Re: Configuring network after fresh boot to lime2

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

> Are you using the correct cable?  Are you connecting this board to
> another computer or to a router (straight vs crossover cable)?.  This
> device is gigabit.

If it's gigabit, it's auto-X - as I understand it this is required by
the gigabit spec - in which case straight versus crossover doesn't
matter.

> I had problems before with cheap cables,

That _is_ an issue.  I've had such issues myself, and, with the caveat
that this is just my current understanding, here's what's up:

The twisted-pair gigabit spec was stupidly done in one respect: the 1/2
and 3/6 pairs - the two used for 10baseT and 100baseTX - are used to
negotiate capability.  But then, if each end is gigabit-capable (and,
possibly[%], if those two pairs are good enough quality), it then
proceeds to use all four pairs.

Without checking that the other two pairs are good, or even exist.

If you use a cheap cable designed for 10baseT or 100baseTX, it may have
only the 1/2 and 3/6 pairs present.  (This can be obvious upon
inspecting the connector - I've seen cables with pins 4/5 and 7/8
visibly lacking wires.)  This works fine as long as at least one end is
sub-gigabit.  But use such a cable to connect two gigabit devices and
they will, if the two pairs that exist are good enough[%], negotiate
gigabit and, because the other two pairs are missing, fail to actually
transfer data.

The only fixes I know of are to use a gigabit-capable cable or to
administratively restrict at least one end to sub-gigabit speeds.

[%] I'm actually unsure whether it checks medium quality or not.

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