LANs (local area networks) use fiber optics primarily in the backbone but increasingly to the desk. The LAN backbone often needs longer distance than copper cable (Cat 5/5e/6) can provide and of course, the fiber offers higher bandwidth for future expansion. Most large corporate LANs use fiber backbones with copper wire to the desktop.
The small form-factor pluggable (SFP) is a compact, hot-pluggable optical module transceiver used for both telecommunication and data communication applications. This optical device converts the serial electrical to optical signals and vice versa using a parallel designed transmitter and receiver circuits using a single PCB layout. The mechanical and electrical interface are specified by a multi-source agreement (MSA) under Small Form Factor Committee (SFF Committee (2001-05-01), INF-8074i Specification for SFP (Small Formfactor Pluggable) Transceiver). The SFF Committee is a popular industry format jointly developed and supported by many network component vendors. The Digital Diagnostics Monitoring (DDM) feature common in many modern SFP transceivers is defined by reference to the industry-standard SFF-8472.
SFP transceivers support SONET, Gigabit Ethernet, Fibre Channel, and other communications standards. Due to its smaller size, the SFP has replaced the gigabit interface converter (GBIC) in most applications and sometimes referred to as a Mini-GBIC. Different types of SFP can be categorized and classified in general by temperature, speed and distance depending on the application as described by the SFF Committee. The engineered SFP can be a form of dual fiber with LC connectors and a single fiber with SC or LC connector. Single Fiber Bi-Directional Gigabit SFP Transceivers, are paired as BX-U and BX-D for Uplink and Downlink respectively. SFSW – Single Fiber Single Wavelength transceivers, for bi-directional traffic on a single fiber.
SFP copper electrical host footprint is the same as SFP optical transceivers for common interface port operation using standard Category 5 unshielded twisted-pair copper cabling of maximum 100 meters max link that is terminated with RJ45 connector.