Ethernet Ports

[David Bandel]

On 5/8/06, Matthew Carpenter <matt at eisgr.com> wrote:
> On Saturday 06 May 2006 04:07, James McDonald wrote:
> > Or just unplug the cables and then look at the output of ethtool ethX
> > and check for the Link Detected Yes/No status.
> Just a side note on this.
>
> Typically, ifconfig shows the "RUNNING" flag for nics with link.
> I haven't found this documented so it may not always be the case, but
> empirically, it works.

The better way to see this is to use iproute2's ip command:
ip li sh (ip link show).  This will show you if you have a carrier
signal present or not which should equate to the ambiguous RUNNING
used by ifconfig.

>
> David, would you like to comment on this?  Perhaps you can speak for the
> validity of this?

I prefer to use more definitive tools, like mii-tool for mii cards,
but ip works for all cards so is often a better choice.  While you can
plug a light bulb into a socket to see if it has power, a multimeter
will tell you so much more (like if you have the correct voltage or a
low or high voltage condition).  OTOH, I guess that means you also
need to know what range constitutes "good" voltage (or what FD and HD
mean to your transmissions).

Ciao,

David A. Bandel
--
Focus on the dream, not the competition.
            - Nemesis Air Racing Team motto