[HECnet] Maximum number of L2 routers?

[Johnny Billquist]

On 2015-02-28 22:24, Cory Smelosky wrote:
On Sat, 28 Feb 2015, Johnny Billquist wrote:

Not sure what you mean with a star configuration. The first
(proprietary) glass fiber repeaters were star designs, was that what
you meant?

Not all ethernet segments have to be in one line. But since the
maximum number of repeaters between any two nodes were two, you could
(obviously) have repeaters in configurations that just made sure not
more than two were involved in any given path, but there could be more
than two totally.
The simplest such configuration would be a star.


How are you doing more than one line without bridges or repeaters? Have
I misread?

(Not counting routing)

I was referring to repeaters. They are totally invisible to the ethernet, so I do not consider to cables connected by a repeater to be two different ethernet segments.

But if others do consider that separate segments, then we atleast understand each other. :-)

But the reality of it is that on your ethernet connection, you can see more than 199 other machines, even without switches or bridges.
The 500m limit of the ethernet cable is just because of signal quality. The design as such put an upper limit on how far apart two hosts can be, in time, for the collision detection to work properly. The is a hard limit.
The 2.5 meter between transcievers is also more of an effect of physics. :-)

But my memory is fuzzy enough at this point that I should probably go
read the docs instead of continuing to ramble here...

DEC also sold remote bridges and repeaters. A glass fiber trunc
connected either two remote repeaters or bridges or one of each. I
forgot how long a fiber segment could be, 2500 m IIRC. That gave you
some room to plan on a large site. Two remote repeaters counted as
one in the two repeater rule.
Expensive stuff though. A Lanbridge 100 was 30.000 guilders in 1988.
A remote bridge was even more expensive.

Yeah.

But the ethernet was older than those devices. If my memory serves me
right, the original repeater (from DEC) was the DEREP. Probably even
more expensive back in the day. :-) And there were no bridges back then.


Hmmmm, when did VMS/BSD get software bridging capabilities?

No idea. Can VMS do bridging now?

	Johnny


      Johnny




-- 
Johnny Billquist                                   || "I'm on a bus
                                                                  ||   on a psychedelic trip
email: bqt at softjar.se                         ||   Reading murder books
pdp is alive!                                         ||   tryin' to stay hip" - B. Idol