SR, LR, ER & ZR Explained

Understand reach-family labels without treating them as universal specifications.

Overview

Reach labels are useful families, but their exact distance, wavelength, connector, FEC and application depend on the Ethernet generation and product standard.

Key planning checks

SR commonly indicates short-reach optical technology.
LR and ER extend reach using single-mode approaches.
ZR can involve coherent or other long-distance implementations.
Always read the complete product specification, not only the suffix.

NRCube review note

Keep the unknowns visible

A longer-reach family is not automatically a drop-in replacement for a shorter-reach optic.