Jumbo Frame size question

[kk22]

Hi all,

New to the forum here so hello to all the experts.

I purchased a Trendnet TEG-S80G gigabit switch to help with file transfer speeds between the computers, all still running WinXP (yes I know I know ). I'm confused as to what the Jumbo Frame sizes should be set to.

Two of my Gigabyte EP35-D3SR motherboards, uses the Realtek 8111B chip according to Gigabyte's website. I downloaded the latest drivers and the available Jumbo Frame sizes I can set are:

2KB MTU
3KB MTU
4KB MTU
Disabled

So I chose '4KB MTU'.

I have another computer that runs an Asus M4A78-htpc motherboard with an Atheros L1E controller onboard. Again downloaded the latest drivers, but in its Advanced options, it doesn't have a 'Jumbo Frame' option. I do see a 'Maximum Frame Size' option but it appears I can input any number up to 7168. The default is 1514.

So if I've set '4KB MTU' on my other two computers, what should I enter for Maximum Frame Size on the Asus? 4000? I tried searching on google and some sites gave 4088 and others even suggested 4096.

Or does it even matter? Any ideas?

Thanks!

 

[thiggins]

If you are running a current-generation PC, jumbo frames probably won't significantly increase network performance. In the old days of slow internal busses, they could help. But with today's fast processors and PCI-e bus interface, you probably won't see an improvement.

If you're determined to use jumbos, set all your clients to use the same jumbo frame size. Freeform entry is a pain. When I used to test for jumbo frames with NASes, I usually set the value to 4088 if the product required freeform entry vs. a dropdown list.

 

[kk22]

Thanks thiggins for the suggestions!

Do onboard network controllers run off the PCI-e bus or PCI bus? I've always wondered about that. Not that I think the gigabit file transfers will saturate either, is that correct?

 

[teknojnky]

most motherboards in the last 2-3 years are all PCI-E NIC's, older/first generation PCI-E motherboards may have the NIC on the PCI-E or PCI, its all up to the motherboard manufacturer.

for your particular asus, you would have to look at the specs and see if it indicates pci-e network or not.

 

[thiggins]

Do onboard network controllers run off the PCI-e bus or PCI bus? I've always wondered about that. Not that I think the gigabit file transfers will saturate either, is that correct?

As technojnky points out, it depends on the age of the motherboard.

PCI bus interface will limit Gigabit Ethernet speed. PCIe will not.

 

[kk22]

Thanks for the replies technojnky and thiggins! I searched online and it appears the Atheros NIC on the Asus runs off PCI-e.

Always good to learn something new