Retro networking / WAN communities

[Grant Taylor]

On 4/12/22 11:41 AM, Paul Koning via cctalk wrote:
> I don't know anything about the 3 Mb/s prototype other than that 
> it existed.  When I speak of Ethernet and its "day 1" I mean 10 Mb/s 
> Ethernet as defined by the DEC/Intel/Xerox spec.

Okay.  Fair enough.

I surmise that we're talking about Ethernet II a.k.a. the Digital / 
Intel / Xerox that was commercialized.

> Repeaters are a core part of that spec, and they were among the first 
> wave of products delivered by DEC.

I can see how the need for repeaters was learned during Ethernet 
research at Xerox PARC and incorporated into Ethernet II / DIX from the 
start.

> I no longer remember.  That's possible, or perhaps they were a number 
> of small segments each with a handful of stations on them.

That would make /some/ sense.  E.g. have a 10Base2 segment for a set of 
cubicles and then link the multiple segments together with a multi-port 
bridge.

> That's true but only part of the story.  For one thing, as I said, 
> both mechanisms were part of bridges from the start (at least from 
> the start of DEC's bridges, which may not be quite the very earliest 
> ever but certainly are the earliest significant ones).

Fair enough.

> The learning part of bridging is actually the hard part.  ...

I feel like the conceptual algorithm / logic is simple.  I concede that 
implementing it within timing requirements could be non-trivial ~> 
difficult.

> Spanning tree is indeed another algorithm / protocol, but it's a 
> control plane algorithm with relatively easy time constraints, so 
> it's just SMOP.

I guess I always assumed that spanning tree came along /after/ and / or 
/independently/ of bridging / switching.

After all, the BPDU in spanning tree is "Bridge ..." so that name tends 
to imply to me that it came about /after/ bridges were a thing on at 
least some level.

> That rings a bell.  Someone reminded me of 100Base-T4.

T4 rings a bell for me.  --  It reminds me of some references to T2 and 
T8.  It seems as if there was great conflation between the number being 
reference to wires; 4 vs 8, and pairs; 2 vs 4, respectively.

> In any case, there were two proposed, one that made it.  The other 
> might have gone as far as one or two shipping products, but no further 
> than that.

Yep.



-- 
Grant. . . .
unix || die