What Exactly Is an SFP Module?

SFP stands for small form-factor pluggable, also known as mini-gbic (gigabit interface converter). An Ethernet SFP module is simply a small modular transceiver that plugs into an SFP port on a network switch or server. SFP transceiver has replaced the GBIC module in most applications because of its small size, allowing it to be used in tight networking spaces to provide fast communication between switches and important networking components. The Gigabit SFP module is hot-pluggable, which makes it easy to adjust existing networks without having to redesign the entire cable infrastructure. See more details about Ethernet SFP module types in the following video.

What is the maximum link distance between two SFP ports? It depends on the SFP module and fiber cable. Different optical modules and fiber optic cables determine the max transmission distance.

Take an SFP 1G port as an example. It usually supports the copper module, fiber module, and DAC cable.

• If you use a 1000BASE-T copper SFP module, the max distance reaches 100m over the cat5e cable.

• If you use a fiber SFP module, the max distance reaches 180km over single mode OS2 fiber cable, or 550m over multimode OM2 fiber.

• If you use an SFP DAC cable, the max length only supports around 10m.

What is the mainstream speed for SFP ports?Definitely, 1Gbps and 10Gbps speed is the most common type. But the answer is typically applied to the usual enterprise network, and we should say 8G or 16G SFP for the storage networks.

Can you aggregate multiple SFP ports?Of course, you can. Link aggregation can provide more bandwidth, redundancy, and load-balancing benefits. That will ensure that one link can immediately switch to a second available link when it fails. So, it is critical for enterprise networks where performance and security are more important.

Sidenote: Make sure you have configured both switches for link aggregation before connecting these ports. Otherwise, it will cause network loops.

Can you connect SFP ports on switches from different brands?In most cases, you can connect them with different brand switches. But in some cases, you maybe connect them failed.

However, it would be best if you took care of the below tips.

• Use the SFP module with the same wavelength on the two slots. But for the BiDi transceiver module, choose the opposite wavelength on two slots. The wrong wavelength will cause failed connectivity. For example, when you use 1310nm-TX/1550nm-RX on the side A, you should connect them with 1550nm-TX/1310nm-RX on side B.

• Check the switch and SFP module compatibility prior. Some large brands like Cisco locked their SFP slots from generic SFP transceivers. Therefore you should better choose an original transceiver. However, You may also order third-party compatible transceivers because those are usually budget-friendly and help to save a lot of money.

• Ensure to use correct and quality fiber cable. A wrong fiber cable may shorten the link distance and even fail the link in some wholes. Remember the SMF SFP transceiver only support single mode fiber, while the MMF SFP transceiver only supports multimode fiber (to achieve the longer distance, use OM3 fiber cable instead of OM2 fiber cable)

How Many SFP Ports Does a Switch Have?The number of SFP ports on a switch may vary depending on different types. A cheap SOHO switch may only have RJ45 port, but no SFP port.

However, a typical enterprise switch for large networks may have 48 SFP fiber ports and one console port. That is because equipped with as many ports as possible to improve the density and throughput.

What is an SPF port? Suppose you are a “new man” in the networking industry. SPF port is the typing error of it. Because they are unfamiliar with this word, some guys may mistype it and call it SPF port. In fact, they are the same thing. Similarly, some guys may call SFP+ as SPF+ port, so remember they are the same thing. 

Additional Learning Hub Resources

What type of connector is SFP fiber？

How do you connect SFP to fiber optic cable？