[HECnet] Maximum number of L2 routers?/h4000

[Hans Vlems]

   There are three h4000's.
The first had an elaborated tap, which was a pain to install. The second generation used a simple hand drill. We (fuji) used only Dec gear, no problems. The problems for us started when thin wire repeaters were introduced.

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Van: Clement T. Cole
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Onderwerp: Re: [HECnet] Maximum number of L2 routers?

No - this was pre-thinnet. As I recall Cabletron and interlan were selling repeaters as well as DEC. Johnny's right the h4000 was dec's stringer tap transceiver. 3com had a transceiver where you had to cut the cable (or get it pre-made). Mixing manufacturers could be a crapshoot. Repeaters were needed for long segments in larger buildings and thus we sometimes got forced into using them. The number of hours we spent debugging issues I do not want to think about. I was running the data comm group at Masscomp by then and I pretty sure out field service guys tried really hard to tell people to keep the transceivers to a single brand because we saw so many issues in the field. The h4000 I remember being particularly troublesome. 


I have memories of the Masscomp field service guys (who were all ex-DEC) getting a large customer to toss out the h4000 for their Vaxen to solve a number of issues when we trying to make customers talk to our gear. I also recall that The interlan stinger tap was the best of the original stinger taps, although the 3com (cable cut style) worked the best of the early ones and I remember that was the one we recommended for thick-net installations for a long time. A couple of years into it, we did finally find a 3rd party tap that worked really well - but I do not remember the brand. We had a lab with a couple of coils of thick-net in 250 meter segments so we test things. I still have a couple maybe 3 of the strange one we switched too in a box in the basement. Unfortunately, I'm traveling so I can not go downstairs to check the brand. But they were a number years into thick-net so people were finally getting the analog electronics right. 


As for repeaters, I have forgotten which one we tested, but I do remember that that it was one of the dec repeaters worked significantly better than any others; but we generally suggested to not use repeaters but instead multi-home a couple of systems and route as needed. Even with all of routers issues, it worked better than big segments. 

I used to have one old dec repeater in my cache but I'm pretty sure it finally went to the electronics recycler about 3 years ago since I was not using at at home and never going too and my wife was working on getting me to purge excess stuff. I felt it, a couple of old pc's, some Mac-2, and the like that had been powered up in over 10 years had reached there end of life and had no value to anyone more.

Clem

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On Feb 28, 2015, at 7:57 PM, Johnny Billquist <bqt at softjar.se> wrote:

I might be totally confused now, but I have a strong recollection that the H4000 is a tickwire transciever, and if so, I can't make sense of a sentence that talks about it in the context of thinwire ethernet.

Johnny

On 2015-03-01 00:13, Hans Vlems wrote:
That is probably    a story when the first thin wire repeaters were introduced. The h4000-aa wouldn't play nice when connected to a dempr or despr. The h4000-ba fixed that, or you could cut a capacitor (?) on the -aa and save money. A transceiver was 1200 guilders at the time.

Dec's thick wire repeaters (derep-ab and -rd) worked for me. One is still in use today...

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

Right. And many of the repeaters tended to not work well.

DEC had wholes name I forget - that was pretty much the only one that worked reliably. I have bad memories of repeater created issues where host A one seg1 just would not talk to host b on seg2 but c & d could talk to both and each other
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On Feb 28, 2015, at 2:28 PM, Johnny Billquist <bqt at softjar.se> wrote:

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


-- 
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