Cisco QSFP-100G-PSM4-S Compatible QSFP28 100GBASE-PSM4 1310nm 500m DOM MPO-12/APC SMF Optical Transceiver Module, Support 4 x 25G-LR

Overview

This module is a high-performance, parallel optics transceiver designed as a fully compatible alternative to the Cisco QSFP-100G-PSM4-S. It operates according to the 100GBASE-PSM4 (Parallel Single Mode 4) MSA standard, which utilizes four independent, parallel 25Gb/s lanes over single-mode fiber to achieve an aggregate data rate of 100Gb/s. This architecture makes it a highly versatile and cost-effective solution for short-reach applications within data centers.

With a reach of up to 500 meters and a standard MPO-12/APC connector, the PSM4 module is ideal for point-to-point 100G links or for “breakout” configurations. In breakout mode, it can connect a single 100G switch port to four separate 25G server or switch ports using a parallel-to-duplex fiber breakout cable, enabling massive port density and flexible network designs.

Key Features

• 100% compatible with Cisco switches and devices supporting the QSFP-100G-PSM4-S part number.
• Standard: Compliant with 100GBASE-PSM4 and QSFP28 MSA.
• Dual Functionality: Supports a single 100G link or four independent 25G links.
• Technology: Four parallel 25Gb/s channels using a 1310nm laser array.
• Data Rate: 103.1 Gbps (4 x 25.78 Gbps).
• Connector: Standard MPO-12/APC.
• Reach: Supports link lengths up to 500 meters on SMF (OS2).
• Built-in Digital Optical Monitoring (DOM/DDM) for comprehensive diagnostics.
• Hot-pluggable QSFP28 form factor for seamless upgrades.

Applications

The QSFP-100G-PSM4-S compatible module is optimized for:

• High-density 25G server connectivity in spine-leaf data center architectures.
• Short-reach 100G interconnects between switches, routers, and servers.
• High-performance computing (HPC) and storage area network (SAN) clusters.
• Machine-to-machine clustering and interconnects.

Specifications

Cross-Platform Compatibility

While programmed for seamless operation in Cisco equipment, this module’s adherence to 100GBASE-PSM4 MSA standards ensures it can also function flawlessly in networking hardware from other major manufacturers that support this optical specification.

FAQ (Technical & Product Questions)

1. What is 100GBASE-PSM4 and where is it primarily used?

PSM4 stands for Parallel Single Mode 4. It’s a 100G standard that uses four parallel 25G lanes over single-mode fiber, transmitted through a multi-fiber MPO connector. It is primarily used for cost-sensitive, short-distance links (up to 500m) inside data centers, where it offers a price advantage over WDM-based transceivers like LR4.

2. How is PSM4 different from 100GBASE-SR4?

Both are four-lane parallel optics standards, but the key difference is the fiber type. 100GBASE-SR4 is designed for short reach (70m-100m) over multi-mode fiber (MMF). 100GBASE-PSM4 is designed for longer reach (up to 500m) over single-mode fiber (SMF).

3. Can I use this module to connect to four 25GBASE-LR SFP28 modules?

No, this is not a recommended or specified application. While both use single-mode fiber, the optical power budget of a PSM4 lane is designed for a 500-meter reach. A standard 25GBASE-LR SFP28 module is designed for a 10-kilometer reach. Connecting them would likely result in an unstable link or receiver overload on the SFP28 side due to the mismatched power levels and link budgets.

4. Why does PSM4 use an MPO connector instead of a Duplex LC?

PSM4 is a “parallel” technology, meaning it requires multiple fiber strands to operate—four for transmitting and four for receiving. The MPO-12 connector is a standard multi-fiber connector that houses all eight of these required fibers (plus four unused) in a single, compact interface, which is necessary for this parallel transmission method.

5. What does the “-S” suffix in QSFP-100G-PSM4-S mean?

In Cisco’s part numbering, the “-S” suffix typically denotes an “S-Class” optic. S-Class modules are optimized for standard enterprise and data center applications with a commercial temperature range (0°C to 70°C). They are designed to provide a more cost-effective solution compared to non-S-Class modules, which are often built for more demanding service provider environments.