I recently experimented with some 10G-Tek 1/2.5/5/10G to RJ-45 SFP+ modules, and after setting them up today, they seem to be working well. I have one module plugged into a Dell N2048P and another into a Netgear M4350-48, both of which are showing 10G speeds. However, I'm running a Cat-5E cable that could be anywhere from 20 to 40 meters long, leading me to wonder if the connections are really capable of 10G speeds or if they're being limited by the RJ port compatibility. I'd appreciate any insights on how to determine the actual negotiated speed between these devices, especially since the switch claims compliance with 10GBase-SR but may not indicate the real speed due to the RJ-45 adaptation.
4 Answers
Keep in mind that 10G links won’t automatically adjust to lower speeds based on cable quality. You might need to conduct tests under load and check for errors to determine if you need to force a lower speed on both ends.
You can also explore using tools like netcat or socat, and don't forget to check interface counters via SNMP for any dropped packets or errors, which could indicate speed issues.
The best way to check actual speed is to run an Iperf test using just two devices at each end of the cable. Cat-5E can theoretically support 10G for short distances, so running that test will give you a clear idea of what you're getting.
If you're using Linux, you can try using 'ethtool' with the '-m' option to check the SFP module's internal parameters. It might give you some insights, but keep in mind the module can only report data that the port expects.
True, but you might not get accurate info unless the manufacturer has built in a way to check the data rates. Typically, SFP modules won’t show anything outside the standard.
Absolutely, Iperf is the way to go! Just run a single test initially, and you can use options like -P 8 to push multiple threads if your devices can handle it.