Optical modules and switches, as core network hardware, form a closely interdependent and symbiotic relationship—optical modules are the "extension arms" of switches that overcome transmission limitations, while switches are the "command center" for optical modules to function. For details about the optical modules supported by optical ports on switches, see "Appearance and Structure" of a specific switch model in the Hardware Description. You can also use the Hardware Center to query the. SFP (Small Form-factor Pluggable) is a compact, hot-pluggable network interface module used to connect network devices (switches, routers, firewalls) to fiber optic or copper cables. The connection between two or more Ethernet switches in a certain way (Uplink port, etc.