Gigabit Networking

Q: What's al this about Gigabit networking and how can I get it working?

Now this might get a little technical - apologies for that but please remember that if you don't understand something Google is your friend!!

There is also a simple rule here - cheap kit will not get you to Gigabit speeds, choose good quality switches, routers and cabling and you are on to a good start.

However, the main problem with Gigabit (Gb) networking isn't really the networking bit at all; It's the Hard Drives (HDDs) and the speed at which they can dump the data to the bus.
The PCI bus used can only go to the theoretical limit of 133 MB/s - GB Ethernets maximum transfer rate is 125 MB/s, but you have to remember that most everything is using the PCI bus in the PC. Every card you add in grabs some of the bandwidth which equates to a  slower transfer speed.

A PCIe bus allocates 250MB/s to each channel this is why its seriously faster.

To test transfer rates you can always try transferring large files from a RAM disk to a RAM disk - this eliminates the fragmentation and HDD problems, and should give a truer representation of the speeds.

Here's a few tips if you are experiencing problems:

• Make sure ALL the NICs (Network Interface Cards) are PCIe - I have yet to get a good Gb network speed on PCI NICs for the reason above.
• Set the NICs to 1000/full in the NIC configuration under device manager
• Disable any QOS you have going on
• Make sure you have fast HDDs and are getting good throughput on them (5400 ain't too good for this, best with SSDs)
• Disable Checksum Offloading again in the NIC configuration under device manager
• Disable any 'Green' or 'Eco' networking
• Try changing the settings for - Jumbo Frames and flow control
• Try disabling 'Auto tuning' using - start >> run >> cmd >> netsh interface tcp set global autotuninglevel=disabled
• Defrag your drives
• Make sure your drives are not compressed (right click drive >> properties)
• If Windows 7 - try disabling the 'Link-layer Topology Discovery Mapper I/O Driver'
• Check your cables runs are as short as they can be and are away from power cables.
• Try disabling SMB:
  • start >> run >> cmd >> 
    sc config lanmanworkstation depend= bowser/mrxsmb10/nsi
    sc config mrxsmb20 start= disabled
    (change disabled to auto to reenable SMB)
• Open the registry to 'HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\lanmanworkstaion'.
  • Check DWORDs 'MaxCmds','MaxThreads' and 'MaxCollectionCount' under this branch.
  • Assign them a value of MaxCmds = 30, MaxThreads = 30 and MaxCollectionCount = 32 - make them if they are not there. 
  • After you restart your system, you should see an increase in the performance.

Don't forget that your drives will have a real speed difference for read/write performance. Slow read or write on one drive will effect performance.
Also - try RoboCopy - it uses some of the changed API of the SMB copy.
If you are getting a transfer speed of about 20-80 mb/s you are doing quite well!