SFP Module: What’s It and How to Choose It?

SFP module that has been an industry workhorse for over 15 years is going to be explored in this post, SFP module types and applications and how to choose suitable SFP module are included.
SFP Module What’s It and How to Choose It-BP

Optical transceiver is widely used to connect network devices like switches, NIC (network interface card) and media converters, which make them necessary in fiber optical connections. SFP module that has been an industry workhorse for over 15 years is going to be explored in this post, SFP module types and applications and how to choose suitable SFP module are included.

What Is SFP Module?

SFP module, also known as small form-factor pluggable or mini GBIC (gigabit interface converter), is a compact, hot-pluggable optical transceiver module which is widely used for both telecommunication and data communications applications. Its SFP port accepts both optical modules and copper cables. That’s why it’s developed and supported by many network component vendors. The SFP transceiver module is not standardized by any official standards body, but rather is specified by a multi-source agreement (MSA). And SFP module also supports SONET, Gigabit Ethernet, Fibre Channel and other communication standards. In addition, SFP has replaced GBIC in most applications because of its small size.

How Many Types of SFP Module?

SFP transceiver module comes in various types on the basis of different classification standards. There are single mode SFP module and multimode SFP module according to the cable type, which allows users to select the appropriate transceiver according to the required optical range for the network. And the transmission rate of SFP module is available from 100Mbps up to 4Gbps or more. Working distance of these SFP transceiver modules can be from 500 meters to 100 kilometers. CWDM SFP module and DWDM SFP modules are also available for WDM links. In addition, copper SFP module allows communications over twisted pair networking cables. Here is a simple classification of SFP modules.The following table is a simple classification of SFP modules. For more detailed information about SFP transceiver module, please read How Many Types of SFP Transceivers Do You Know

SFP TypesTransceiver TypeConnectorDistanceData Rate
SFP Fiber ModuleSX, MX, LX, EX, ZX, EZX, BXLC Duplex100m-160km over MMF or SMF100Mbps/ 1000Mbps
CWDM/DWDM SFPLC Duplex10km-120km over SMF
SFP Copper Module1000BASE-TRJ45100m over Copper Twist Pair Cable1000Mbps
10/100BASE-TRJ45100m over Copper Twist Pair Cable100Mbps
10/100/1000BASE-TRJ45100m over Copper Twist Pair Cable1000Mbps

Usually, SFP ports are found in Ethernet switches, routers, firewalls and NIC cards. SFP modules connect a network device to a fiber or copper network cables like Cat5e. And other types of SFP optical transceivers like 3G video SFP, 12G video SFP are also used in HD camera or monitoring systems.More information about HD video transceiver has illustrated in this post: Understanding Video SFP Transceivers

Common Questions About SFP Module

1. DDM, DOM, RGD-What functons do they represent?

DDM, DOM and RGD are common in SFP transceiver names, which make users confused. In fact, DDM (Digital Diagnostics Monitoring) is a technology which enables users to monitor real-time parameters in SFP modules like input power, output power and temperature. DOM (digital optical monitoring) is similar to DDM, allowing users to monitor parameters of the SFP transceiver. RGD means the SFP is a “rugged” grade transceiver that is well fit for industrial networking applications such as manufacturing automation, substations and smart transport systems.

2. What’s the difference between singlemode SFP and multimode SFP?

There are three main differences between singlemode SFP (SMF SFP) and multimode SFP (MMF SFP). The first one is the fiber cable used with them. Singlemode fiber has a smaller core than multimode fiber, and it allows unlimited bandwidth and lower loss. While multimode fiber can propagate multiple modes of light. The second one is the transmission distance. Singlemode SFP transceiver is often used in long-run links up to 120km, but multimode SFP module is used in short applications. The last one is the cost. Singlemode SFP is more expensive than multimode SFP due to the use of different light emitting unit.

3. What’s the difference between SFP and SFP+?

SFP and SFP+ have the same size and appearance. The main differenceaa between SFP and SFP+ is that SFP is often used for 100Base or 1000Base applications, while the SFP+ is used in Gigabit Ethernet applications. And the data rate and transmission distance of them are also different. For example, SFP supports speed up to 4Gbps Fibre Channel transceiver, while the speed of SFP+ transceiver is up to 10.3125Gbps.

4. Can we use SFP hardware in SFP+ slots?

In many cases, SFP+ port accept SFP optics, but the speed will be down to 1G instead of 10G. However, SFP+ optics cannot be plugged into SFP port, because SFP+ does not support speed under 1G. In addition, almost all SFP+ ports on Cisco switches can support SFPs, but many SFP+ ports of Brocade switch only support SFP+ optics.

5. How to maintain SFP module?

Generally speaking, there are several aspects to maintain SFP transceivers.Optical port protection. Keep the end face clean; avoid prolonged exposure the SFP port in the air; avoid scratching the end face or sleeve, etc.Use the SFP module correctly. Keep the optical transceiver work in the normal level; plug and insert the SFP transceiver gently to reduce accidental damageKeep the using environmental humidity of SFP transceiver is normal.

What to Consider When Choosing SFP Module?

When it comes to buying SFP modules, Cisco SFP modules are the preferences for many users. However, as the prosperity of optical transceiver market, a multitude of third party optical transceiver vendors begin to offer cheaper SFP modules which have the same performance with Cisco SFP. Then what to consider when selecting 1G SFP modules?

SFP Module, buy SFP modules

SFP Module Compatibility

When purchase third party SFP optical transceiver, 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 ask the sales rep for details about the SFP transceiver compatibility.

New SFP Module and Second-Hand SFP

There are both new and second-hand SFP transceiver in the market. Learn to discriminate them can avoid unnecessary loss. Usually the used SFP module may have scratches in its appearance and optical port, which is the basic method to tell from it. Besides, test the optical power, and compare the test result with the specifications is another effective way. If the result is much different, be careful, it may be an second-hand SFP module.

SFP Module Price

Compared with Cisco SFP or other brand SFP modules, third party SFP optical transceivers are more cost-effective. Under normal conditions, except for the price, there is no difference between the performance of compatible 1G SFP and OEM SFP modules. That’s why compatible SFP modules are popular in market. Users can choose the right compatible SFP optical transceivers from reliable vendors according to their need with a cheap price. Click to check SFP Module Price List on FS.COM.

Temperature Stability

SFP transceiver module is mainly used in data centers or on switches where the temperature maybe different in a large range. Too high or two low temperature can affect the optical power and optical sensibility. Therefore, the temperature stability is an important factor to ensure SFP module work normally.

SFP Module Quality and After-Sale Service

Nobody can ensure the SFP modules received are 100% normal. And the service life of optical transceiver is generally 5 years among many vendors. It’s difficult to tell the quality is good or bad in the first year. Therefore, choose a reliable vendor is important.

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