>> 10base2 : BNC  /=  10baseT : UTP

True...as far as it goes.

> Well, frankly I don't understand why /.* after 10base[25T] is
> necessary at all.  AFAIK, 10base2 means you use BNC connector and
> coaxial cable,

Right.

> 10base5 means you use AUI, tranceiver and the yellow cable (forgot
> the official name),

(I've seen "yellow cable" that was colored orange, btw.)  Right, since
nobody ever did 10base5 without separate transceivers.

> and 10baseT means you use RJ45 and UTP cable.

Right (modulo pickiness about "RJ45"; see below).

> So, to me, it seems totally redundant.

> Why can't we just use 10base[25T]?

Because if you're using the AUI connector, there's no way to tell
whether you're using 10base5, 10base2, or 10baseT.  All AUI is is a
well-defined transceiver interface.  10base* is on the other side of
the transceiver from anything the host can detect or control through an
AUI interface.  I've used AUI with all three media types, at various
times.  There's no conceptual reason one couldn't build a host
interface that connected directly to 10base5 cable, but AFAIK nobody
ever did; whenever 10base5 was used, the host interface was AUI.

This then makes it sound as though it should take just a connector
name: "AUI", "BNC", or "RJ45ish"[%].  But while BNC implies 10base2,
RJ45ish just implies twisted pair; you could want 10baseT or 100baseTX
or possibly even others (eg, CDDI), and some interfaces have to know
what you want.  This is presumably why the 10base* part is there in the
string.

Yes, this is a mess.  I suspect there simply is no set of media strings
that is both accurate and reasonably intuititive.  Personally, I'd
prefer to see "AUI", "BNC", "UTP/10baseT", "UTP/100baseTX", etc.

[%] As I understand the RJ names, RJ45 refers to an eight-conductor
    jack wired up for telephony in a particular way.  10baseT and
    100baseTX are not telephonic at all, so they aren't RJ45 - they
    just use a physically compatible jack.

					der Mouse

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