[HECnet] PSTHRU.EXE poor-man routing object 123 for VMS on VAX -->Tops10

[R. Voorhorst]

The PMR/PSTHRU is on the Trailing Edge Pdp10 archive: TOPS-10 Tools
BB-FP64B-SB in Saveset TOPS10 Unsupported Tools in directory:
  163   103770(7)  <455> 10,773    6-Jul-87 dskb:[10,7,psthru]psthru.mac
   36    22550(7)  <455> 10,773   12-Jul-83 dskb:[10,7,psthru]psthru.plm
   40     5120(36) <455> 10,773    1-Sep-88 dskb:[10,7,psthru]psthru.exe
   39    24570(7)  <455> 10,773   24-Feb-84 dskb:[10,7,psthru]pmr.mac

Reindert


-----Original Message-----
From: owner-hecnet at Update.UU.SE [mailto:owner-hecnet at Update.UU.SE] On Behalf
Of Paul Koning
Sent: Monday, 27 December, 2021 19:42
To: hecnet at update.uu.se
Subject: Re: [HECnet] PSTHRU.EXE poor-man routing object 123 for VMS on VAX



> On Dec 26, 2021, at 6:04 PM, Thomas DeBellis <tommytimesharing at gmail.com>
wrote:
> 
> ...
> Could you elaborate on what 'poor man' routing means, just so I'm sure I
have the correct context?  I know that this term existed for 20's route NRT
sessions.  It doesn't exist for CTERM.  I don't think I remember seeing it
for DAP/FAL/NFT.

"Poor man's routing" as it appears in DECnet means a way to communicate with
nodes that are unreachable by the primary protocol mechanisms.  It works by
making the user specify an explicit path to the destination (shades of uucp
mail).  For example, mail might be addressed to  VAX4::STAR::Goldstein,
i.e., the recipient was on node STAR but to get there I'd have to use VAX4
as an intermediate point.

In Phase II, PMR would be used to reach destinations more than one hop away.
With a mix of Phase III and IV, the Phase III nodes would need PMR to reach
out of area destinations.  And when "hidden areas" were used to deal with
topologies that needed more than 63 areas -- such as DEC's internal network
-- PMR would be used to get into or out of a hidden area.

PMR the concept might be implemented in a number of different ways.  Some
applications, like MAIL, would provide it as part of the application.  File
transfer (DAP protocol) would offer it as a side effect of VMS transparent
network access.  And some applications, I think the old network terminal
protocols might be an example, would rely on a separate application layer
forwarder program.  That would be PMR or PSTHRU, object 123.

PMR as a separate program might originate on TOPS-10 since it has a program
by that name that also provides the equivalent service on ANF-10.  Someone
posted the source of that recently (a year ago or so, perhaps).  I don't
remember ever seeing a protocol spec for the PMR protocol.  Since I have the
RSTS source code (it's a program PMR.BAS, in Basic-PLUS) I can reverse
engineer such a spec, that's on my "soon" list.  I don't remember if PMR was
included with the DECnet kit.  It's a pretty small and simple program.

	paul