Maximum Transmission Reach
Maximum SFP reach is the longest link distance an optical module supports under its specified conditions.
The distance is tied to a particular fibre type, data rate and optical link arrangement. It is not a universal rating for every cable that fits the connector.
Maximum Transmission Reach — SFP Ethernet Cable
For an SFP Ethernet link, the supported reach helps match the module to the required cable run. The receiving module, connector losses and fibre characteristics also need to remain within the permitted optical conditions.
Compare reach under the same fibre and speed conditions, and account for the complete link rather than only cable length. A longer-reach module is not automatically suitable for every short connection: the receiving optical level must also be appropriate. Keep module reach separate from the physical length of a supplied patch cable.