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Maximising Gigabit Network

Last response: in Networking
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September 30, 2008 7:06:46 AM


Hi guys,

I am trying to maximising the bandwidth of my gigabit network.

I have a desktops connected using Cat5e cables over a gigabit network. My maximum transfer rate is about 23MB/s. I am using an onboard gigabit (realtek) on my motherboard (MSI) and the other computer on a PCI network card. The transfer rate on a 10/100 network is about 6MB/s. I used to achieve about 30+~40MB/s on the network interface on my old motherboard with the same computer connected.

My questions are:

1. Is the speed an average of what a gigabit network?

2. Will installing a new network card on the computer using the onboard gigabit interface improve the speed?

3. It seems that the onboard network interface is limited to USB speed? How do I know that it is limited to a certain speed?

4. How can i further improve the speed?

Thank you.

September 30, 2008 6:20:54 PM

Did your OS change when you upgraded to the new computer?
October 1, 2008 2:26:35 AM


Both the PCs are on WinXP Pro.
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October 1, 2008 1:46:22 PM

On-board gigabit should perform as gigabit - nothing else - otherwise this wouldn't make sense.

Is it in full duplex mode?
Do you have updated drivers installed?
Anything else is using the bandwidth when you perform the test?
October 3, 2008 9:33:32 AM

yes it's in full duplex mode.

i have the latest drivers.

nothing that is hogging the bandwidth is running.

by the way what is your maximum speed achieved on the gigabit network?
October 3, 2008 8:23:11 PM

I avg 25 to 30 MB /sec on my gigabit network at home. From what I've read regarding this topic on here in the last week or so, 25 to 35 seems to be the average.

Environmental variables might be at play as well. You didn't run the cables any differently then before eh?
October 4, 2008 9:44:10 AM


i see, then my network is working ok.

but for a typical 10/100 network, the speed achieved can be up to 6MB/s which is half of the theoretical limit of the 10/100 network.

then why does a gigabit network only able to achieve (with the same hardware) less than 25% of the theoretical limit?

guys, thanks for the interests and answers.
October 7, 2008 4:27:46 AM

A lot of system factors can influence LAN performance, this can turn into a tricky issue.

1. Gigabit networks can really achieve gibabit speeds. About 920 Megabits per sec is the theoretical max. (note that's "bits" not bytes). But you'll never see these speeds if you're using FTP. Hard drives are slow by comparison.

2. Maybe. Some network controllers use lots of CPU cycles xmit & rcv data (rather then HW offloads). Performance could suffer when your system is busy if you have that kind of Ethernet controller. I don't currently have any Realtek stuff... I can't say how their work.

3. Onboard Ethernet is not limited by USB. Different HW, different driver models, different needs.

- Both ends of the wire are important. System A may have a great adapter but if System B is crap, that's what you'll see in any performance run.
- Hard Disk to Hard Disk data transfers via FTP will be limited by the drive and controller at each end of the wire. (FTP is no speed demon either).
- Does your network support Jumbo Frames? Eabling this feature can really help with file transfer traffic (but hurt if you have a lot small packets).

LAN vendors tend to test their configurations with Chariot which is more of a memory to memory benchmarking tool that uses several remote computers to simulate different traffic patterns (if want to measure consistent performance you need to work around HW limiters that you have no control over).

Good luck
!