Speed testing gigabit ethernet network

I've recently used iPerf3 to test my cat5e ethernet network speed using a Windows 10 desktop PC and a docked Windows 10 MS Surface Pro 4, so both machines are connected over ethernet. The overall reported speed in either direction between both PCs is around 650Mbps which seems a bit low to me so I repeated the test with Task Manager visible on both machines, and noticed that the Surface Pro CPU usage spikes quite a bit at 100% during the test, whether using it as the iPerf client or server.

In terms of speed, when copying files between both machines I'm getting a reported speed of 50MB/s to 70MB/s (the same when copying to my NAS), but do these speeds seem reasonable for a cat5e ethernet network running through a Cisco managed switch?
I'm wondering if the CPU usage spikes on the Surface Pro are affecting the results?

I get 950 megabits per second from my Win10 PC to my Synology NAS through a managed TP Link switch.

If you have third party antivirus check that is not affecting.

In reply to a post by jchamier:

I get 950 megabits per second from my Win10 PC to my Synology NAS through a managed TP Link switch.

If you have third party antivirus check that is not affecting.

Good idea. I'll also connect both PCs directly to the switch via patch cable so that the test isn't running through the cat5e cabling throughout the house.

Assumimg your NAS is up to it then sustained 110MBps is what you ahould be getting using SMB on the network. At least thats what my Samba servers at work where doing a decade ago on NetBurst based Xeons with 6GB of RAM with 4Gbps FC attached disks with ext3. It was quite extensively tuned however.
These days it is all 10Gbps or better networking at work which takes also takes tuning to max out. That said at home I can get similar performance to what I was getting a decade ago with an Atom CPU and minimal tuning, though its a home built NAS running CentOS which given the day job is easier than some web based NAS system to administer and tune. Will be interesting to try multipath TCP SMB in due course.

I get around 950 megabits per sec. with iPerf3 testing my cat5e between an HP windows 10 desktop and another desktop with ubuntu-mate 18.04

This has 15 metres of cat5e between one machine and the switch and 20 metres of cat5e from that same switch to the other machine.

P.S. This is Just as guide or comparison maybe....

I got the same result previously about 2 years ago using my Old Vodafone router as the switch so to speak also...

P.P.S. I'm sure it shouldn't use anymore than minimal CPU... It should mostly be done by the networks devices...

Edited by mrmarktigger (Tue 28-Jan-20 21:19:59)

Its ethernet over cat5e or better cable and under 100m. The length of the cable is utterly irrelevant to the discussion at hand. That is it negociates a speed of 1Gbps or it doesn't and it just works at that speed.

Now you could have a suspect link, but just check for errors in the interface counters. These should be zero or very close to zero. If they are not then you most likely have a bad cable send it for recycling. Though it could be a bad switch port or even a duff switch, but the latter two options is very rare.

The most likely reason for not getting the full speed is a cheap ass network card. Realtek chipsets are not great (thiugh better than they used to be), others are even worse. Best is Intel then Broadcom. Basically while it might be able to negociate a 1Gbps link with the otherside many chipsets can't actually push 1Gbps of traffic or the chipset itself and/or the drivers are as buggy as hell.

This can be really apparent at 10Gbps, you can get a server to just pump out UDP traffic and then look at what the port throughput on the switch is (expensive enterprise grade ones) and well it might max out at 7Gbps or even less. One forgot about it at the 1Gbps level because it has not been an issue with the server grade kit I am used to working with for over a decade.

You�ve reliably missed the end to end part of the equation. The sending machine has to be able to send at 900 Mbps+ which it may not be able if the HDD is encrypted and using CPU to decrypt thus breaking any DMA to the NIC.

I have 950 Mbps from my Realtek NIC. I have more problems with Intel drivers for WiFi than any other vendor. They are awful. The Broadcom NIC�s on enterprise servers are great.

I am assuming that iPerf3 doesn't use the HDD at all as I am guessing it just sends a stream of data without reading or writing it from the hard drive. It wouldn't be a good test of network performance if it relied on the speed of a hard drive.