[HECnet] Re: How Poor is your Man's Routing?

On Nov 27, 2022, at 6:25 PM, Thomas DeBellis <tommytimesharing(a)gmail.com> wrote: Tops-20 NFT, FAL and NRT will do something called Poor Man's Routing (or PMR, for short). The Tops-10 NRT client will also do it. PMR is something I dimly recall from Phase II or III; this was back before 36 bit hosts could do full routing. Here is some background: On CCnet, we had enough 20's that not all could be connected to each other in a star network. Not even Columbia had enough KMC's to 'star' our 20's; the closest we got was a ring. CMU had even more. When a 20 wasn't next door to whatever system you wanted to get to, you had SET HOST to one that did and then do another SET HOST accordingly. Or maybe you had to do that a few times. The manual procedure and all the accounts involved was clunky enough that pretty much only systems staff did this. It was out of the question for researchers and paying customers. So I think some site on CCnet came up with the idea of automating it to a certain extent. It was called "Poor Man's Routing" and the way it worked is that you specified the route to the system in question. Let's say you were on NODEA:: and wanted to go to NODEC:: yet did not have direct connectivity. If both NODEA:: and NODEC:: had connectivity to NODEB::, then the relevant part of the configuration looked something like this: NODEA:: ↔ NODEB:: ↔ NODEC:: If NODEB:: was a PMR host, then you could do something like SET HOST NODEB::NODEC:: and the parser would convert this to some intermediate string. Instead of opening a connection on DECnet object 23, it would use object 123 and NODEB:: was responsible for taking the rest of the string and getting you to the right place. It worked well enough if the systems in question weren't excessively loaded (which was invariably never the case) and it saved us when the dates for version 6 slipped. I had been under the impression that some site on CCnet had done this and remember eagerly flushing all of it when we finished the field test. Much to my surprise an acquaintance of mine at Marlboro (Larry Campbell) formalized this with a separate module called DNCONN.MAC. I put this into a conditional assembly in part to save some address space (only to get blown out of the water by some vestigial code that had never been hit). Does anybody remember PMR? Did it exist for the other systems which supported DECnet? Just curious whether I should turn this on for anyone.