GBIC or SFP — Which One Is Your Choice?

As is known to all, fiber optical transceivers are developed along the way to achieve more compact sizes, such as GBIC, SFP, SFP+ and so on. Meanwhile, these transceiver modules are available with a variety of transmitter and receiver types, allowing users to select the appropriate transceiver for each link to provide the required optical reach over the available optical fiber type (e.g. multi-mode fiber or single-mode fiber). In addition, there are a variety of interface types of GBICs and SFPs, like 1000Base-SX, 1000Base-LX/LH, 1000Base-EX or 1000Base-T etc. Faced with so many choices, some people are confused when choosing the proper one for their project.

Recently many users ask when they choosing a card for their switch/router, they should choose either cards that take SFP or cards that take GBIC. It seems to be a headache for them because they are not clearly know the differences of them. The following will tell you when it’s best to use GBIC or SFP.

GBIC (gigabit interface converter)

GBIC is a hot-swappable input/output device that plugs into a Gigabit Ethernet port or slot, linking the port with the network. GBIC is a standard for transceivers, commonly used with Gigabit Ethernet and fiber channel. GBIC module is hot pluggable, this feature allows a suitably designed enclosure to be changed from one type of external interface to another simply by plugging in a GBIC having the alternative external interface. Generally, GBIC is with the SC connector. The GBIC standard is non-proprietary and is defined by the Small Form Factor committee in document number 8053i. The first publication of the proposal was in November, 1995. A few corrections and additions were made in September, 2000.


SFP (small form-factor pluggable)

SFP is a specification for a new generation of optical modular transceivers. The form factor and electrical interface are specified by a multi-source agreement (MSA). SFP is also known as a Mini GBIC as its function is somewhat similar to the GBIC transceiver while SFP is smaller than it. SFP transceivers are designed to support SONET, gigabit Ethernet, Fibre Channel, and other communications standards. Due to its smaller size, SFP is now more and more widely used for both telecommunication and data communications applications.


GBIC & SFP Interface Types

For every type of GBIC and SFP transceivers, it works with different wavelengths at a designated location or distance. For examples, SX SFP uses 850nm for a maximum of 550 meters, LX SFP uses 1310nm for a maximum 10km, ZX SFP could reach 80km or copper SFP uses a RJ45 interface. We can easily distinguish via the information in their names or models, ie. 1000BASE-T, 1000BASE-SX, 1000BASE-LX/LH, 1000BASE-ZX, 1000BASE-CWDM, or 1000BASE-DWDM. In addition, the DOM function for an SFP is discretionary. It supports the users to locate the real-time working status of SFP. The famous brand of GBICs or SFPs are Cisco, Finisar, HP, Juniper, Extreme Network and so on. There is a little difference in the features of each brand’s GBICs and SFPs and they support their corresponding brand’s switches/routers.

When it’s best to use GBIC and When to use SFP?

According to the above definitions of GBIC and SFP, you may have a further understanding on both of them. There is only one difference of them. SFP is smaller than GBIC. Because the smaller size of SFP (almost half the volume of GBIC), we can configure double number of ports on the same panel which increases the utilization rates of switches/routers. Other basic functions of SFP is almost the same with the GBIC and they are equal in performance. Though there are some users still using the GBIC as their old divice which can not be updated to support SFP, GBIC will gradually be obsoleted and replaced by SFP. So the answer to the question “When it’s best to use GBIC and When to use SFP?” is very noticeable.


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