable for diverse applications from short-reach data centers to long-haul telecom.

Interoperability: Compatible with major vendors’ equipment, ensuring seamless integration into existing networks.

Energy Efficiency: Low power consumption (typically <5W for shorter reaches, <6.5W for 80km) supports green data center initiatives.

Applications of 100G BIDI QSFP28 Transceivers

The 100G QSFP28 BIDI is deployed across various industries and scenarios:

Data Centers: Facilitates high-speed interconnects between servers, switches, and routers, especially in hyperscale environments with limited fiber availability.

Metro Networks: Supports intra-city connectivity for enterprises and service providers, offering cost-effective solutions for 20km–40km links.

5G Fronthaul: Meets the high-bandwidth, low-latency requirements of 5G networks, particularly for 10km–30km fronthaul links.

Telecom Networks: Enables long-haul connectivity (70km–80km) for regional and national backbone networks.

Enterprise Networks: Provides high-capacity links for campus and corporate networks, supporting digital transformation initiatives.

Conclusion

The 100G BIDI QSFP28 Simplex LC SMF transceiver is a revolutionary solution for high-speed, fiber-efficient networking. Supporting distances from 10km to 80km, it caters to data centers, metro networks, 5G fronthaul, and long-haul telecom. FEC requirements range from optional (10km) to mandatory (30km–80km), ensuring reliable performance. By leveraging bidirectional WDM, the 100G BIDI QSFP28 optimizes fiber usage, reduces costs, and supports scalable networks.