[HECnet] Others DECnets

That sounds vaguely right. I wish I could find all my notes on this. I will keep looking though. -Steve -----Original Message----- From: owner-hecnet at Update.UU.SE [mailto:owner-hecnet at Update.UU.SE] On Behalf Of Paul Koning Sent: Friday, December 04, 2009 09:59 To: hecnet at Update.UU.SE Subject: RE: [HECnet] Others DECnets -----Original Message----- From: owner-hecnet at Update.UU.SE [mailto:owner-hecnet at Update.UU.SE] On Behalf Of Johnny Billquist Sent: Friday, December 04, 2009 6:49 AM To: hecnet at Update.UU.SE Subject: Re: [HECnet] Others DECnets Hi. Steve Davidson wrote: They used to call that poor-mans-routing (PRM), and yes that is basically how it worked. ZKO has over 3000 machines and only had areas 2 and 19. The fix was hidden area support which in this case meant anything from either 63, or 62. I don't remember if they used areas 61 or 60. I managed machines in area 2, 19 and 63. My area 63 nodes were on satellites of clusters (in either area 2 or 19) that has DECnet aliases Worked very well. For those who were unfortunate to not be attached to a cluster PMR was the only way to either send mail, or SET HOST. Yes, PMR is "well known". :-) I think I can see how the hidden network idea can work now. The level one router just needs to have two separate network interfaces, and two separate physical networks, and then it could work. The reason it will work is because DECnet can do a shortcut in some places, one of them being that a level one router can actually talk directly to a level two router in another area. That doesn't sound right. A level 1 router doesn't listen to area route messages so it doesn't know anything about other areas, or area routers. Only area routers do such a thing. I don't remember the actual setup that was used, but I *think* it was like this: The network backbone was built out of area routers that had their max area set to 62 (or whatever was the highest "real" area). Any area that contained hidden-area nodes would connect to the backbone with another area router (or set of them) which have max area set to 63, and all the other nodes in that site would only connect to these max-63 area routers. Those area routers could see the local area 63, but the backbone could not because that's outside the range of area numbers it was supporting. So routing works. Say that node 2.2 wants to talk to 63.123. Assume both are L1 routers for simplicity. 2.2 would send to its nearest area router, which (by the config rule) has max area 63. So it knows how to get to the area 63 router. That path is guaranteed not to involve any backbone routers because those have max area set to 62 so they aren't offering any path to area 63. The packet gets to the area 63 router, which delivers to 63.123. The same works in the other direction. paul