What Is SFP Cage Keying?_
The keying consists of slots, tabs, or ridges molded into the cage body that align only with matching cutouts on the transceiver housing. This mechanical interlock stops modules with different electrical pinouts, signaling rates, or optical characteristics from seating fully. It operates independently of any electrical or firmware checks performed after insertion.
Technical Details
Keying patterns differ between SFP, SFP+, and SFP28 cages to reflect changes in supported data rates and protocol support. The cage itself mounts to the host board and provides both the mechanical guide and EMI containment around the module. Insertion requires straight push alignment; no torque is applied to the connector. Once seated, the module's latching mechanism engages separately from the keying features.
How Leviathan Systems Works with SFP Cage Keying
Field crews verify that scale-out InfiniBand or Ethernet ports on GPU racks receive correctly keyed SFP or QSFP cages before fiber or DAC attachment during commissioning. Mismatched keying is caught during visual inspection of port assemblies prior to link-up testing.
Related service
Network Testing & Commissioning →