SFF (Small Form Factor) and SFP (Small Form-Factor Pluggable)

From Xmultiple Engineering Manager.


The Small Form Factor (SFF) market is moving towards SFP Transceivers and products and this is the main point of this forum discussion.

The initial wave of fixed small form factor (SFF) transceivers on equipment has now been overtaken by the SFP version. SFP transceivers offer a key advantage to equipment vendors and end-users in the ability to support short wavelength (850 nm) or long wavelength (1310 or 1550 nm) in the same slot. SFP transceivers also offer big benefits for the equipment vendor since pluggables drastically reduce the complexity of their product line and associated inventory.

As an increasing number of equipment vendors offer SFP-based modules for Gigabit Ethernet and Fiber Channel switches and network interface adapters, the LC connector has become the defacto standard for SFP transceivers for Gigabit Ethernet and Fiber Channel. The vast majority of SFF transceiver manufactures only offer LC transceivers in the SFP version.

The adoption of SFF connectors in electronics was the signing of a Multisource Agreement (MSA) for SFF transceivers by many large connector and transceiver companies. As a result of this agreement, the signatories agreed to develop specifications for transceivers based on common packaging and pinouts (independent of the type of SFF connector used). This allows euipment manufacturers to design electronics based on a common transceiver form factor, available from multiple vendors. The end result is that multiple SFF interfaces was to provide a form factor standard supported by most companies in the transceiver and connector industry while providing a common form factor which also maintaining inventory flexibility through a common PCB design.

The SFF Transceiver standards group including some of the same companies who later developed a similar MSA standard for SFP (Small Form Pluggable) interfaces. In addition to the advantages offered by the SFF specification, the SFP specification allows for the use of short or long wavelength transceivers interchangeably on the same board or NIC card, depending on the best fit for the customers¡¦ infrastructure.

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