Both sides of the switch need optical modules
When connecting two network switches, both SFP ports on each switch must use the same wavelength, or similar SFP modules that are compatible with each other. Matching SFP modules with switches or media converters is a critical step in building a reliable fiber-optic network. It's just that OM4 has better optical characteristics, and as such can keep signals intact over a longer distance. The following figure shows the optical modules supported by the S5720-12TP-LI-AC.
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