An introduction to Cisco SFP transceivers

SFP Transceivers: A Primer

The small form-factor pluggable (SFP) transceiver is a compact optical transceiver used in optical communications for both telecommunication and data communications applications. SFP is the interface between a network device mother board and a network cable, and is a very popular format that’s endorsed by several fiber optic component companies.

SFP transceivers are capable of supporting SONET, Gigabit Ethernet, Fibre Channel, and several other communications standards. In the near future, it’s going to expand to SFP+ .Then, data rates of 10 Gbits/s will be possible, including 8 gigabit Fire Channel. SFP+ modules have some of their circuitry on the outside, as compared to Xenpac or XFP type modules which have everything inside.

There is a great variety of SFP transceivers available each with different transmitter or receivers. This allows the user to configure and customize the transceiver to get the proper optical reach with either multi-mode fiber or single-node optic fiber type.

There are four categories of optical SFP modules – SX, which is 850nm, LX, which is 1310 nm, ZX, which is 1550 nm and DWDM. They all have an interface of copper cable, which allows a host device to communicate via USTP (unshielded twisted-pair) network cable. CWDM and single-optic cables also exist, and they are 1310/1490 np upstream and downstream.

SFP transceivers have capability of transfer rates of up to 4.25 Gbit/s. XFP, which is a slight variation, increases this amount by nearly three times, at 10 Gbit/s.  The SFP transceiver is specified and made compatible via a multi-source agreement between manufactures, so that different users who may use equipment from different manufacturers can work without worrying about errors and inconvenience. The GBIC interface is the precursor to the SFP, hence its nickname as mini-GBIC. There is a similar transceiver called SFF, which is about the same size as the SFP. It is socket-mounted rather than slot-mounted, ie attached directly to the motherboard rather than plugged directly into a PCI or other expansion slot.

Digital optical monitoring functions are supported by SFP transceivers, all going by the specifications of the SFF-8472 MSA. The user, because of the DOM capabilities, has the ability to constantly monitor real-time parameters of SFP like optical input/output power, supply voltage and laser bias current.

PC Wholesale carries SFP transceviers for all Cisco devices, as well as SFP Transceivers for many other manufacturers.