5000' ethernet?

Michael Powell nightrecon at verizon.net
Thu Jul 16 20:31:51 UTC 2009

David Kelly wrote:

> But it is turned off. A full duplex switch does not echo the sender's
> bits back to the sender's receiver. A full duplex switch buffers the
> incoming bits, reads the header, selects an output port, and then starts
> sending the bits to that one port out of the FIFO. If it is a broadcast
> packet then most cheap switches will wait until all ports are available
> before sending the packet. Perhaps expensive switches will queue a copy
> of the broadcast to each port.
> Last sentences in last paragraph before See Also at
> "Also, in Full Duplex Ethernet, collisions are impossible since data is
> transmitted and received on different wires, and each segment is
> connected directly to a switch. Therefore, CSMA/CD is not used on Full
> Duplex Ethernet networks."

Aha! I did not know this (obviously). Learn something new every day... Maybe 
I'm getting too old for this line of work. The brain just isn't working the 
way it once did. I'm a big proponent of RTFM, but usually am looking at new 
material instead of forgetting stuff I read +20yrs ago. Thanks for setting 
me straight guys, it's better to be "in the know" than the other way around. 
Maybe time to retire.

I remember a Netware 4.12 install where the client had to run twice on full 
duplex because on the first attempt the acks came back too fast. Didn't do 
it on half. Same place I had no end of trouble trying to get a PC we used as 
a controller to connect a check processing transport to the back end 
servers. No matter what I did nothing worked. Turned out they had 600 feet 
of wire and forgotten to put a bridge in the middle that had been initially 


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