[HECnet] Maximum number of L2 routers?

[Johnny Billquist]

On 2015-02-28 22:01, Hans Vlems wrote:
That's right, two repeaters between any two stations which gave you 1680 meters spanned    distance. The extra 180 meters come from four transceiver cables, 45 m each.

So, the 200 node limit can't really be right, unless you really are only talking about one cable, and not an ethernet, as a repeater is totally invisible to you, and makes it possible to connect more machines on the ethernet.

The repeater rule btw is lifted by a bridge. And there is a maximum of 7 bridges between stations.

Well, proper bridges are definitely a different thing than a repeater, as a bridge will store and forward.

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.

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.

	Johnny


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Onderwerp: Re: [HECnet] Maximum number of L2 routers?

On 2015-02-28 21:21, Hans Vlems wrote:
Yeah of course you can have more than one L2 router in an area, didn't think of it :)

:-)

About the 10base5 segment, that was limited in length to 500 meters. Transceivers must be at least 2.5 meters apart, hence the 200 nodes. This was before a DELNI was invented. If my failing memory doesn't fail me that 200 node limit remained the same with Delni's.

But you were allowed to bridge several segments (using repeaters). I
think the maximum distance, including hops, between any two nodes had to
be within 1000m, but you could also do stars... You were not allowed to
have more than two repeaters I also seem to remember.

Johnny


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Onderwerp: Re: [HECnet] Maximum number of L2 routers?

On 2015-02-28 20:51, Hans Vlems wrote:
64:-)?

You can definitely have more than one L2 router per area... :-)

I don't know for sure, as you probably    have guessed...
   There is an ncp executor parameter called maximum broadcast routers, default value 32 iirc.
Is there an architectural limit, depends on what you mean by ethernet segment. A 10base5 segment was limited to 200 nodes. 64 L2 routers might put a hefty broadcast load on it. On an extended ethernet LAN there is likely no technical limit.

Really? I have some vague memory of some limit of an ethernet segment,
but I can't recall any details now. Why 200?

Johnny


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Onderwerp: [HECnet] Maximum number of L2 routers?

Hello, list,

I'm trying to remember what is the maximum number of area routers allowed in a DECNET Phase IV ethernet segment. Anyone of you have that information at hand?

On other news, the old macbook I was using as home server has died, after years of service beyond the call of duty. I'm setting up my stuff using several smallish ARM computers. To be specific, now I'm running a cubietruck and and Odroid-C1 (and a raspberry Pi as router/firewall). I'm having trouble with the net connectivity, so some yo-yo disconnects from area 7 should be expected. Not so hard as last sunday, but I'm still doing quite a lot of reboots.

BTW, the SG1 multinet link seems to be down again (unless it is a problem in my side, which is completely possible).







-- 
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