Overview
The 100G BiDi QSFP28 (Quad Small Form-factor Pluggable 28 Bi-Directional) transceiver is an innovative solution designed for short-reach 100 Gigabit Ethernet links, specifically enabling network upgrades over existing multi-mode fiber (MMF) infrastructure. Its most significant advantage is the ability to transmit and receive 100G traffic over a standard duplex multi-mode fiber cable with LC connectors, the same cabling used for legacy 10GBASE-SR connections.
Unlike standard 100GBASE-SR4 modules that require 8 fibers and a new MTP/MPO connector, the BiDi transceiver uses advanced optics. It employs two different wavelengths (e.g., 850nm and 900nm) on each fiber strand, one for transmitting and one for receiving. Each wavelength carries a 50Gbps signal using PAM4 modulation. This bi-directional communication on both fibers allows the module to achieve a full 100Gbps aggregate data rate, providing a direct and cost-effective upgrade path for data centers and enterprise networks.
Key Features & Advantages
- Seamless 100G Upgrade: Allows migration from 10G/40G to 100G without replacing the existing duplex MMF fiber plant.
- Standard Duplex LC Connector: Eliminates the need for costly and complex MTP/MPO cabling and cassettes.
- Massive Cost Savings: Avoids the significant expense and labor associated with a full-scale fiber infrastructure overhaul.
- PAM4 Modulation: Utilizes advanced Pulse Amplitude Modulation (PAM4) to achieve a 50Gbps data rate per wavelength.
- MSA Compliant: Based on a widely adopted Multi-Source Agreement (MSA), ensuring interoperability.
- Ideal for Data Center Racking: Perfect for Top-of-Rack (ToR) to End-of-Row (EoR) or leaf-to-spine connections where duplex MMF is already in place.
The Upgrade Advantage: 100G BiDi vs. 100GBASE-SR4
When upgrading from a 10GBASE-SR network, the choice of 100G optic has major implications:
- Path with 100GBASE-SR4: This route requires a complete forklift upgrade of your fiber infrastructure. You must replace all duplex LC patch cords and trunks with new 8-fiber MTP/MPO cables. This is expensive, disruptive, and time-consuming.
- Path with 100G BiDi: This route is simple and efficient. You keep your existing duplex LC-terminated MMF cabling. The only change required is to replace the 10G SFP+ modules at each end with 100G BiDi QSFP28 modules. The savings in materials, labor, and network downtime are substantial.
Applications
100G BiDi QSFP28 is primarily used in scenarios where a cost-effective, high-speed upgrade is needed over an installed base of duplex MMF:
- Data Center Upgrades: Connecting servers and switches in racks where 10GBASE-SR was previously used.
- Enterprise Network Core: Upgrading links between distribution switches and core routers in campus wiring closets.
- High-Performance Computing (HPC): Providing faster connectivity for computing clusters without re-cabling.
Specifications
| Parameter | Value |
|---|---|
| Form Factor | QSFP28 |
| Data Rate | 103.1 Gbps |
| Wavelengths | Bi-directional 850nm / 900nm (approx.) |
| Maximum Reach | 70m on OM3 MMF / 100m on OM4 MMF / 150m on OM5 MMF |
| Fiber Type | Multi-Mode Fiber (MMF) |
| Connector Type | Duplex LC |
| Compliance | QSFP28 MSA, 100G BiDi MSA |
FAQ (Technical & product category Questions)
1. What does BiDi (Bi-Directional) mean for this module?
Bi-Directional means that each fiber in the duplex pair carries traffic in both directions simultaneously. This is achieved by using two different wavelengths of light on the same fiber strand, one for sending data and one for receiving data.
2. What is the main advantage of 100G BiDi over 100GBASE-SR4?
The main advantage is cabling cost and simplicity. 100G BiDi reuses the standard duplex LC MMF cables from legacy 10G networks, while 100GBASE-SR4 requires a brand new, more complex, and expensive 8-fiber MTP/MPO cabling infrastructure.
3. What cable do I need to connect two 100G BiDi modules?
You need a standard multi-mode fiber patch cord (OM3, OM4, or OM5) terminated with Duplex LC connectors on both ends.
4. Can a 100G BiDi module communicate with a 100GBASE-SR4 module?
No. They are fundamentally incompatible. They use different technologies, different fiber counts, and different physical connectors (LC vs. MPO).
5. Is 100G BiDi an official IEEE standard?
No, it is not an official IEEE standard like “100GBASE-SR4”. It is based on a Multi-Source Agreement (MSA) developed and agreed upon by a group of industry manufacturers to ensure interoperability and provide a standardized solution to the market.
6. What is PAM4 modulation and why is it important for 100G BiDi?
PAM4 (Pulse Amplitude Modulation with 4 levels) is a signaling technology that allows two bits of data to be transmitted per symbol, effectively doubling the data rate for a given baud rate. It’s crucial for 100G BiDi as it enables each wavelength to carry a 50Gbps data stream, which is necessary to achieve the 100Gbps aggregate speed.