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.
Display more detailed MII status information. If used twice,
also display raw MII register contents.
Alert: If used three times, will force reading all MII
registers, including non standard ones. It's not guaranteed
any valid answer from PHY while PHY communication can even
hang. With driver e1000e will fail while reading register
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
-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.
-p addr, --phy=addr
Override the MII address provided by kernel with value addr.
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
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.
This page is part of the net-tools (networking utilities) project.
Information about the project can be found at
⟨http://net-tools.sourceforge.net/⟩. If you have a bug report for
this manual page, see ⟨http://net-tools.sourceforge.net/⟩. This page
was obtained from the project's upstream Git repository
⟨git://git.code.sf.net/p/net-tools/code⟩ on 2017-03-13. If you dis‐
cover any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page, or
you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
net-tools 2013-02-15 MII-TOOL(8)