ilteris kaplan blog

Converting from gigabit to 10 gigabits

March 24, 2020

Using RJ45 or SFP Port

It is always the case to decide whether to choose a switch with access port of SFP port or RJ45 Ethernet port for 1000Mbps+ connections. So RJ45 port vs SFP port, which one would be better? There are some principles we could follow.

The first principle is appropriate for any cases of 1000Mbps deployment. That is, when the distance of the run is over 100 meters, SFP port with fiber SFP module must be considered instead of copper RJ45 port & copper cable.

Security: Using fiber SFP module is better than Cat5e/Cat6 RJ45 Ethernet cable in some of the worst circumstances. RJ45 cable uses electric current so it is easier to catch on a fire/lightning while fiber SFP module has no such problem.

Reliability: Fiber is often considered more reliable due to its properties. Copper RJ45 Ethernet cable has the risk of interference since it uses electric signals. The issue is usually called EMI (Electromagnetic Interference) when the electric signal is affected by some external elements, such as something with high voltage. So when the cable run is going through some places that the electric signal can be interfered, choose fiber rather than copper RJ45 cabling.

Future Network Upgrade: If you’re planning to move to higher bandwidth, e.g. 10 Gbps, in the near future, fiber optic cable is more future-proof compared with Cat5e/Cat6 RJ45 Ethernet cable.

Cost: Since Rj45 Ethernet port and the SFP port actually run at the same speed, choosing the RJ45 ports to connect the switches might be more economical since Cat5e/6 cable is lower-priced than the SFP connection with both transceiver module and the corresponding cables. is good for getting 10gbe speeds.

Written by Ilteris Kaplan who still lives and works in New York. Twitter