Correction:   someone wrote:
>
>10BaseT and 100BaseT cable has to be "straight-through", unless you're
using a >crossover cable between two nodes, in which case two pairs get
swapped.
>
----------------------------------------
This correct but may lead you to wire it up wrong. Read the following so you
won't waste RJ45 connectors.

10BaseT and 100BaseTX are wired in a non-obvious pairing, with the first
pair using pins 1 and 2, but the second pair uses pins 3 and 6.  The other
two pairs (pins 4,5) and pins 7,8 are usually present, but do not carry
signals in 10BaseT and 100BaseTX.  They are usually used only in an
emergency as spares if the primary pairs are cut and the cable is
inacessable for replacement.

It is correct to say that the cable is "straight through", since each pin
at one end is connected to its same pin number at the other end.  But do
not put the first pair on 1&2, second pair on 3&4, third pair on 5&6,
fourth pair on 7&8.  If you go any distance with this pairing it won't work
or you get lots of errors.  Hubs and network interface cards send and
receive using the pin 1&2, pin 3&6 pairing, respectively.  The colors shown
below are widely used, but arbitrary as long as the pairing is respected.

     RJ45 Plug PIN#             RJ45 Plug PIN#
 1st PAIR  /--  1   Orange/White           1 TxData +
           \--  2   Orange                 2 TXData -
           /--  3   Green/White            3 RxData +
 2nd PAIR /     4 -\ 3rd PAIR /Blue/White  4
          \     5 -/          \Blue        5
           \--  6   Green                  6 RXData -
                7 -\ 4th PAIR /Brown/White 7
                8 -/          \Brown       8
  Plug
  (Looking at connector
   end with the cable
   running away from you)

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Regards,
  Ron Fial