If voltage remains out of range after reseating → check switch power health or replace the fiber optic module. Indicates the optic is operating in a high-temperature environment. Check compatibility between the optical module and switch Most switch brands have specific compatibility requirements. For network engineers, knowing how to view and interpret SFP information from the Cisco command-line interface (CLI) is essential. The Cisco Small Business Series Switches allow you to plug in a Small Form-factor Pluggable (SFP) transceiver in their optical modules to connect fiber optic cables. It is important to understand how to.