Ghosting with Linux

[Gerald Combs]

On Thu, 21 Aug 2003, Jason Clinton wrote:

> Dustin Decker wrote:
> 
> You running at full duplex?
> D.
>   
> 
> IIRC, 100 Mb is not possible at half duplex thus the switch would not
> indicate a 100 Mb link.

Sure it is.  In fact, if you're plugged into a 100 Mbps hub you don't have
a choice - you're stuck with half.

Under Linux you can use mii-tool to set duplex:

    -F media, --force=media
        Disable autonegotiation, and force the MII to either 100baseTx-
        FD, 100baseTx-HD, 10baseT-FD, or 10baseT-HD operation.

You can also use it to verify that each box has the same duplex settings.
Duplex mismatches can (and often do) result in horrible performance.

GigE may force full duplex.  I can't remember off the top of my head.