When a fabric moves from 10G to 40G, the smart move is parallel optics that ride the multimode fiber you already own, and the Arista QSFP-40G-SR4 is exactly that move. This quad-lane transceiver carries 40GbE over four 850nm lanes through a single QSFP+ module, reaching 100 meters on OM3 fiber and 150 meters on OM4, which covers nearly every intra-building link a data center actually has. It is hot-pluggable, MSA-compliant, self-reporting through digital diagnostics, and coded for native recognition in Arista switches, so a 40G upgrade becomes a plug-and-go event instead of a project.
Key Features
- 40GBASE-SR4 operation at full 40GbE line rate
- Four parallel 10G lanes over 850nm VCSEL optics
- 100m reach on OM3 and 150m on OM4 multimode fiber
- Hot-pluggable, MSA-compliant QSFP+ form factor
- Digital diagnostic monitoring of optical health
- Arista-validated coding for seamless switch recognition
Product Specifications
- Form Factor: MSA-compliant QSFP+, hot-pluggable
- Data Rate: 40GbE (4 x 10Gbps parallel lanes)
- Standard: IEEE 40GBASE-SR4
- Wavelength: 850nm
- Fiber Type: multimode, OM3 up to 100m and OM4 up to 150m
- Connector: MPO-12 ribbon fiber interface
- Monitoring: digital diagnostics (DDM/DOM)
- Compatibility: Arista switches with QSFP+ ports
Use Cases
Light up spine-and-leaf 40G uplinks across a data hall, connect storage arrays to their switching tier without touching the fiber plant, or break one 40G port out into four 10G links with the appropriate breakout cable. It is also the standard module for refreshing a growing 10G fabric that has outgrown its uplink bandwidth while staying inside a multimode budget.
Compatibility
The module follows the IEEE 40GBASE-SR4 standard and QSFP+ MSA, and it is coded for Arista switches equipped with QSFP+ ports. It pairs with OM3 and OM4 multimode trunk cabling terminated in MPO-12 connectors, and supports 40G-to-4x10G breakout connections where switch-side breakout cables are used.
Frequently Asked Questions
- How far can it transmit?
- Up to 100 meters over OM3 multimode fiber and up to 150 meters over OM4, using an MPO-12 ribbon connection.
- Can I split it into four 10G links?
- Yes, with a QSFP+ to 4xSFP+ breakout cable, each 10G lane can be presented to separate 10G ports.
- Do I need OM4 fiber?
- Not necessarily. OM3 covers 100m links, which suits most intra-data-center runs, while OM4 extends reach to 150m for longer paths.
- Will it work in other vendors' switches?
- It is MSA-compliant and coded for Arista; other platforms may accept it depending on their third-party optics policies.
Fabric upgrades go smoothly when the optics are as boring as this one: standards-based, hot-pluggable, self-monitoring and already coded for the switches it will live in. For any 40G build riding existing multimode strands, the QSFP-40G-SR4 remains the quiet default that just works, link after link.
