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What is the difference between Cisco SFP and GBIC?
Knowledge Base + 2024.01.05

Cisco SFP (Small Form-Factor Pluggable) and GBIC (Gigabit Interface Converter) are both transceiver modules used in networking equipment to convert electrical signals to light signals for transmitting data over fiber optic cables.

The main difference between Cisco SFP and GBIC is their size. SFP is a smaller and more compact form factor compared to GBIC, making it suitable for higher port densities in networking equipment. SFP modules also offer higher data transfer rates and lower power consumption compared to GBIC modules.

In terms of compatibility, SFP modules are compatible with SFP slots, while GBIC modules are compatible with GBIC slots. However, there are also devices that support both SFP and GBIC modules using different slots.

Overall, the choice between Cisco SFP and GBIC depends on the specific networking requirements, such as port density, data transfer rates, and power consumption.

What is GBIC?

GBIC is short for Gigabit Interface Converter. It is a hot-pluggable interface device that converts Gigabit electrical signals into optical signals. GBIC standard is first defined in 1995. Then GBIC modules are commonly used in Gigabit Ethernet and Fiber Channel by connecting to transmission media like fiber optic cables and copper cables. GBIC got popular in the 1990s. The GBIC connector is designed to support reliable operation at 1Gbit/s in the form of SC duplex connectors.

The typical GBIC transceiver include 1000BASE-SX GBIC, 1000BASE-LX/LH GBIC, and 1000BASE-ZX GBIC. They cover short, long, and extended wavelengths. Their specifications are shown in the following table.

GBIC Module Options

Module Type




Cisco Product Number









(H x W x D)

0.39 in. x 1.18 in. x 2.56 in.

(1 cm x 3 cm x 6.5 cm)








70 to 100km

GBIC vs SFP, What are the differences?

GBIC vs SFP connector. All GBIC modules use SC connectors, and SFP modules use LC connectors. So when installing a GBIC module, you need a duplex SC fiber, while LC fiber is used for installing an SFP module.

GBIC vs SFP size. SFP is an upgraded version of GBIC. The most significant enhancement of SFP is the size. This SFP is smaller than half the size of GBIC, as shown in the following figure. A smaller size means higher density SFP ports are available on the same switch panel. It is the main reason why GBIC was replaced by SFP.

GBIC vs SFP compatibility. GBIC module has no variants, but SFP has variants such as SFP+ and SFP28, bringing speeds up to 10 Gbit/s and 25 Gbit/s. They have the same size as SFP, so SFP+ and SFP28 modules are backward compatible with SFP when the SFP module is plugged into SFP+ and SFP28 ports.

SFP or GBIC, How to choose

Firstly, if your switch or router is ready, how to choose between SFP and GBIC depends on your switch or router slots. SFP is not compatible with GBIC. Switches with only GBIC slots allow GBIC modules only, and so do SFP switches.

If you don’t have an existing switch or router, it is recommended to choose SFP equipment because SFP has many advantages over GBIC, such as higher density, better interoperability and compatibility. Most importantly, the fact is that GBIC has been replaced by SFP in practical applications. GBIC has become thoroughly outmoded, SFP is your right choice now.