On Mar 2, 2015, at 10:27 AM, <Paul_Koning at Dell.com> <Paul_Koning at Dell.com> wrote:
On Mar 1, 2015, at 5:50 PM, Hans Vlems <hvlems at zonnet.nl> wrote:
Paul, so if more decnet routers are heard of on the land, what happens with:
A) the list that gets transmitted is truncated, the 32 most recent routers and the transmitting host itself are on it?
B) the locally maintained list, is that also limited to 33 entries?
Almost (A) but not quite. If more than the max routers show up on the Ethernet (whatever that limit is it can be set to less than 33), the excess are dropped first based on router priority, and if it s a tie then by address (higher address wins). See section 9.1.1 in the DNA Routing spec. The adjacency that s rejected as a result is logged event 4.16, with no reason code because the Netman spec forgot to define a specific reason code for this particular case.
And yes, the locally maintained list is also limited. That s critical; distributed routing protocols require that all routers agree on the routing data (after transient differences due to changes propagating have settled out). Otherwise you end up with persistent loops. So the information that s transmitted to other routers and the information used for local computation must be the same.
An analogous issue appears in link state routing (Phase V and other link state protocols derived from it, like OSPF). There, it is necessary for all routers to store the same link state the same map of the area. If some don t have enough memory to do that, some serious magic is required to ensure they are handled specially, since they can t calculate correct routes if they can t store all the inputs. This is why Phase V has special rules for overloaded routers. I remember when that issue was first raised, and the brainstorming that resulted in an attempt to arrive at a solution. The current one is due to Mike Shand, as I recall, and is incredibly simple; before that one, some much more complicated approaches were concocted by other members of the team.
paul
On Mar 1, 2015, at 5:50 PM, Hans Vlems <hvlems at zonnet.nl> wrote:
Paul, so if more decnet routers are heard of on the land, what happens with:
A) the list that gets transmitted is truncated, the 32 most recent routers and the transmitting host itself are on it?
B) the locally maintained list, is that also limited to 33 entries?
Almost (A) but not quite. If more than the max routers show up on the Ethernet (whatever that limit is it can be set to less than 33), the excess are dropped first based on router priority, and if it s a tie then by address (higher address wins). See section 9.1.1 in the DNA Routing spec. The adjacency that s rejected as a result is logged event 4.16, with no reason code because the Netman spec forgot to define a specific reason code for this particular case.
paul
El 01/03/15 a les 23:35, Paul_Koning at Dell.com ha escrit:
Interestingly enough, the DECnet network management architecture spec says the limit is 255. 33 is correct, actually; the reason is that an Ethernet router hello message contains a list of the other routers heard by this router, and the encoding of the packet limits the length of that list to 33 entries. paul
I was afraid the users of Johnny's bridge could be over that limit, since all the connected networks are -from DECNET point of view- part of the same ethernet (all the nodes are adjacent). I have taken a look at the HELLO messages I'm getting and I see just 10 routers, so we are still far away from the absolute limit, but just at the recommended maximum.
Paul, so if more decnet routers are heard of on the land, what happens with:
A) the list that gets transmitted is truncated, the 32 most recent routers and the transmitting host itself are on it?
B) the locally maintained list, is that also limited to 33 entries?
Hans
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Onderwerp: Re: [HECnet] Maximum number of L2 routers?
On Feb 28, 2015, at 3:00 PM, Jordi Guillaumes i Pons <jg at jordi.guillaumes.name> wrote:
...
Use the SET CIRCUIT command with the MAXIMUM ROUTERS parameter to set the maximum number of routers permitted on a particular Ethernet or FDDI circuit. The largest number of routers allowed on a LAN is 33, which is the default value of the MAXIMUM ROUTERS parameter.
Interestingly enough, the DECnet network management architecture spec says the limit is 255. 33 is correct, actually; the reason is that an Ethernet router hello message contains a list of the other routers heard by this router, and the encoding of the packet limits the length of that list to 33 entries.
paul
On Feb 28, 2015, at 3:00 PM, Jordi Guillaumes i Pons <jg at jordi.guillaumes.name> wrote:
...
Use the SET CIRCUIT command with the MAXIMUM ROUTERS parameter to set the maximum number of routers permitted on a particular Ethernet or FDDI circuit. The largest number of routers allowed on a LAN is 33, which is the default value of the MAXIMUM ROUTERS parameter.
Interestingly enough, the DECnet network management architecture spec says the limit is 255. 33 is correct, actually; the reason is that an Ethernet router hello message contains a list of the other routers heard by this router, and the encoding of the packet limits the length of that list to 33 entries.
paul
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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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
Sent from my iPad
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
Sent from my iPad
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
Thin wire repeaters had an AUI port too. That way they could connect to existing backbones. With h4000's
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Onderwerp: Re: [HECnet] Maximum number of L2 routers?
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
Sent from my iPad
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
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
Sent from my iPad
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
Sent from my iPad
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
Right
Sent from my iPad
On Feb 28, 2015, at 7:54 PM, Johnny Billquist <bqt at softjar.se> wrote:
On 2015-02-28 23:13, Clement T. Cole wrote:
I should have added when Stan and I wrote the original IP/TCP for VMS @ Tektronix did not have routing in it (nor mail support). We gave to CMU who enhanced it and I assume added routing. DEC did not support an IP stack until much later - Johnny probably remembers when it became available. I had stopped having to hacking on VMS when I left Tektronix in '81.
I don't know, actually.
However, it should be pointed out that routing is not the same as bridging...
Johnny
Sent from my iPad
On Feb 28, 2015, at 3:24 PM, Cory Smelosky <b4 at gewt.net> 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)
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?
Johnny
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|| on a psychedelic trip
email: bqt at softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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
Sent from my iPad
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
