The Summer of Fiber

The Summer of Fiber

| 6/10/2012 8:08:10 AM

We will be publishing Tech Tips about the SFP family of transceivers this Summer. This month the topic will be SFPs. July will cover SFP+ and August will cover XFP.

 The small form-factor pluggable (SFP) is a compact, hot-pluggable transceiver used for both telecommunication and data communications applications. The SFP transceiver is not standardized by any official standards body but specified by a multi-source agreement (MSA) between competing manufacturers. Ethernet equipment today will often offer a few SFP ports in addition to fixed copper ports. SFPs provide great flexibility to the end-user, in that different speeds and fiber types can be installed in the same SFP port, dependent on the installation’s requirement. SFPs may offer DDMI (Data and Diagnostics Management Information) or not. Thus, with or without DDMI is standard verbiage tied to the identity of the SFP. If a managed switch, Layer 3 media converter or other intelligent Ethernet equipment offers SNMP management, then the SFP with DDMI will provide the end user the ability to manage and monitor the SFP for its output value, vendor serial number, type of fiber, and many other pieces of information.

SFPs are available in straight speed, such as Fast Ethernet and Gigabit, but there are also Multi-rate SFPs that support different speeds, offering, for example, 1Gig/2.4Gig/4Gig. SFPs, like their fixed transceiver counterparts, can support Single Strand Fiber (SSF), dual strand fiber, and CWDM. SFPs are not offered for 10G applications; SFP+ and XFP must handle that speed.

The SFP size dimensionally is different from the SFP+ and XFP. It is unlikely that an SFP can be installed and function correctly in an SFP+ or XFP cage. Fiber vendors have also implemented a way to identify what type of fiber the SFP is capable of by a using a particular color for the handle of the SFP itself.

Color of handles :

Dual Strand

Black pull ring is MM 850nm
Blue pull ring is SM 1310nm
Yellow pull ring is SM 1550nm

CWDM (all SM)
Purple pull ring is 1290nm, 1490 nm, 1310 nm (DFB*) and 1550 nm (DFB)
Gray pull ring is 1270 nm, 1470 nm
Blue (FP**) pull ring is 1310 nm, 1550 nm
Green pull ring is 1330 nm,1430 nm,1530 nm
Yellow pull ring is 1350 nm,1450 nm,1550 nm
Orange pull ring is 1370 nm,1570 nm
Red pull ring is 1390 nm,1590 nm
Coffee pull ring is 1410 nm,1610 nm

*DFB, Distributed Feedback Laser, a very high power fiber laser
** FP, Fabrey-Perot, and moderately high power fiber laser

In conclusion, SFPs have provided greater flexibility to the end user, and as more Ethernet equipment offer SFP ports, the price of the SFPs will lower in price, making it more cost-effective to install.

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