choosing base addresses on NICs

[bhorne.nouce at banet.net (bhorne)]

Jerry,

If it supported full-duplex, it was a switch.  A "hub" is a common channel device,
where every input is echoed to every output - in other words, a resistive bridge
with amplifiers and impedance matching as needed.  A card running full duplex into
a hub would freeze the network.

An Ethernet "switch", OTOH, is actually a router using MAC-layer addressing.  It
has buffers and intelligence adequate to the task of preventing collisions on the
network, which speeds up Ethernet throughput dramatically:  since each station
enjoys it's own buffer space and a separate transmit vs. receive path, they can
leave their transmitters on and thus avoid the performance hit caused by RTS/CTS
delays and packet collisions.

FWIW.

Bill

Jerry Feldman wrote:

> The hub I had in my office at Raytheon supprted full and half duplex
> operation.
> bhorne wrote:
>
> > Not to rain on the parade, but I'll add a couple of caveats for those of us
> > still in the dark ages of Ethernet:  these apply ONLY to twisted pair
> > operation, since coax is always half-duplex.
> >
> > 1. If your NIC is connected to other NICs through an Ethernet ** HUB **, use
> > half-duplex.
> --
> Jerry Feldman <gaf at blu.org>
> Boston Linux and Unix user group
> http://www.blu.org
>
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--
Bill Horne
(Remove ".nouce" from address for direct replies. Sorry.)


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