Date   : Sun, 19 Jul 2009 18:58:04 +0100
From   : pete@... (Pete Turnbull)
Subject: Master Ethernet upgrade

Theo Markettos wrote:
> In article <090719005501@...> you wrote:
>> A hub is effectively the logical equivalent of loads of sockets
>> with all the pin 1s connected, all the pin 2s connected, all the
>> pins 3s connected, etc. A twin econet socket outlet is a two-socket
>> econet hub ;)
> 
> This building is flood-wired with structured cabling, each room having a
> non-token ring of unshielded untwisted pair, with a number of dual-port Layer
> 1 hubs and dropleads to each station.  These are fed from a central Layer 1
> switch to which is attached the WAN connection.
> 
> Ah, it's teatime.  Must go and netboot the kettle.

I'll send you the bill for cleaning the coffee off my screen!

I take it that's a two-pole layer 1 switch?

I didn't initially notice Jonathan's comment about all the pin 1s 
connected etc.  Since one pair is used for transmit and another for 
receive, it couldn't actually work like that :-)  I'm sure Jonathan 
realises this, and just wrote that to illustrate the point, but you'd 
actually connect pin 1 (Tx+) on the first port to pin 3 (Rx+) on every 
other, pin 2 (Tx-) to 6 (Rx-) on every other, pin 3 to all the pin 1s, 6 
to all 2s; then for the next port connect pin 1 to all the 3s, ... hmm, 
looks like we need a few diodes or something there...

-- 
Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York