This utility checks or sets the status of a network interface's Media
Independent Interface (MII) unit. Most fast ethernet adapters use an
MII to autonegotiate link speed and duplex setting.
Most intelligent network devices use an autonegotiation protocol to
communicate what media technologies they support, and then select the
fastest mutually supported media technology. The -A or
--advertise options can be used to tell the MII to only
advertise a subset of its capabilities. Some passive devices, such as
single-speed hubs, are unable to autonegotiate. To handle such
devices, the MII protocol also allows for establishing a link by
simply detecting either a 10baseT or 100baseT link beat. The -F
or --force options can be used to force the MII to operate in
one mode, instead of autonegotiating. The -A and -F
options are mutually exclusive.
The default short output reports the negotiated link speed and link
status for each interface. If an interface or interfaces are not
specified on the command line, then mii-tool will check any
available interfaces from eth0 through eth7.
Display more detailed MII status information. If used twice, also
display raw MII register contents.
Display program version information.
Reset the MII to its default configuration.
Watch interface(s) and report changes in link status. The MII
interfaces are polled at one second intervals.
Used with -w, records link status changes in the system log
instead of printing on standard output.
-F media, --force=media
Disable autonegotiation, and force the MII to either 100baseTx-FD,
100baseTx-HD, 10baseT-FD, or 10baseT-HD operation.
-A media,..., --advertise=media,...
Enable and restart autonegotiation, and advertise only the specified
media technologies. Multiple technologies should be separated by
commas. Valid media are 100baseT4, 100baseTx-FD,
100baseTx-HD, 10baseT-FD, and 10baseT-HD.
SIOCGMIIPHY on 'eth?' failed: Invalid argument
If the interface is not running (up), kernel will refuse to report its link state.
SIOCGMIIPHY on 'eth?' failed: Operation not permitted
Most kernels restrict access to root.
SIOCGMIIPHY on 'eth?' failed: No such device
This error is shown, if the kernel does not know about the named device.
SIOCGMIIPHY on 'eth?' failed: Operation not supported
The interface in question does not support MII queries. Most likely, it does not have
MII transceivers, at all.