QSFP-100G-SRBD Arista 100GBASE-bidi QSFP Optical Transceiver

QSFP-100G-SRBD Optical Transceiver Overview

The QSFP-100G-SRBD transceiver, also known as the Arista 100GBASE-BiDi QSFP Optical Transceiver, is a high-performance, compact, and low-power optical module designed for 100 Gigabit Ethernet (100GbE) applications. Engineered specifically for short-range data center connectivity, it enables dual-wavelength bidirectional communication over a single pair of multimode fibers (MMF). The QSFP-100G-SRBD supports transmission distances up to 70 meters over OM3 fiber and up to 100 meters over OM4 fiber.

This optical module eliminates the need for multiple fiber pairs, reducing cable complexity and infrastructure costs while preserving valuable switch ports and rack space. Designed in accordance with MSA standards, it ensures multi-vendor interoperability across various networking equipment.

Technical Specifications and Performance

Form Factor and Interface

The QSFP-100G-SRBD is housed in the industry-standard Quad Small Form-factor Pluggable (QSFP28) footprint. It uses a duplex LC connector, offering a streamlined installation and compact interface, optimized for high-density deployments.

Wavelength and Transmission Technology

One of the unique characteristics of this module is its bidirectional (BiDi) capability. It transmits and receives simultaneously over the same fiber strand using two wavelengths: typically around 850 nm and 910 nm. This bidirectional communication is made possible through internal wavelength division multiplexing (WDM), optimizing bandwidth usage.

Supported Distances

• Up to 70 meters on OM3 multimode fiber (MMF)
• Up to 100 meters on OM4 multimode fiber (MMF)

This range makes it ideally suited for intra-data center links such as top-of-rack (ToR) to aggregation layer connectivity.

Data Rate and Encoding

The QSFP-100G-SRBD supports data rates of 100Gbps, achieved by four independent lanes operating at 25Gbps each. The module uses PAM4 or NRZ modulation depending on vendor-specific implementations but conforms to the IEEE 802.3bm and 100GBASE-SR4/BiDi specifications.

Compatibility and Use Cases

Switch and Server Compatibility

The QSFP-100G-SRBD is interoperable with a wide range of Ethernet switches, routers, and network interface cards (NICs) that support 100G QSFP28 ports. Common use cases include:

• Data center spine-leaf architectures
• High-performance computing clusters
• Cloud-scale fabric interconnects
• Enterprise core-to-aggregation switching

Arista and OEM Compatibility

Originally manufactured for Arista Networks, this transceiver can be used in any compatible OEM device that supports QSFP-100G-SRBD modules. Many third-party vendors offer 100% compatible versions that meet or exceed the original specifications.

Advantages of 100GBASE-BiDi Technology

Reduced Cabling Complexity

Traditional 100G transceivers like 100GBASE-SR4 require eight-fiber MTP/MPO cabling. In contrast, the QSFP-100G-SRBD uses only a duplex LC connector, dramatically simplifying fiber routing, especially in legacy environments where existing two-fiber cabling is present.

Lower Deployment Costs

By using existing duplex MMF infrastructure, network operators can avoid costly fiber plant upgrades. This is particularly beneficial in large-scale data centers where retrofitting hundreds or thousands of fiber links would be prohibitively expensive.

High Density and Scalability

The QSFP28 form factor allows for high port density on switches and routers, enabling more 100G ports per rack unit. When combined with BiDi optics, this density advantage multiplies, supporting more connections with fewer fibers and less rack space.

Power Efficiency

With a typical power consumption of less than 3.5W per module, the QSFP-100G-SRBD contributes to overall energy savings in the data center. It enables long-term sustainability without compromising performance or reliability.

Fiber Type and Connectivity Guidelines

Multimode Fiber Requirements

The QSFP-100G-SRBD is optimized for use with OM3 and OM4 multimode fiber. The shorter modal dispersion and lower attenuation in OM4 enable longer distances compared to OM3:

• OM3: 70 meters
• OM4: 100 meters

Connector Type

This module uses a standard duplex LC connector. Installation is simple, and the use of LC fiber patch cords is widespread, making replacements and maintenance tasks straightforward.

Installation and Handling Best Practices

ESD and Cleanliness Precautions

Optical transceivers are sensitive to static electricity and contamination. Always wear an ESD wrist strap and ensure LC connectors are clean and capped when not in use. Use proper cleaning tools to remove dust or debris before mating connectors.

Hot Swappable Support

The QSFP-100G-SRBD is a hot-swappable module, allowing technicians to insert or remove it without powering down the host device. This feature minimizes network downtime and supports real-time maintenance activities.

Firmware and Diagnostic Monitoring

Many modules include Digital Optical Monitoring (DOM) functionality, enabling real-time access to metrics like:

• Laser bias current
• Optical transmit and receive power
• Module temperature
• Supply voltage

These diagnostics help predict failures, optimize performance, and simplify troubleshooting.

Reliability and Environmental Standards

Operating Temperature Range

The QSFP-100G-SRBD supports a standard commercial operating temperature range of 0°C to 70°C. Some industrial-grade variants offer extended temperature support, suitable for more demanding environments.

MTBF and Durability

With a Mean Time Between Failures (MTBF) exceeding 1 million hours, this module is engineered for long-term operation in mission-critical networks. Robust design practices ensure resistance to mechanical stress, vibration, and EMI/RFI interference.

Market Applications and Deployment Scenarios

Hyperscale Data Centers

Large-scale cloud service providers rely on 100G connectivity to move massive volumes of data between racks and across aggregation points. The QSFP-100G-SRBD fits this environment by offering high bandwidth and fiber-saving efficiency.

Enterprise Core Switching

Enterprises modernizing their core networks benefit from the cost-effective migration path this transceiver provides. It allows 10G/40G links to be consolidated into 100G over existing LC-duplex MMF.

High-Performance Computing (HPC)

The low-latency and high-throughput demands of HPC networks are well-served by this optical module. Its BiDi functionality reduces cable clutter and enhances airflow in tightly packed compute environments.

Campus and Metro Aggregation

In campus or metro networks, where fibers may be shared between multiple buildings or facilities, the duplex LC format simplifies cable routing and conserves scarce fiber resources.

Regulatory Compliance and Certification

Industry Standards

The QSFP-100G-SRBD complies with multiple industry standards to ensure compatibility and safety:

• IEEE 802.3bm / 802.3cd
• QSFP28 MSA
• RoHS and REACH compliant
• Class 1 Laser IEC/EN 60825

Vendor Lock-In and 3rd-Party Options

While some OEMs may enforce firmware checks to discourage third-party optics, many compatible QSFP-100G-SRBD modules are available that meet all regulatory and technical requirements. These offer significant savings without sacrificing performance.