MII-TOOL(8)          Linux System Administrator's Manual         MII-TOOL(8)

NAME         top

       mii-tool - view, manipulate media-independent interface status

SYNOPSIS         top

       mii-tool [-v, --verbose] [-V, --version] [-R, --reset] [-r,
       --restart] [-w, --watch] [-l, --log] [-A, --advertise=media,...]
       [-F, --force=media] [-p, --phy=addr] interface ...

DESCRIPTION         top

       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.

OPTIONS         top

       -v, --verbose
              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

       -V, --version
              Display program version information.

       -R, --reset
              Reset the MII to its default configuration.

       -r, --restart
              Restart autonegotiation.

       -w, --watch
              Watch interface(s) and report changes in link status.  The MII
              interfaces are polled at one second intervals.

       -l, --log
              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.

DIAGNOSTICS         top

       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.

AUTHORS         top

       David Hinds -
       Donald Becker -
       Bernd Eckenfels -

SEE ALSO         top - Homepage of the net-tools project

COLOPHON         top

       This page is part of the net-tools (networking utilities) project.
       Information about the project can be found at 
       ⟨⟩.  If you have a bug report for
       this manual page, see ⟨⟩.  This page
       was obtained from the project's upstream Git repository
       ⟨git://⟩ on 2019-11-19.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2018-11-03.)  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)