MII-TOOL(8)                          System Manager's Manual                          MII-TOOL(8)



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


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


DESCRIPTION
       This utility checks or sets the status of a network interface's Media  Independent  Inter‐
       face  (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 technol‐
       ogy.  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 inter‐
       face.  If an interface or interfaces are not specified on the command line, then  mii-tool
       will check any available interfaces from eth0 through eth7.

OPTIONS
       -v, --verbose
              Display  more detailed MII status information.  If used twice, also display raw MII
              register contents.

       -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 operation.

       -A media,..., --advertise=media,...
              Enable  and  restart  autonegotiation, and advertise only the specified media tech‐
              nologies.  Multiple technologies should be separated by commas.   Valid  media  are
              100baseT4, 100baseTx-FD, 100baseTx-HD, 10baseT-FD, and 10baseT-HD.


DIAGNOSTICS
       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
       David Hinds - dhinds AT pcmcia.org
       Donald Becker - becker AT scyld.com
       Bernd Eckenfels - ecki AT debian.org



net-tools                              2004/03/28 23:30:00                            MII-TOOL(8)