[ILUG] Re: Network cable questions

[Johno Sullivan]

On Fri, 14 Jan 2000, Jeremy Smyth wrote:

>If you've got two RJ45s, a length of cat5, and a crimper you could do the
>following ...
>
>Find a diagram of an RJ45, find pin 1, and then at the far end of the cable,
>make sure this happens:
>
>1 - 6
>2 - 3
>3 - 2
>4 - 4
>5 - 5
>6 - 1
>7 - 7
>8 - 8
>
>Lines 1 and 6 , and 2 and 3 are crossed over, hence the name.
>
>Now all you need to do is get the bits... 
>
>/jer
>(sick of making the bloody things)

this won't work for 100mb cards. it probably works for 10mb cards though.
also if you're making long cables its important to use the pairs of wires
for pins 1-2, 3-6, 4-5 and 7-8 otherwise you don't get the benefits of 
twisted pair. its a good idea to do this with short cables too. oops, just
had a second look, the layout above is wrong anyway. 10mb crossover should
look like this
1 - 3
2 - 6
3 - 1
6 - 2

from http://www.faqs.org/faqs/LANs/cabling-faq/index.html

    12.2 Ethernet 10Base-T Crossover patch cord;
    This cable can be used to cascade hubs, or for connecting
    two Ethernet stations back-to-back without a hub (ideal for
    two station Doom!)  Note pin numbering in item 10.0 above.

     RJ45 Plug  1 Tx+ -------------- Rx+ 3  RJ45 Plug
         2 Tx- -------------- Rx- 6
         3 Rx+ -------------- Tx+ 1
         6 Rx- -------------- Tx- 2