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RJ45 vs SFP Port: Which One to Choose?

Sep. 16, 2022

Choosing between an SFP port or an RJ45 Ethernet port for 1000Mbps connectivity to an access switch is always a question of choice. RJ45 ports versus SFP ports, many people want to know the main differences between them. Is an RJ45 port or an SFP port right for your network? As RJ45 and SFP ports are already familiar to most users, here are some principles we can follow to choose between RJ45 and SFP ports.


Differences between RJ45 and SFP ports in a 1000Mbps connection


Connection type

This is the most basic difference that determines many of the other functions of an RJ45 port versus an SFP port, so we have placed it at the beginning. RJ45 ports support Cat5, CT6 and other RJ45 network cables and are commonly used to connect computers or routers. what is the purpose of an SFP port? In terms of SFP switches, the SFP ports are more versatile and can accept fibre optic SFP modules with fibre optic cables (single mode and multimode) as well as copper SFP modules with Cat5e, Cat6, Cat7, and Cat8 cables.

Hilink 200G QSFP56 SR4 Optical Transceiver

Hilink 200G QSFP56 SR4 Optical Transceiver

Maximum distance

The maximum transmission distance varies greatly due to the use of separate RJ45 and SFP port connections. the maximum distance supported by the RJ45 port is 100 m, which is more than sufficient for a home or small office network. the SFP port allows for longer distances. MMF cables up to 550-600 metres and SMF cables up to 150 km can be connected to the SFP port. If connected using a Cat5 cable, the SFP port follows the 100m limit.


In fact, another related type of network switch port appears here, the combo port. For example, this S5800-8TF12S switch comes with eight 1G SFP/RJ45 combo ports and 12 1G/10GE SFP+ ports. These 8 combo SFP/RJ45 ports allow users to use either the SFP port or the RJ45 port for short-distance connections at a time, as opposed to the SFP/RJ45 ports.


Hilink 100G QSFP28 ZR4 Optical Transceiver

Hilink 100G QSFP28 ZR4 Optical Transceiver

Considerations for choosing an RJ45 or SFP port

We now know that when the link distance exceeds 100 meters, it is important to consider using an SFP port with a fibre optic SFP module rather than an RJ45 Ethernet port with an Ethernet cable. Here are some other principles to consider when deciding whether to use an RJ45 or SFP port.


  • Security. In some worse cases, using a fibre optic SFP module is safer than a Cat5e/Cat6 RJ45 Ethernet cable, which uses current and is, therefore, more prone to fire/flash, whereas a fiber optic SFP module has no such problems.


  • Reliability. Due to its characteristics, fiber is generally considered to be more reliable. RJ45 Ethernet cable is at risk of EMI (electromagnetic interference) as it uses electrical signals that are susceptible to a number of external factors such as high voltage.


  • Latent. When connecting devices over considerable distances, SFP ports have lower latency than RJ45 ports which may provide poorer service.

    Hilink 10G Copper RJ45 SFP+

    Hilink 10G Copper RJ45 SFP+

  • Energy consumption. SFP ports consume less power than RJ45 ports. The difference in consumption can be more pronounced, especially in larger networks.


  • Future network upgrades. If you plan to migrate to higher bandwidths such as 10 Gbps in the near future, SFP ports supporting fiber optic cables are more forward-looking than Cat5e/Cat6 RJ45 Ethernet cables.


  • Cost. Since RJ45 Ethernet ports and SFP ports operate at virtually the same speed, it may be more economical to choose an RJ45 port to connect to an Ethernet switch, as Cat5e/Cat6 cables are less expensive than an SFP connection using both a transceiver and the corresponding cable.


Hilink (HAILI LINK) Technology Co., Ltd. is specialized in fiber optical products and networking solutions. Our main products are transceiver modules such as QSFP, QSFP28, CWDM/ DWDM SFP/XFP. Our networking solutions are including FWDM, DWDM CWDM OLP, MPO AAWG, etc. In order to provide better service for our customers, we also supply other kinds of related fiber optical products. Our products and solutions are largely applied in cloudy computing, data center, networking access, and so on. For more information and consultation, contact us here!  


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