SFP-GE-S-2 VS. GLC-SX-MM: What’s the Difference?

SFP-GE-S-2 and GLC-SX-MM are Cisco 1000BASE-SX SFP multimode fiber transceivers. Since there are similar specifications for these two multimode modules, many end users may be confused when choosing a multimode fiber SFP LC connector SX transceiver for their Cisco switches. So, are they the same one? This post intends to give a simple explanation of SFP-GE-S-2 vs. GLC-SX-MM.

SFP-GE-S-2 Module

Cisco SFP-GE-S-2 is a 1 GbE SFP SX fiber transceiver that supports the maximum data rate of 1Gbps. It’s compatible with the IEEE 802.3z 1000BASE-SX standard, and can operate on standard multimode fiber optic link spans of up to 2 km.

Module/Specs	Cisco SFP-GE-S-2
Interface	LC duplex
Wavelength	1310nm
Tx power	-9.5 ~ -3dBm
Receiver Sensitivity	< -17dBm
DOM Support	Yes
Temperature Range	32℉to 158℉ (0℃ to 70℃)
Data Rat	1G
Fiber Mode	MMF

GLC-SX-MM Module

GLC-SX-MM transceiver is also a Cisco 1000BASE-SX fiber transceiver that designed for Gigabit Ethernet applications. This SX module is compatible with the IEEE 802.3z 1000BASE-SX standard, and can operate on standard multimode fiber optic link spans of up to 550m.

Module/Specs	Cisco GLC-SX-MM
Interface	LC duplex
Wavelength	850nm
Tx power	-9.5 ~ -3dBm
Receiver Sensitivity	< -17dBm
DOM Support	No
Temperature Range	32℉to 158℉ (0℃ to 70℃)
Data Rat	1G
Fiber Mode	MMF

SFP-GE-S-2 VS. GLC-SX-MM

From the above specs comparison, we can learn that these two SX multimode modules support same data rate and operating temperature range. They all can operate on the multimode fiber optic cables. The main differences include:

• Wavelength

SFP-GE-S-2 can support a wavelength of 1310nm, whereas GLC-SX-MM works in 850nm.

• Transmission Distance

SFP-GE-S-2 can support up to 2km over laser-optimized 50 μm multimode fiber cable, while GLC-SX-MM can operate on legacy 50 μm multimode fiber links up to 550m.

• DOM Support

SFP-GE-S-2 can support DOM, but GLC-SX-MM does not have DOM function. DOM (Digital Optical Monitoring) is an important function available on fiber optic transceiver. It allows users to monitor parameters of modules, such as optical output power, optical input power, temperature, laser bias current and transceiver supply voltage. In real time, it offers users more convenience when using optical modules.

• Price

GLC-SX-MM is a legacy model, it doesn’t feature DOM function. It comes with the lowest price compared with other SX modules . Take FS.COM compatible transceivers as example, SFP-GE-S-2 costs $ 11.00, while GLC-SX-MM is only $ 6.00.

Conclusion

From the contents above - SFP-GE-S-2 vs. GLC-SX-MM, we can draw a conclusion that these two SX multimode fiber transceivers nearly can be used as the same one type module sometimes, but their existing differences still differ them from some applications. Most of the Cisco switches and routers support all two models, but please note, some of the switches require different models, you may visit Cisco SFP Compatibility Matrix for more detailed information.