"SFP transceiver" is industry shorthand for the whole pluggable idea, but this page stays with the founding generation: the gigabit small-form module itself. An SFP module is a hot-swappable unit carrying a laser transmitter, a photodiode receiver, driver and recovery electronics, and a duplex (or single, for BiDi) optical interface in a standard metal shell. The host — a switch or a network card — provides power, the high-speed electrical interface and the cage; the module provides the physics of the link. The faster generations have their own pages — SFP+ at 10G, SFP28 at 25G and QSFP28 at 100G — because their selection questions differ from the gigabit class covered here.
That division of labour is what makes the format so durable. The same server adapter can leave the factory as a multimode in-rack card and become a single-mode campus card by swapping a module that costs a fraction of the NIC. Within the gigabit generation, the GRT range divides by fiber discipline — single-mode, multimode, copper and BiDi, the variants catalogued on the SFP modules page — and the choice between them is made by the plant the module will live in, not by the cage, which is common to all of them.
How the family divides
- By fiber: single-mode (1310/1550 nm) or multimode
- By direction: duplex pairs, or BiDi on a single strand
- By presentation: optical, or copper over RJ45
- By reach: in-rack metres to campus kilometres
For selection, start from the fiber you already own: its type and length dictate the module, and the module dictates what the cage must be. The blog guide on transceiver compatibility covers coding, brand matching and testing in depth.
Are transceivers hot-swappable?
Yes, the family is designed for hot insertion and removal, so links can be reconfigured without powering down the host.
What does "coding" mean?
The module carries a small memory with identity and capability data that the host reads on insertion. Hosts differ in how strictly they check that data, so compatibility is a per-platform question: name your switch or NIC model with your inquiry, and prove the pairing on your own equipment with a loaner unit under our free testing service before a fleet order.