Retro networking / WAN communities

[Grant Taylor]

On 4/11/22 6:16 PM, Paul Koning wrote:
> I think "hub" is another word for "repeater" (just like "switch" is 
> another word for "bridge").

Interesting.

Do you know of any documentation, preferably not marketing materials, 
that used "repeater" in lieu of "hub"?

 From my naive point of view, hubs came about when multiple stations 
connected to a central location, the center, or hub, of the start if you 
will.  Conversely, I remember reading (after the fact) about repeaters 
as something that existed in pure 10Base5 / 10Base2 networks, predating 
hubs.

I'm questioning form a place of ignorance.  Like a child asking why fire 
is hot.

I think there is a large, > 80%, overlap between switch and bridge, but 
they aren't perfect.  Bridging some traffic between otherwise 
incompatible networks comes to mind; e.g. SNAP between Token Ring and 
Ethernet or Ethernet to xDSL (RFC 1483).

> The device I have is a small standalone box, about the size of today's 
> small 4-6 port switches you buy at Staples for $100.  But it's actually 
> a repeater, not a switch, and one of its ports is a 10Base2 connector 
> (BNC jack).

I would firmly consider what you describe as a "hub".

> AUI connector, yes.  Two are little boxes about the size of the 
> connector body but maybe 2-3 inches long, with the coax or RJ45 
> connector at the other end.  The 10BaseT is a DEC product, the 10Base2 
> I don't remember.  I also have an ancient 10BaseT transceiver that's 
> about twice as big, with a jack for an external power source, forgot 
> the maker of that one.

*nod*nod*  I have had many such things various times in the past.  I 
recently unboxed one that's (from memory) < 2" x < 3" x < 1", with AUI 
on one side and 10Base-T on the other side.

> You won't get an argument from me on that one... :-)

:-D

> That's rather odd because even if someone doesn't obey the letter of 
> the law you'd think they would at least support 100BaseT. Or was the 
> problem lack of half duplex?  Do those management interfaces want to 
> run half duplex?

No.  It's more nefarious than that.  You mentioned supporting n - 1 
generation.  I'm talking about switches that support 1 Gbps / 10 Gbps / 
25 Gbps / 40 Gbps / 50 Gbps / 100 Gbps.  They quite simply don't scale 
down to 100 Mbps much less 10 Mbps.  --  Why would someone want to 
support those slow speed connections on such a high speed switch? 
Devices like intelligent power strips or serial consoles or the likes in 
a cabinet that uses said switch as a Top of Rack device.  --  Our 
reluctant solution has been to put in a lower end / un-manged 10 Mbps / 
100 Mbps / 1 Gbps that can link at 1 Gbps to the main ToR.

> I think I saw in the standard that Gigabit Ethernet in theory includes 
> a half duplex mode, but I have never seen anyone use it and I wonder 
> if it would work if tried.  Perhaps I misread things.

My understanding is that Gigabit Ethernet (and beyond) only supports 
full duplex.  Maybe I'm mis-remembering or thinking about what is 
actually produced vs theoretical / lab experiments.

Similarly, I know someone that has 100 Mbps Token Ring, a.k.a. High 
Speed Token Ring (HSTR) equipment for their mainframe.  And 1 Gigabit 
Token Ring was designed in the lab but never actualized.



-- 
Grant. . . .
unix || die