New Zealand Solution Optical Switch QSFP28

QSFP28 is a 100G-capable transceiver standard widely supported by modern optical switches, enabling high-density, high-speed network connectivity.What is QSFP28?

QSFP28 (Quad Small Form-Factor Pluggable 28) is a hot-swappable transceiver designed for 100 Gigabit Ethernet (100GbE). It aggregates four parallel 25G electrical lanes, each capable of up to 28 Gbaud signaling, providing sufficient overhead for error correction and clocking protocols while delivering 100 Gbps payload capacity . The module can convert these electrical lanes into optical signals using various technologies, including SR4, LR4, CWDM4, or PSM4, depending on the fiber type and distance requirements . QSFP28 modules are backward-compatible with QSFP+ cages, allowing higher bandwidth density without redesigning switch front panels .

QSFP28-Compatible Switches

A QSFP28 switch is a networking platform that supports 100G Ethernet through QSFP28 ports. Some switches have native QSFP28 ports, while others, such as QSFP-DD or OSFP platforms, offer backward compatibility, allowing QSFP28 modules to operate without adapters . Examples include:

• Cisco Nexus 9500 series – native QSFP28 support on certain line cards
• Arista 7060X4 series – supports both QSFP28 and QSFP-DD configurations
• NVIDIA SN4700 – QSFP-DD ports that accept QSFP28 modules natively While MSA-compliant modules are theoretically interchangeable, vendor whitelists, firmware checks, and FEC requirements can affect interoperability .

Electrical and Optical Interfaces

QSFP28 uses the CAUI-4 electrical interface, with four transmit (Tx) and four receive (Rx) differential pairs connecting the host ASIC to the module . Each lane typically runs at ~25.78125 Gbps with 64b/66b encoding. The module maps these lanes to optical channels, usually over 8-fiber MPO/MTP connectors (4 Tx + 4 Rx) for multimode or single-mode fiber . Pinout considerations include GND, VccRX, VccTX, and Vcc1, which must be applied concurrently to ensure proper operation .

Deployment Considerations

When deploying QSFP28 in optical switches:

• Ensure module and switch compatibility, checking vendor whitelists and firmware versions .
• Select the appropriate optical variant (SR4, LR4, CWDM4) based on distance and fiber type .
• Consider breakout configurations, as a single QSFP28 port can be split into four 25G connections for flexible network design .
• Verify power budgets and thermal management, as QSFP28 modules consume more power than QSFP+ modules . QSFP28 remains the dominant choice for spine-leaf data centers, cloud infrastructure, and high-performance computing networks, offering a balance of throughput, power efficiency, and deployment flexibility . For New Zealand-based deployments, ensure that local vendors or distributors provide MSA-compliant QSFP28 modules compatible with your switch platform, and confirm support for any site-specific configurations or FEC requirements.