Why does my 100Mbps/s connection only get 50+Mbps?

[MichaelD]

This is on a LAN, with quality cabling, 24-port rackmount switch, etc.

I'm transferring a large file internally; the file is 38GB. That would qualify as a "large file."

BOTH systems are connected to the same switch, directly. Nothing in between. Both have 100Mbps/s NICs, yet I'm seeing like 50Mbps. WHY?

This is firstly annoying.,..and secondly perplexing. I understand "overhead." But 50Mbps of "overhead?" I call BS.

Explain.

 

[DaveSimmons]

Network speed specs seem inflated for all speeds.

I remember benching 10 mbps years ago and only getting about 337KB instead of 1,000KB so 50% of rated speed doesn't sound too bad.

WiFi is slow too, "11 Mbps" typically only gives 3-4 Mbps even when everything is in the same room. I read a lot of reviews when I was first thinking about a B setup a couple of years ago, and regardless of brand and test setup the actual performance was this bad.

 

[Viper96720]

Maybe the harddrive don't think hardrive can read and write that fast.

 

[Vegito]

Do you know if the switch is managed or unmanaged.. auto sensing, etc.. mainly duplex.. full or half.. lots of things.. collision, etc.. unplug the other 22 people and try again

 

[karnick]

have you tried cat6 wire/gigabit wire (i think they are the same).. if its available to you give it a shot to see if you can find out whats slowing you down

 

[VirtualLarry]

Well, one possible explaination is that there is some sort of "N-way" negotiation problems between the NICs on each side and the switch. What happens if you force the NIC settings to 100Mbit, full-duplex, on both cards? Additionally, if you are using Windows' file-sharing, using NetBIOS over TCP/IP, then have you checked your MTU settings, and RWIN settings? Most people find that they need to "tweak" their RWIN settings and adjust them upwards when they get broadband, perhaps it wouldn't be a bad idea to check them likewise. Another issue could be NIC settings on each machine, adaptive interrupts, bus-master DMA settings, etc. Have you tried a cross-over cable, to determine if the switch is at fault here somehow?

 

[sparks]

Many times I find that its the switch that is the problem. Try transferring the same file between the 2 computers with a crossover cable and see if there is an improvement.