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What are SFP's?

What are SFP's and How do They Work?

High-end networking demands high-end equipment. You have a plethora of options, but eventually you have to make decisions on which technology covers each of your applications. When considering all of those options, an understanding of SFP transceivers is pivotal. It’s a core technology that serves as a primary workhorse in many networks. This guide is going to explain all about SFP and it’s primary uses.

SFP Overview

Starting with the basics, SFP stands for small form-factor pluggable. It’s also commonly called mini-GBIC (gigabit interface converter). SFP is a popular transceiver for three main reasons. First is the small form factor. It’s size allows it to be used in tight networking spaces to provide fast communication between switches and important networking components. The second reason for its proliferation is the variety of SFP connection options. SFP works with copper or fiber optics. The networks that can’t utilize SFP are scarce. Finally, SFP is hot swappable. That makes it ideal for expanding or adjusting existing networks without having to redesign the entire cable infrastructure.

SFP Variety

SFP is designed to work with the bulk of modern networks. On the copper side, you will primarily find 1000BASE-T and 1000BASE-TX modules for gigabit Ethernet networking. SFP modules are excellent for bridging communications between switches in compact environments, provided everything is within 100 meters.

On the fiber optics side of the equation, options are massive. SFP modules are made to support singlemode and multimode fiber. It works with simplex and duplex. Wavelength options range from 850 nm to 1550nm. Networking ranges are anywhere from around 500 meters to over 100 km. In all, there’s an SFP module for every job.

SFP Compatibility

SFP compatibility is deceptively tricky. There is not a formal, regulated international standard for these modules. Instead, compatibility is found within the multi-source agreement (MSA). This is an agreement supported by a number of manufacturers that work together to try and provide a reliable means of mixing and matching SFP brands successfully.

The challenges is that, despite the MSA, SFP modules tend to work best when brands are not mixed. It creates an interesting obstacle for optimizing equipment costs. You can follow MSA guidelines and try to use lower-cost parts in different components of your network, or you can simplify compatibility and stay within a single brand. The trade-off is usually between equipment costs and deployment time, but overall, MSA compatibility can be used successfully in most networks.

Applications of SFP's

With all of this talk about SFP, the inevitable question arises. When is it useful? SFP has a wide reach of applications. For copper modules, the most common use (as mentioned before) is bridging network switches. They provide fast copper connections without requiring bulky equipment.

In the realm of fiber optics, the applications cover anything that might involve high-speed and/or long-range cables. High-definition audio transmission and reception, passive optical networks (PON), multiplexing and simplex networking are some of the most common uses of this technology. The variability of SFP allows it to provide modules for any of these connections, and it provides a range of options in cost, speed, range and accessibility.

Advanced SFP

Since the development of SFP, modernized advancements have been added to the mix. Namely, SFP+ and QSFP are now available. SFP+ is a faster version of the same form factor. It supports speeds up to 10Gbps, and it typically works across shorter distances. SFP+ ports are usually compatible with SFP optics, but the reverse is not true. SFP+ cannot operate slower than 1Gbps.

QSFP (quad small form-factor pluggable) is another transceiver with a range of support options. Ethernet, InfiniBand, SONET and fiber channels are all supported. The primary difference between QSFP and SFP is the quad form. QSFP can hit speeds up to 100 Gbps by utilizing four transmission and reception channels. QSFP is the powerful upgrade for systems that require huge bandwidth.

Complete mastery of SFP modules requires more learning that might fit in a single article, but this is enough to get started. What matters is that you understand how frequently SFP modules can be used to bridge communications between devices. From there, it’s a matter of matching the SFP design to the rest of the network.

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