Understanding Fiber Optics – Your Quick Guide to SFP TransceiversOptace
What is an SFP Transceiver?
SFP (small form-factor pluggable) is a compact, hot-pluggable optical module transceiver used for both telecommunication and data communications applications. These applications -usually on networking hardware- feature an SFP interface which is a modular (plug-and-play) slot for a variable, media-specific transceiver in order to connect a fiber optic cable or sometimes a copper cable.
The form factor and electrical interface are specified by a multi-source agreement (MSA) under the Small Form Factor Committee umbrella; a popular industry format jointly developed and supported by many network component vendors.
Types of SFP transceivers
There are a number of types of SFP Transceivers based on the different classification standards. To help you pick the best SFP Transceiver for your application, it is important to understand these different classifications and characteristics and more importantly, to tell them apart.
They may seem like a lot to digest, but not to worry. We have taken time to outline a summary of the most common classifications and differences, to serve as a quick guide to selecting the right SFP Transceiver.
Let’s explore them in detail…
Single Mode vs. Multimode SFP Transceivers
Based on the types of optical fibers SFP transceivers work with, SFP transceivers are divided into single mode SFP that works with single-mode fiber and multimode SFP that works with multimode fiber. Explore the major differences between them. Single-mode SFP transceivers are designed to transmit signals over long distances, while Multimode SFP transceivers are specially designed for short distance data transmission. Explore some more differences below…
|Single Mode SFP||Multimode SFP|
|Wavelength||1310nm and 1550nm||850nm|
|Colour Coding||Blue color-coded bale clasp for 1310nm SFP. Yellow color-coded bale clasp for 1550nm SFP.||Black color-coded bale clasp.|
|Fiber Jacket Colour||Yellow jacket for Single Mode fiber.||Orange jacket for OM1 & OM2 Multimode fiber|
|Transmission Distance||Long distance transmission such as 2 km, 10 km, 20 km, 40 km, 80 km, 100 km and 120 km.||Short distance transmission such as 100 m and 500 m.|
SFP Fiber Module vs SFP Copper Module
Copper SFP modules allow communication over twisted pair networking cables while fiber modules allow communication over fiber optic cables. Explore more differences below;
|Transceiver Type||Connector||Distance||Data Rate|
|SFP Fiber Module||CWDM/DWDM SFP||LC Duplex||10km-120km over Single Mode Fiber||100Mbps/ 1000Mbps|
|SFP Copper Module||1000BASE-T 10/100BASE-T 10/100/1000BASE-T||RJ45||100m over copper twist pair cable||100Mbps/ 1000Mbps|
Simplex SFP vs Duplex SFP
Simplex SFP transceivers use only a single fiber for transmission while Duplex SFP transceivers use dual fibers. Simplex SFPs, are also known as bidirectional (BiDi) SFPs. It is very easy to distinguish simplex SFP and duplex SFP from the receptacle as shown in the diagram below;
Note: All SFP transceivers should be used in pairs. For duplex SFPs at the two sides, we should connect two SFPs of the same wavelengths. For example, two 850nm SFPs or two 1310nm SFPs. However, for simplex/BiDi SFPs, we should use two SFPs that have opposite wavelengths for transmitter and receiver.
Bandwidth; SFP vs SFP+
The trend towards higher speed and higher bandwidth is always unstoppable, from Fast Ethernet to Gigabit Ethernet. At the same time, new devices for transmitting data are published; SFP+ for 10 Gigabit and SFP28 for 25 Gigabit Ethernet. While they all use the same form-factor packaging, the most obvious difference between them is the data rate. Explore the differences below;
|Data Rate||1.25G 2.5G/3G/4.25G||6G/8.5G/10G||25G|
|Types||Single-mode/Multimode Simplex/Duplex CWDM/DWDM||Single-mode/Multimode Simplex/Duplex CWDM/DWDM||Single-mode/Multimode|
|Distance||100 m up to 150km||220m up to 80km||100m up to 10km|
Dense Wavelength-Division Multiplexing (DWDM) vs Coarse Wavelength-Division Multiplexing (CWDM)
Simply put, Wavelength-Division Multiplexing (WDM) is a technology that enables transmission of multiple signals simultaneously on a single fiber. WDM is utilized by telecom systems in long distance transmission. In these systems, the lasers of SFP transceivers are chosen with precise wavelengths closely spaced but not so close they interfere with each other.
Wavelength-division multiplexing for SFP transceivers is either DWDM (dense WDM) or CWDM (coarse WDM). Discover more below;
|DWDM SFP||CDWDM SFP|
|Wavelength Spacing||Up to 45 wavelengths (Channel 17 to Channel 61 according to ITU) of C Band (1525 nm to 1565 nm) or L Band (1570 nm to 1610 nm) with a 0.8nm spacing||Up to 18 wavelengths from 1270 nm to 1610 nm with a 20nm spacing, i.e. 1270 nm, 1290 nm, 1310 nm, 1330 nm…|
|Transmission Distance||Up to 80 or 200 km||Up to 100 km, typically 80 km|
|Application||Long distance DWDM SONET/SDH transmission, Gigabit Ethernet, Fibre Channel, Metro Network||Gigabit Ethernet, Fibre Channel (FC), Metro Access Network, Point-to-Point Network, Synchronous Optical Network (SONET), SDH (Synchronous Digital Hierarchy).|
|Benefits||Up to 32 channels can be done passively. Up to 160 channels with an active solution. Active solutions involve optical amplifiers to achieve longer distances.||Passive equipment that uses no electrical power. Much lower cost per channel than DWDM. Scalability to grow the fiber capacity as needed with little or no increased cost. Protocol transparent. Ease of use.|
Quick guide to selecting SFP
When selecting the correct SFP transceiver, the main factor to consider is the application scenario based on the classifications outlined above. In summary,
-Which type of Fiber Optic Cable are you connecting to the SFP transceiver?
-At what data rate do you want to transmit?
-What is the distance of your link?
-What type of signal are you transmitting?
There’s one more important consideration technicians are careful to look into…
With quite a number of third party SFP optical transceivers in the market, compatibility is often the most parameter users care about. Before place your order, you can check the vendors’ optics testing center to confirm whether the SFP module you choose is compatible with your devices.
Or just talk to us for details about the SFP transceiver compatibility.