mouse at Rodents.Montreal.QC.CA
Tue Nov 1 12:13:24 CST 2005
> You missed the Collision wires, and therein lies the trouble.
> There are two issues.
> One is that an AUI based Ethernet was half duplex (just like
It's not entirely fair to contrast AUI and 10base2 this way, as if they
were comparable things. AUI is the interface between the host and the
transceiver; 10base2 is one of various possibilities for the medium on
the other side of the transceiver. Contrasting AUI with 10base2 is a
bit like contrasting RS-232C with POTS phone service (just as the one
applies to different sides of a transceiver, the other applies to
different sides of a modem).
> The other issue is that 8u02.3 compliant NICs will expect the
> collision signal to assert briefly after each packet. That is the
> Collision Test (SQE test, see 802.3 section 184.108.40.206.4).
Some will. Many don't care. I think I have even seen a few that
object if they *do* get that signal. I have some transceivers which
have switchable SQE and have done a little experimenting....
> You said you have lots of transceivers. So why do you want
> crossover? Just hook the AUIs to their coax and wire up a classic
> Ethernet that way.
Perhaps there's no co-ax at ready hand? If the transceivers use
10base5 this seems reasonably likely.
> (For that matter, what's an "AUI Hub"? I know AUI repeaters, and I
> know AUI transceivers.)
In my experience, the term is used colloquially to refer to an AUI
multiport transceiver box, especially one that is capable of running
without a real transceiver attached. (A multiport transceiver is a
device that has multiple - typically 8 - AUI connections suitable for
connecting to hosts and one AUI connection suitable for connecting to a
real transceiver. As far as the hosts are concerned it looks like
multiple transceivers on the same medium. Some of them demand having a
real transceiver on the transceiver port; some have a switch that lets
them run without, and some of the newest auto-sense.)
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