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
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 0x07.
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
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 2021-08-27. (At that
time, the date of the most recent commit that was found in the
repository was 2021-04-22.) If you discover 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 to
net-tools 2013-02-15 MII-TOOL(8)